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383 articles found

AN709-Determination of Loss on drying by TGA according to ASTM E1868 Private content

A loss-on-drying test is designed to determine the amount of any kind of volatile matter in a sample when the sample is dried under specified conditions. Here, the loss-on-drying of a lubricant (cutting oil) was determined using the LABSYS evo TGA 1150, according to the procedure described in the ASTM E1868-10 standard. This test method applies to a wide variety of solid or liquid materials, mixtures or blends when the major component is stable at the test temperature.

AN698 – Gas hydrate nucleation in water-in-oil emulsions Private content

Gas hydrates, also known as clathrates, are crystalline compounds made of gaseous molecules trapped in water cages. Most low molecular weight gases, such as methane, carbon dioxide or nitrogen can form hydrates at suitable low temperatures and high pressures. These solids can naturally be found in the deep ocean floor, in lake and ocean sediments but also undesirably in pipelines. In the latter case, hydrate crystals might agglomerate and cause flow assurance issues such as reduced flow, plugged line or equipment damage. To have a better understanding of the underlying conditions leading to their formation, differential scanning calorimetry, operated under high pressure, is a very useful technique to study thermodynamic and kinetic properties such as nucleation.

AN697 – Effects of pressure on the Wax Appearance Temperature (WAT) of crude oils Private content

In the petroleum industry, waxes crystallization resulting from the precipitation of paraffins contained in oils, can occur in reservoirs, pipelines and process equipment. Many major issues can be related to these deposits, including a modification of the flow characteristics, a reduced production or even a blocked line in the worst cases. To evaluate the possible wax precipitation of a given fluid, the wax appearance temperature has to be determined. It is defined as the temperature at which a crude oil first precipitates. Most of the studies about WAT are carried out under atmospheric pressure. However, WAT determination under experimental conditions close to real operating ones (particularly under pressure) is a key point to predict the crude oils behavior.

AN696 – Wax Appearance Temperature (WAT) determination of crude oils usingthe DSC technique

The wax appearance temperature (WAT), also known as the cloud point, is an important characteristic to evaluate the possible wax precipitation of a given fluid. It is defined as the temperature at which a crude oil first precipitates. In the petroleum industry, such wax depositions in pipelines and reservoirs can lead to many issues,
including a reduced flow or even a blocked pipeline, with subsequent important production problems. Different techniques have been developed to measure the WAT of a crude oil but the method using DSC is commonly used for its rapidity, convenience and accuracy.

AN695 – Hydrogen sorption studied by manometric (Sievert’s) techniques alone and coupled to calorimetry

With the recent advances in solid state research and the development of new synthesis paths, only small amounts of material are produced. To investigate the sorption properties of these small samples an accurate tool for measurement is required. The microdoser attachment of PCTPro can measure sample quantities down to mg’s.
The management of the heat released during the formation of a chemical hydride is critical for practical applications. This is particularly true when poorly stable chemical hydrides are involved. It is highly desirable to be able to quantify and validate reaction enthalpies in situ during a sorption measurement.
Metal-organic frameworks (MOFs) are interesting porous materials because their properties can be tailored for specific applications. Today these structures are envisaged for multiple applications in gas adsorption, like hydrogen storage, selective adsorption of CO2 against CH4, or CO2 against H2. The MOF-5 (fig 2.) is chosen as an example of a commercially available Metal Organic Framework to demonstrate the capacities of coupled Sievert’s technique and heat flow calorimetry at very low temperature.

AN694 – Characterization of proteins Private content

Research and development is of vital importance in the pharmaceutical industry. To obtain a perfectly characterized controlled and stabilized protein based drug, the researchers use different techniques among which differential scanning calorimetry holds an important place. Indeed when heated, a protein undergoes unfolding or denaturation, which is characterized by and endothermic effect on a DSC trace. Once unfolded, proteins can also go through an aggregation process which is typically exothermic.
SETARAM Instrumentation developed ?SC a new microcalorimeter with the following characteristics:
– Dual samples capacity
– Removable and cleanable cells that allow avoiding troubles linked with gel formation or aggregates deposition
– Improved limit of detection
– An extended temperature range from -40°C up to 200°C
Examples of application in the field of proteins characterization are detailed in the present document.

AN693 – Thermal analysis, calorimetry and molten salt Private content

A salt which is solid under standard temperature and pressure conditions and liquid at elevated temperatures can be designated as a molten salt. There is a growing interest for molten salts in different fields, including thermal energy storage, heat transfer, catalysis or chemistry. While for the two first cases, their interesting thermodynamic properties (heat capacity and thermal conductivity) are applied, in the two other cases they are used for their ability to dissolve substances (especially oxides, carbides, nitrides and metals). High temperature calorimetry can bring key information on the thermal properties of pure or blends of salts, like melting / crystallization temperatures, heat of melting, heat capacity and heat of mixing and / or dissolution.

AN692 – Thermal analysis and volumetry solutions for the evaluation of gas sorption and porous properties Private content

Shale gas, coming from organic matter trapped in shale, is a major growing unconventional gas
resource. But there is a need for a more into depth understanding of phenomena linked with its
formation, with the determination of the amounts in place in a reservoir, and on its processes of
recovery. For instance: reliable sorption isotherms at high-pressure and high temperature conditions
which are conditions met in the shale geological formations.

AN691 – Thermogravimetry and calorimetry applied to the study of cement hydration Private content

The Romans built enduring structures from hydraulic cements 2000 years ago, but the way anhydrous starting materials convert into hydrates remains a mystery. Its understanding, and control remains a challenge especially in modern cement or concrete applications such as large constructions or oilwell industry where cement hydration conditions are particularly tough.

AN690 – GRAPHENE: A new field of applications for thermal analysis techniques Private content

Graphene is a two dimensional material consisting of a single layer of carbon atoms arranged in a honeycomb or chicken wire structure. It is the thinnest material known and yet is also one of the strongest. It conducts electricity as efficiently as copper and outperforms all other materials as a conductor of heat. Graphene is almost completely transparent, yet so dense that even the smallest atom helium cannot pass through it. All these new developments require a good knowledge of the physical and chemical properties of grapheme and the corresponding composites. As in many other new fields, thermal analysis offers a large range of methods to fulfil the experimental needs.
Some examples are given to illustrate the works that are done with Setaram thermoanalyzers.

AN686 – Oxidation Induction Time (OIT) of lubricating oil using the TG-DSC technique Private content

The Oxidation Induction Time (OIT) method is very widely used for testing the oxidative stability of polymeric materials but also organic materials such as oils, greases, lubricants… DSC is the standard technique used for such determination that is covered by different standards especially ISO11357-6. In this case , OIT is defined as the time to the onset of the exothermic oxidation peak for a sample exposed to air or oxygen at an elevated oxidation temperature. But it is less common to use the simultaneous TG-DSC technique for such a determination. This technique is applied on a lubricating oil.

AN685 – Melting of NaCl and NaF using the TG-DSC technique Private content

The thermal properties of halides are characterized by melting and dehydration of water present at a particular stage during heating. Halite is the mineral form of NaCl and Villaumite is the mineral form of NaF. The two characteristic halides are investigated using the TG-DSC technique in order to investigate their stability

AN684 – Unfolding and aggregation effects of Beta-lactoglobulin using MicroSC

Globular proteins are widely used in food and pharmaceutical industries because their unique folded structure leads to interesting active principle or flavor binding, water solubility, or gelation properties. The thermally induced structural modifications of a protein do not only depend of its origin and extraction, purification conditions, but also of its environmental conditions like pH, salt content, or solvent type. β-Lactoglobulin (β-LG) is the major whey protein of cow and sheep’s milk. β-LG is a well-characterized globular whey protein which exists mainly in its dimeric form between pH 3 and 7.

AN683 – Starch retrogradation and bread staling Private content

Gelatinized starch goes through retrogradation, which involves recrystallization of amylose and amylopectin. Retrogradation characteristics depend on parameters like botanic specie or water content. It is the main source of bread staling effect. Ageing of maize, wheat starch dough and of bread crumb, was studied with the state of the art µSC microcalorimeter.

AN679 – Temperature cycling stability of Phase Change Materials

Some materials have the capacity to store and release large amounts of energy by changing their
physical sate: they are called Phase Change Materials (PCM). They can be used for instance to minimize
the need of air conditioning and heating: incorporated into walls of buildings, they absorb heat when
outside temperature is high, and release it when temperature decreases. This keeps the house into a
“comfort temperature zone”. Another utilization of the PCM is the use of residual heat from exothermic
reaction in industry as a source of energy. An application fitting phase change temperature and a large
melting enthalpy are two obvious requirements for these materials. However, there is another
important parameter: the cycling stability, in order to use the PCM as many times for storage and
release of heat as required by an application

AN678 – Pyrolysis study of lignocellulosic biomass and its components by DSC Private content

Wood, straw, sugarcane bagasse and coconut shell are examples of lignocellulosic biomass. This category of biomass is mainly composed of cellulose, hemicelluloses and lignin. Small quantities of mineral materials are added to these polymers. The proportion of each component can vary considerably according to the type of biomass.

AN677 – Evolution of CO2 released during pyrolysis of lignocellulosic biomass and its components Private content

Biomass is a renewable source of energy if it is produced in a protected environment, allowing its constant production. The renewable characters present an interest to reduce CO2 emissions. Indeed, when biomass is burnt, it releases CO2 but this one was previously captured in the atmosphere by photosynthesis. Thus, carbon balance is theoretically neutral during one cycle of production-consumption (Figure 2). The thermogravimetry-FTIR coupling is proposed to study the CO2 release from lignocellulosic biomass.

AN676 – Cellulose pyrolysis investigation by thermogravimetry coupled with FTIR spectrometry Private content

Cellulose is a polysaccharide (Figure 1) consisting of a linear chain of several hundred to over ten thousand b(1->4) linked D-glucose units. Cellulose, located in the cytoplasmic membrane of plant cells, is the principal component and therefore the most abundant matter in the nature.
According to the Broido-Shafizadeh model [1] (Figure 2), during cellulose pyrolysis, there is a formation of an activated cellulose with a lower polymerization degree. The thermal degradation of this activated cellulose produce in one hand, volatiles and in other hand, char and gases. Proportions of each pyrolysis product depend of experimental conditions (heating rate, sample mass, gas flow…)

AN675 – Biomass pyrolysis: study of parameters determining the charcoal yield by thermogravimetry

Pyrolysis of biomass products three kinds of components: charcoal, gases and bio-oil. The proportion of each energy product depends on experimental parameters. In order to study the influence of these parameters under the charcoal yield, the reaction of pyrolysis of biomass is simulated by thermogravimetry. In this application, three parameters are studied: the mass of sample introduced in the reactor, the heating rate and the sample size

AN674 – Gas adsorption on catalysts and adsorbents using a quartz tube reactor on a Calvet type DSC Private content

The investigation of gas adsorption on catalysts and more generally solid adsorbents requires a very good interaction between the reactive gas and the powder. The Calvet-type DSC offers the main advantage to work with an open tube detection. This configuration allows the adaptation of different types of experimental crucibles, especially with the possibility of introduction of various types of gas under normal or high pressure. The quartz tube reactor is one option for the applications on catalysts, and more generally for all the adsorption investigations. It makes possible the simulation of the use of a plug-flow fixed bed reactor in heterogeneous catalysis.

AN673 – CO2 capture on aminated solid sorbents by thermogravimetry Private content

The leading contender for post-combustion carbon dioxide capture from coal-fired power plants is the use of amine solvents. Despite the advantages of solvent scrubbing, there are several disadvantages, especially the thermal efficiency losses due to the energy needed to regenerate the solvent by driving off the captured CO2. The use of solid sorbents impregnated with different amine solutions provides a new technological approach for CO2 capture with the absorption capacity of amines and the easy handling of solids without corrosion drawback.
Thermogravimetry is very well adapted to investigate the adsorption and desorption performances of the samples and define the CO2 capture capacity of the corresponding aminated solid sorbents

AN672 – Chemical Looping Combustion by Thermogravimetry

Chemical Looping Combustion (CLC) or also called oxy-combustion is a process that was developed in 1994 by the laboratory of Professor Ishida (Japan) for the CO2 capture. It is a new method of oxidizing fuels without the direct use of either air or oxygen.
The interest of such a combustion is to have a more efficient process for burning fuels (natural gas, coal) with a production of CO2 for sequestration. In order to improve the fuel combustion, more oxygen is brought to the system through metal oxides. So the metal oxide is used as an oxygen carrier to facilitate the fuel combustion and is permanently regenerated and reoxidised.
Thermogravimetry is very well adapted to measure the oxygen transfer capacity (OTC) of the metal oxide sample.

AN671 – Polymorphic behavior of cocoa butter.Influence on chocolate tempering conditions Private content

Cocoa butter is one of the main constituents of chocolate. It is composed of triglycerides (TG) formed mainly of Stearic, Palmitic and Oleic acids. Due to their nodal structure, TG can crystallize under different forms, leading to a polymorphic behavior. Six different polymorphic forms of cocoa butter are reported in literature [1,2], noted from I to VI, by order of stability (VI is the thermodynamically stable form).

AN670 – Heat capacity determination of low density insulation materials by calorimetry

Maintaining acceptable temperatures in buildings (by heating and cooling) uses a large proportion of global energy consumption, leading to a high R&D interest in more efficient insulation materials. Among others, aerogels are interesting low density, low conductivity materials in which the liquid component of the gel has been replaced with a gas. Cp of such an insulation material is a key parameter that describes its aptitude to accumulate heat. As large amounts of sample are needed for such a Cp determination, the C80 calorimeter is perfectly adapted for the measurement.

AN669 – Melting and Crystallization of Phase Change Materials (PCM) by MicroDSC

A phase change material (PCM) is a substance with a high heat of fusion that through melting and solidifying at a certain temperature, is capable of storing and releasing large amounts of energy (see fig 1). Among other energy savings related applications, PCM are used to design more efficient insulation systems. Indeed, these substances can be encapsulated in building materials such as bricks, or other wall, flooring, roofing, and ceiling materials. By successive melting and crystallization, they can damp the day / night outside temperature variations and allow maintaining acceptable indoor temperatures

AN668 – Effect of pressure on the glass transition temperature Tg of an elastomer sample by HP-MicroDSC

When an elastomer is cooled below its glass transition temperature (Tg), it loses its elasticity and becomes brittle. For elastomer O-rings, that are used for sealing purpose, Tg thus corresponds to a lower limit of use. Problems arise when they are used in high pressures systems, as their Tg may be shifted to higher temperatures. The HP-MicroDSC technique is used to investigate the Tg dependence to the pressure

AN667 – CO2 adsorption on basolite C300 studied by coupled volumetry-microDSC

Metal-organic frameworks (MOFs) offer an advantage over classical other porous materials (activated carbon, zeolithes) because their properties can be tailored due to the vast available hoices of metal clusters and organic linkers. Nowadays these structure are foreseen to multiple applications in gas adsorption, like hydrogen storage, selective adsorption of CO2 against CH4, CO2 against H2. The Cu-BTC is chosen as a example of Metal Organic Framework that is available commercially of the demonstration of adsorption studied by Sievert’s technique and
heat flow calorimetry.

AN666 – Cyclic oxidation of metallic alloys by symmetrical TGA Private content

Metallic alloys are frequently subjected to combined environmental attack and mechanical stresses during their actual service life. Their resistance to this complex loading relies partly on their ability to form a protective oxide scale, i.e. an oxide layer with low growth kinetics and high adherence to the alloy. The nature and kinetics of the growth of the oxide layer is ,most of the time, studied using isothermal laboratory tests. When testing the resistance to oxidation of high-temperature materials, the cyclic-oxidation test is used as a reference because it integrates isothermal oxidation kinetics, oxide-scale adherence, mechanical stresses, metallic alloy and oxide creep and the evolution of these properties with time, for conditions close to the actual conditions of use.
Such a cyclic test is run with the symmetrical TAG thermobalance

AN663 – Coupled manometric-calorimetric measurements on Mg-based materials for H2 storage Private content

In recent years, increased efforts are under way to develop materials with reversible H2 storage properties meeting the targets for on-board applications fixed by the US Department of Energy. At this respect, it is fundamental to evaluate with accuracy both the thermodynamic and the kinetics sorption properties of the candidate materials.

On the analytical point of view, the coupling between a manometric technique (PCTPro) and a calorimetric technique (Sensys DSC) is very interesting as both the absorbed/desorbed volume of hydrogen together with the corresponding enthalpy is measured on the same sample.

AN662 – Characterization of a polyimide by DSC Private content

Polyimides are polymers known for their outstanding thermal stability. Indeed, they are well adapted for very tough conditions such as in aerospace, in insulating material or in protective clothing. In the industry, the verification of the resistance of a polyimide requires the knowledge of its thermal profile that is easily obtained with the DSC method.

AN661 – Characterization of PEN (PolyEthylene Naphtalate) by DSC Private content

PolyEthylene Naphtalate (PEN) is a polyester which has the property to be a particularly good oxygen barrier. Hence, it is well adapted to protect compounds susceptible to oxidation. In the industry, to obtain the best properties of the polymer, the thermal handling as to be thoroughly controlled. The DSC test is very useful to determine its thermal profile

AN660 – Characterization of PTFE (Teflon) by DSC Private content

PolyTetraFluoroEthylene, more commonly known under the name of Teflon®, is essentially used for its non-stick properties. In addition, because of its chemical stability and electrical insulation properties, it can be employed in many domains. In order to make the best of its abilities, it is essential to understand the thermal profile of PTFE using the DSC technique.

AN658 – Melting of different polymers (PTFE, Nylon6, PP, PE-LLD, PE-MD) by DSC Private content

When the polymer’s melting temperature is reached, the crystals begin to fall apart. The chains come out of their ordered arrangements, and begin to move around freely. So the knowledge of the melting point of a polymer is one of the basic information for its use. This temperature depends most of all on the type of polymer but also on its crystal forms, including plasticizers or other additives. The melting point of a polymer is easily determined by DSC and measured at the top of the endothermic peak. The dedicated ISO11357-3 standard describes such a melting determination. In this note are given the melting curve of different types of polymers

AN657 – Shrinkage temperature of bovine pericardium tissue for bioprosthetic heart valve application by MicroDSC Private content

Bovine pericardium, a fibrous tissue enclosing the heart of a cow, is commonly used for heart valve replacement. It possesses excellent hemodynamic properties (the ability to move blood) but lacks the same long-term durability of mechanical valves. Glutaraldehyde stabilizes the collagen structure and increases its durability. The stabilizing effects of cross-linking agents such as glutaraldehyde can be assessed by measuring the shrinkage induced by denaturation of tropocollagen of the tissue. So denaturation temperature (DT) coinciding with a temperature at which the collagen shrinks can be used as a measure of the “shrinkage temperature“(ST).
The goal of this study is to measure the ST change, which reflects the stabilizing effect of glutaraldehyde, and to find correlations with the mechanical testing results.

AN656 – Melting of different types of chocolates by DSC Private content

Chocolate is mainly composed of cocoa butter, cocoa paste and sugars. Moreover, the composition could differ from one type of chocolate to another. The dark chocolate contains solid cocoa, cocoa butter and sugar. In the milk chocolate, powder milk is added. In the white chocolate, there is no solid cocoa. Then, the thermal profile is an essential information for the industry to improve the quality and properties of their products, like for example the ability to be solid at room temperature and soft in the mouth.

AN655 – Denaturation of albumin by MicroDSC

Albumins are major proteins which are found in many food products such as egg white, milk or meat. These proteins are able to coagulate under the influence of the temperature. This thermal property is commonly used in food processes, such as in sugar refining to clarify the solutions or as emulsifying and gelling agents.

AN654 – CO2 adsorption into coal measured by PCTPro-E&E Private content

In addition with the research for alternatives to reduce the use of hydrocarbon, every realistic future scenario confirms the continuous use of fossil fuel and thus the release of carbon dioxide (CO2) in the atmosphere. Therefore high research effort is needed to find ways to efficiently store CO2. Unminable coal bed are foreseen as potential solution for a sustainable storage.
This application note shows the results of CO2 adsorption on two coal samples using the volumetric technique

AN653 – Methane adsorption into coal measured by PCTPro-E&E

Coalbed methane is an important source of energy in many countries. In contrast to a conventional gas reservoir, methane is stored by adsorption into pores of the coal. In underground coal mining, it presents a serious safety risk and is one of the leading causes of coal mine accidents. Thus characterization of methane uptake is essential to development of new technologies to harness energy while mitigating environmental and underground mining risks. This application note shows the results of methane adsorption into a coal sample at room temperature and up to 150 bar.

AN652 – Metabolism of mealworms monitored by microdsc

Mealworms are the larva of the mealworm beetle. The mealworm beetles go through four life-stages: egg, larva, pupa, and adult. Mealworms are food for other animals and are sold at pet tores to feed pet reptiles and birds. Worms like other living organisms generate heat when they move and consume nutrients. These result in heat flow measured by a calorimeter.

AN651 – Phase change of lipids under high pressures with HP-microDSC Private content

Copepods are a group of crustaceans found in the sea and nearly every freshwater habitat. They are the smallest, but most abundant living species in the oceans. The way in which these animals survive the very low temperatures in the Antarctic ocean is probably linked with their lipids (or wax esters). High pressure ?DSC allows measuring the thermal properties of these lipids under different pressures, and more particularly their phase change properties.

AN650 – Methane adsorption into zeolite 13X with PCTPro-E&E Private content

The Pressure Swing Adsorption (PSA) has become an alternative to expensive methods of CO2 sequestration in clean fuel burning technologies. The ability of zeolites to selectively adsorb molecules is exploited in methane gas separation and purification. Knowledge about methane and CO2 sorption properties of zeolites (adsorption capacity, pressure regimes and kinetics) is essential to the design of advanced materials capable of capturing methane and CO2 in industrial settings. Among zeolites, 13X is known for its relatively high methane and CO2 capacity. This application note reports on precision measurements of methane adsorption into zeolite 13X over a temperature range 0-50 °C

AN645 – Crystallization of palm oil by DSC Private content

Classically, crude palm oil has to undergo processes to improve its qualities before being proposed on the market. In a first step, an absorption bleaching is performed to produce refined palm oil. This latter is constituted by a liquid phase and a solid phase which could be separated by a fractionation process. This process is based on the crystallization temperature of each phase, that is why, the thermal profile of palm oil should be clearly established. It will be shown that DSC 131 is an equipment perfectly adapted to characterize palm oil in terms of crystallization and quality control.

AN644 – Fish oil (omega-3 fatty acid) oxidation by DSC Private content

Fish oil is a product extracted from several species of fish, like herring, sardines or mackerels.
It is frequently used as a supplement which provides omega-3 fatty acids, well known to regulate cholesterol in the body. For that use, fish oil is usually marketed under the form of softgels for an easier absorption. The determination of fish oil oxidation is very important to understand its mechanisms in the body

AN643 – Influence of pressure on wax precipitation in crude oil with HP-MicroDSC

The presence of paraffin hydrocarbons (C18 – C36) and naphthenic hydrocarbons (C30 – C60) in crude oil, diesels and biodiesels is known to cause wax precipitation at low temperature. Solidified waxes thickens the oil and allow to clog fuel filters and injectors in engines (in the case of diesels or biodiesels) and can cause flow assurance related problems as bad as full pipeline blockage (in the case of crude oil). The prevention of precipitation requires a detailed characterization of the crude oil. On top of its simplicity and fast response, Differential Scanning Calorimetry (DSC) technique has the advantage of allowing operations at the high pressures that can be met in engines or pipelines.

AN641 – Characterization of a polymorphous powder by DSC

The characterization of crystal polymorphisms in drugs is an important point for the pharmaceutical industry. This importance is justified by the fact that the properties of a drug depends a lot on its polymorphic forms. One of the DSC important issue is the qualification of polymorphs and the determination of their stabilities.

AN640 – Thermal stability of therapeutic proteins with MicroDSC3

Antibodies are gamma globulin proteins that are found in blood or other bodily fluids of vertebrates, and are used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses. Antibodies can either neutralize targets directly by, for example, binding to an infection-leading part of a pathogen, or recognize an antigen and tag it for attack by other parts of the immune system. DSC allow to test and understand thermally induced unfolding of immunoglobulin

AN585 – TG FTIR analysis of a carbon fiber Private content

Carbon fiber is most notably used to reinforce composite materials, particularly the class of materials known as carbon fiber or graphite reinforced polymers. A common method of making carbon filaments is the oxidation and thermal pyrolysis of polyacrilonitrile (PAN). The interest of the TG + FTIR is to quantify the non pyrolyzed material and to identify the substances remained with the final carbon fiber.

AN584 – Sintering of a WC + Co pellet

Sintering is a process for making objects from powder, increasing the adhesion between particles as they are heated. It is used with ceramic powders and in powder metallurgy. Sintering is related to diffusion. Tungsten carbide is generally prepared from a powder containing WC and Cobalt as a bind.

AN551 – Hydration of hydratable alumina Private content

The objective of this work is to determine, by thermogravimetry, the difference in the hydration products between the mixtures of hydratable alumina with reactive magnesia and those of hydratable alumina with deadburnt or fused magnesite powder.

AN535 – Pyrolysis of waste tyres Private content

Thermogravimetric method was used to obtain previous information about the thermal decomposition process of the tyre material. Then, the gas generated during the pyrolysis was analyzed by gas chromatography.

AN534 – Analysis of sewage sludges by thermogravimetry Private content

The aim of this paper is to predict the behavior of sewage sludges, the principal waste produced by a sewage treatment plant, in combustion or pyrolysis by thermogravimetric analysis and determine, from that, the parameter PII/(PI+PII).

AN501 – Oxidation behavior of Ti3AlC2 powders in flowing air Private content

the oxidation behaviour of Ti3AlC2 powders has been investigated in air by means of simultaneous TGA-DSC, XRD, Raman spectra, SEM, EDS and BET specific surface measurement to understand the intrinsic oxidation behaviour of this newly developed ternary compound.

AN500 – Improving the oxidation resistance of Ti3SiC2 by forming a Ti3Si0,9Al0,1C2 solid solution Private content

Ti3Si(Al)C2 solid solutions with different Al contents were prepared by substituting a small amount of Si with Al. The results demonstrated that the substitution of Si with 10 at % of Al dramatically improved the oxidation resistance and eliminated TiC. The oxidation behavior of the Ti3Si0,9Al0,1C2 solid solution in air was then investigated at 1000-1350 °C. The oxide layers were dense, adher ent and resistant to thermal cycling.

AN397 – Direct Calorimetric Measurement of Enthalpies of Phase Transitions at 2000°C-2400°C in Yttria and Zirconia

High-temperature differential thermal analysis provided data on phase transitions in zirconia and yttria. The tetragonal form of ZrO2 transforms to the cubic fluorite structure at 2311±15°C with an enthalpy of 3.4±2 kJ/mol. Cubic C-type Y2O3 transforms, probably to the fluorite structure, at 2308±15°C with DH=47.7±3.0 kJ/mol. This high-temperature polymorph melts at 2382±15°C with an enthalpy of fusion of 35.6±3.0 kJ/mol.

AN396 – Study of a Thermite Reaction: Fe2O3 + 2 Al –> Al2O3 + 2 Fe

A thermite reaction (a type of aluminothermic reaction) is one in which aluminium metal is oxidized by an oxide of another metal, most commonly iron oxide. Although the reactants are stable at room temperature, when they are exposed to sufficient heat to ignite, they burn with an extremely intense exothermic reaction. Thermite contains its own supply of oxygen, and does not require any external source (such as air). Consequently, it cannot be smothered and may ignite in any environment (it will burn perfectly well underwater, for example), given sufficient initial heat.
Such a reaction can be successfully be studied by drop calorimetry and its heat measured.

AN380 – Study of a process in off normal conditions : synthesis and decomposition of a diazo compound using the C80 safety vessel. Private content

Before carrying out chemical processes in pilot or production plants, they are subject to a thorough risk analysis. As a part of the risk analysis related to a chemical process, thermochemical data are needed to assess the thermal risks.
The heat of the reaction, the energy released in case of triggering the decomposition reaction, the amount of gas released during a runaway, etc are current questions during a risk analysis in a the chemical industry.
The Swiss Institute of Safety and Security in Basle has designed in collaboration with Setaram a new Mini-Reactor adapted to the study of chemical reactions in order to determine rapidly the data required for a first screening of the thermal risks.

AN361 – Melting of butters and margarine by DSC

Butters and margarines are mainly composed of droplets of water (about a concentration of 16%) in a fatty matrix. The proportions of these components induce the thermal characteristics of the final product. In the industry, determination of their thermal profiles is essential to control their properties in term of “easy-to-spread” and good thermal stability, especially at room temperature. The DSC technique is the ideal tool for such investigations

AN354 – Flexure of epoxy printed circuit boards Private content

Printed circuit (PC) boards are composed of several conducting layers intercalated with epoxy resin prepreg layers. These different layers are pressed together and then heated until reticulation. After reticulation, the thermal expansion coefficient of the PC board is lowered, which prevents metallic wires soldered on it from being broken. In flexure mode, the sample is supported by two parallel edges ; a load is applied on an edge-ended probe which comes to rest in the middle of the sample.

AN352 – Controlled sintering rate of hydroxyapatite (2) Private content

During a test with controlled sintering rate, the heating rate is no more constant but decreases if the sintering rate becomes higher than the preset value. The enlargement of the previous temperature curve shows the temperature profile required to obtain a sintering process at a rate which never exceeds the preset value.

AN351 – Controlled sintering rate of hydroxyapatite (1) Private content

The densification which occurs during the sintering process allows to obtain chemically, thermally and mechanically stable materials. However, the properties of the materials can be still improved by maintaining a constant and not too fast rate of shrinkage during the sintering (see application sheet AN350).
With a specific software package it is possible to simulate a sintering process at a constant rate of shrinkage, the temperature scanning rate being controlled simultaneously.

AN350 – Sintering of hydroxyapatite Private content

Hydroxyapatite, a derivative of a calcium phosphate mineral, is the main inorganic component of vertebrate bone and tooth tissue. Sintered hydroxyapatite ceramics should have medical applications as bone fillers or artificial tooth roots.

AN349 – Sintering of carboniferous shale Private content

Shales are very fine-grained varieties of sedimentary rocks composed of clay, quartz, mica and other minerals. Sintered carboniferous shales can be used as building materials.

AN348 – Sintering of refractory clay Private content

Refractory clays contain only small amounts of fluxing impurities but high amounts of silica, alumina and water and therefore capable of withstanding high temperatures. A refractory clay is considered as a fire-clay if its melting point exceeds 1600°C.

AN347 – Thermomechanical behavior of Ni-based superalloy Private content

For numerous industrial applications, metallic alloys need to have a high resistance to oxidation and corrosion and good mechanical properties, especially between 700 and 1000°C. Among them, Nickel-based superalloys are often used with additive elements such as Chromium to resist oxidation and Molybdenum, Titanium and Niobium to reinforce the initial metallic matrix.

AN346 – Expansion of carbon powder Private content

With the SetsysTMA, it is possible to study the thermomechanical behavior of powder samples. The powder is contained in a crucible, the height and external diameter of which are respectively 20 mm and 10 mm. A flat-ended probe, with a diameter end of 7 mm, is brought into contact with the sample within the crucible.

AN345 – Characterization of glass

The Setsys 92, equipped with a furnace composed of a metal heating coil surrounding an inner silica tube, allows experiments to be carried out up to 1200°C. Thus, glasses can be characterized by different parameters such as : the glass transition temperature, the softening point, the true and average coefficients of thermal expansion ?.

AN344 – Correlation between TMA and DSC data of PET Private content

Glass transition, softening, crystallization, melting are events which cause a change in the characteristic properties of a compound like its heat capacity or its thermal expansion coefficient. These changes can be observed by both DSC and TMA measurements.

AN342 – Glass transition of butadiene-styrene copolymer Private content

The SetsysTMA equiped with a cryostat allows thermomechanical measurements to be carried out at very low temperature (down to -150°C), like the determination of the glass transition temperature of polymeric materials. The glass transition temperature can be defined as the temperature at which a material loses its glass-like rigid properties and becomes more flexible in nature like rubber. This event is accompanied by a student increase of the thermal expansion coefficient of the material.

AN336 – Thermal behaviour of an antibiotic Private content

The knowledge of the behavior of pharmaceutics has a certain importance as it can give information about an eventual decomposition process. For the certification of drug stability certain tests are generally required : a calorimetric experiment will enable the analysis of a substance required for prescribed conditions.

AN334 – Propellant stability Private content

A propellant is generally a mixture of two substances which decompose strongly after ignition. But also in storage conditions this mixture can react very slowly and this process must be surveyed.
It is accomplished by carrying out isothermal experiments with less than one gram of sample at different temperatures (50°C, 60°C, 70°C, 80°C for example). The lost time between two experiments is only 1000s ? 17 min. (see application sheet TN335).

AN333 – Stability of a fertilizer Private content

A fertilizer is generally a medium, which can supply to plant roots elements like N, P, K, Mg, S, Ca..
They are provided under a mixture of NH4NO3, phosphates, P2O5, K2O, MgO, SO3..
When they are stored these mixtures can age. A calorimetric experiment carried out at a fixed temperature can give information about the fertilizer behavior at this temperature.

AN332 – Thermal stability of sulphur Private content

Sulfur is a base compound for the processing of rubber through the vulcanisation process. During this process a fine powdered ?-sulfur is incorporated into the crude rubber then heated. When heated, ?-sulfur will transform into ?-sulfur but this transformation must be avoided for a good vulcanisation because the ?-sulfur aggregates and then creates heterogeneity inside the vulcanized compound. It must be pointed out that the process has been monitored only on using a very slow scanning of 2 K.h-1. All the attempts at higher scanning rate were not successful : it demonstrates that only a very sensitive instrument can be used and that a conventional DSC will not be sensitive enough.

AN331 – Phase transitions in a liquid crystal

With a normal DSC, experiments are generally carried out at a high scanning rate (5 K.min-1). In these conditions the determination of solid-mesophase or mesophase-isotropic liquid transitions can be performed easily. Bus as far as the mesophase-mesophase transitions analysis is concerned, much smaller scanning rate are required (a few K.h-1 or less). The main drawback is that in these conditions CONVENTIONNAL DSC IS NOT SENSITIVE ENOUGH. For these reasons micro-DSC, A VERY SENSITIVE DSC IS OF GREAT INTEREST.
The capability of the micro-DSC of scanning the temperature upwards and downwards is also essential as it can provide information about the reversibility of the different transitions. This facility is especially important with the MONOTROPIC crystals which present mesophases only in the cooling mode.

AN330 – Phase transition of DPPC Private content

DPPC or DIPALMITOYL PHOSPHATIDYLCHOLINE is one of the main constituents of cell membranes. Its dispersion in water presents two endotherms : at low temperature a gel / gel transition involving a molecular packing rearrangement between two gel-state forms, and a gel / liquid crystalline phase transition, involving the melting of the hydrocarbon chains.

AN329 – Melting and gelation of kappa carrageenan by MicroDSC Private content

Carrageenans are extracted from red algae and used in food processing for their gelation properties. This polysaccharide shows an order-disorder transition when heat-treated. The kappa-carrageenan, obtained under aggregating conditions in the presence of K+ ion, shows a single molecular process when heated and cooled. The kappa-carrageenan forms rigid, thermally reversible, high strength gels e.g. dessert gels, petfood gels, air freshener gels. The MicroDSC technique is well adapted to investigate the formation and the melting of such gels

AN328 – Denaturation of an insulin solution Private content

Insulin is the hormone which reduces the blood sugar concentration. It is synthesized by the pancreas. A disturbance in the synthesis leads to diabetes. Thus diabetic people need periodic injection of insulin. This insulin is now synthesized by genetic engineering. Insulin tends to denature and aggregate when it is in injection ready solution. It is of great interest to get information about these processes, as they must be avoided in practice.

AN327 – Stability of human growth hormone Private content

hGH (or somatotropin) is synthesized in the anterior pituitary (hypophysis). A malfunction of the pituitary gland can lead to pituitary dwarfism. As treatment a hGH solution can be injected. An experiment in the temperature scanning mode will provide information about the thermal stability of the hormone : the processes of denaturation and aggregation can then be investigated.

AN325 – Helix-coil transition of plasmid DNA

The helix-coil transition of DNA is often called the “fine structure of DNA melting”. The DSC method is so sensitive that it can detect small structural changes, even those due to cleavage of plasmid DNA with different restriction enzymes and the deletions of small portions of the DNA. Therefore, detailed DSC studies of the helix-coil transition, one of the most important physical properties related to such gene functions as replication, recombination, and transcription, are useful for further understanding of the structure of DNA.

AN324 – Thermal stability of a protease Private content

Protease is a peculiar type of enzyme : its “mission” is to degrade other proteins. It is incorporated into washing powder : it is then the agent which will clean linen stained with blood, eggs,.. As it is to be used in a washing process it is important to know up to what temperature it can withstand denaturation

AN322 – Denaturation of a collagen solution Private content

Collagen is the principal structural protein found in mammalian tissues, such as skin, bone, cartilage, cardiovascular tissue.. Generally extracted from bovine tissue, collagen is used for clinical applications such as hemostatic sponge, wound-dressing material, suture, nerve repair.

AN316 – Analysis of forsterite Private content

This compound is found in large quantity in the earth’s crust and corresponds to Mg2SiO4 formula where magmas are originated from.
With TAG, it is determined that the decomposition of forsterite begins at around 1780°C.

AN315 – Thermal control of carbon fibers Private content

Carbon and graphite fibers are the only ceramic materials made by one chemical element. Their properties are well known : low expansion coefficient, good resistance to thermal shocks, excellent chemical resistance, use at very high temperatures, easy to use, high thermal conductivity.

AN314 – Supercooling of a monocrystal Private content

The neodymium doped LaMgAl11O19 compounds are used in LASER manufacturing.
These compounds melt at high temperatures (around 1900°C). As crystal elaboration is carried out from a melted state bath, temperature must be well known. From a crystal nucleous soaked in the bath, a very slow stretching is carried out. The knowledge of the crystallization as well as possible supercooling must be determinate.

AN313 – Liquid – solid phase diagram Private content

Liquid-solid phase diagrams can be calculated using thermal analysis techniques.
In the field of very high temperatures, mixing of ceramics with a high melting point can be investigated.
Like alloys, mixtures of ceramics have almost the same applications but at higher temperatures. For example, in some new motors cars, ceramics are introduced to protect the hot zones in the cylinders.

AN312 – Silicon carbide Private content

Silicon carbide have good properties (tensile strength, ..) for a large range of temperatures.
These materials have transformations at high temperature, which can modify the mechanical properties.

AN311 – Stability of uranium oxide at 2000°C Private content

UO2 powder used as nuclear fuel is mixed with gadolinium oxide (Gd2O3).
Gadolinium oxide is a neutron collector. The normal working temperature of these elements is about 1600°C but we can measure the properties and behavior of these material in the case of a temperature raise up to 2000°C.

AN310 – Study of boron-titanium ceramics Private content

Boride based ceramics also have high melting point. They have particularly interesting applications in reducing gases or under vacuum at very high temperature. Titanium boride (TiB2) is especially required due to its refractory properties, its hardness and its electrical characteristics.
It is used as cutting tool and for aircraft noses as well.

AN309 – Melting of metallic carbides Private content

Metallic carbides are known to resist changes at very high temperatures. They have excellent characteristics of chemical inertia and mechanical resistance.
It is important to study the thermal behavior of such products for their applications.

AN303 – Cycle temperature up to 1750 °C Private content

The temperature of the furnaces of the TAG is scanned by the controller.
Scanning rates when heating or cooling can be set from 0.01 K.min-1 up to 99.99 K.min-1.
Studying alloys requires a high temperature limit (1750°C) with accurate heating and cooling scanning rates in order to determinate melting and crystallization points and also the evolution of these points after several cycles.

AN302 – Decomposition of calcium oxalate Private content

Inorganic compounds, like oxalate, have well known decomposition reactions. With the calcium oxalate, the following reactions occur when heating up to 900°C.
CaC2O4, H2O –> CaC2O4 + H2O –> CaCO3 + CO –> CaO + CO2

AN301 – Gas desorption by thermogravimetry Private content

Sensitive materials like “silicon plates” are prepared under controlled atmosphere. Gas adsorption depends on the pressure and gas nature. When heating, theses gas can be desorbed and quantified thanks to thermogravimetry.
The TAG must be used in a symmetrical configuration, to get a very high sensitivity of less than 1 µg. To be sure of the results, three cycles of temperature must be run ; the difference between the third and the second runs gives balance stability and measurement reproducibility.

AN299 – Phase transitions in zirconium alloys Private content

Alloys have transitions or phase transformations. These transformations can be detected only by DTA, so a good sensitivity and a controlled atmosphere are needed to avoid others effects (oxidation, nitridation, ..). When a transition occurs it corresponds to a variation of heat capacity which is detected by a change of baseline on the DTA curve. This transition also changes the properties of alloys.

AN298 – Hydrogenation of “dead” catalysts Private content

Some catalysts can be regenerated. A quick thermal analysis is able to separate the different compounds absorbed when being used and choose the appropriate cycle of regeneration. Such products are expensive and regeneration has to be done in the best conditions.
To provide products like sulfur which are reacting with platinum at low concentrations, a “protected probe” without exposed platinum can be utilized up to 1750°C.

AN297 – Decomposition of sulfate Private content

This classical example shows dehydration of pentahydrate copper sulfate CuSO4, 5H2O with argon sweeping at a rate of 1 l/h.
TGA and DTA curves are plotted without any digital correction.
Note : levels, separating the successive mass losses, are clearly horizontal, especially at the beginning of the heating. The DTA curve is stable.
Symmetrical configuration is especially efficient when the available sample mass is small or when the variations in the expected mass are low.

AN295 – Thermal strength of carbon fiber Private content

Silicon carbide fibers are known for their tensile strength and also thermal behavior at high temperature. It is used as fiber in composite materials.
SiC fibers are analyzed in oxidizing atmosphere, they are heated up to 1500°C during 10 hours under air flow, to simulate, for example, an entry into the earth’s atmosphere of a space shuttle. Mechanical properties can also be evaluated after this test.

AN294 – Kinetic reaction : carbon hydrogenation Private content

A reaction can be studied with thermogravimetric method to determinate kinetic parameters. For one temperature, the derivative of the mass loss (DTG), usually constant, gives the speed of the reaction, the total mass loss, and the conversion rate.
The active gas option is used to introduce hydrogen into the furnaces and to get a rapid atmosphere change. As platinum becomes brittle at high temperatures, under hydrogen, tungsten-rhenium thermocouples and tungsten crucibles are utilized.

AN293 – Determination of free water in milk powder by TG-DSC Private content

Milk powders have different composition for various utilization from baby milk to diet milk, but all include water, under the form of humidity or bound with other constituents.
By thermogravimetric analysis, these two kinds of water can be separated.
Stale milks and climate conditions modify these concentrations, and this analysis makes it possible to control these evolutions.

AN286 – Enzymatic reaction : amylase + maltose Private content

The µDSCIII can be used at two levels for checking enzymes : defining the temperature limit of use of the enzyme (see application note AN285), and also for simulating an enzymatic reaction. Mixing vessels, consisting in two inlet tubes and one outlet tube, are available. In the example the reaction between a fungal gluco-amylase solution and a maltose solution is investigated, giving a transformation of the sugar.

AN285 – Thermal denaturation of an enzyme (fungal gluco-amylase) Private content

Enzymes are specific catalysts of biochemical reactions. They are usually proteins which are denatured by temperature. A temperature scan gives a knowledge of the enzyme stability and thus of its working temperature range. For example, fungal gluco-amylase is used in the fermentation industry for enzymatic reaction (see application note AN286). The Micro DSCIII enables the thermal stability of the enzyme and the optimum temperature for its use to be determined.

AN283 – Thermal denaturation of animal proteins Private content

Differential scanning calorimetry analysis can field information on the composition of multi-component systems, frequently encountered in foods, such as muscles. Muscle is a complex system consisting of different classes of proteins (myofibrillar, sarcoplasmic, collagenous). The DSC thermogram of the whole muscle shows the contribution of the proteins by their denaturation and enables identification of the main protein components (actin, myosin, sarcoplasmic proteins). Variations in this « fingerprint » of the muscles can be observed on the thermograms due to differences in the structure of proteins, different amounts of protein components, the state of the muscle. The µDSCIII is especially adapted for this type of analysis.

AN282 – Detection of alpha-lactose in whey powder Private content

Dry milk and whey powder contain amorphous lactose. But the storage of these products under high relative humidity induces lactose crystallization (a-lactose monohydrate). This produces a dense powder, which becomes unusable for consumption. The DSC technique enables the a-phase to be detected by measuring the dehydration of the a-lactose monohydrate. This is a very easy and useful test for checking of whey powder and dried milk.

AN281 – Freezing of an extract of liquid coffee Private content

For the frozen products, the DSC method can provide four different characteristics : the temperature at the beginning of freezing (especially for the solutions), the amount of ice at given temperature (also for the solutions), the temperature at the beginning of melting, the detection of possible phenomena of recrystallization. The temperature at the beginning of freezing is especially interesting for the industrial operations of extract freezing. It also defines the temperatures range of freeze drying for which the completely frozen water is evaporated under vacuum. In the example, the temperature of freezing of an extract of liquid coffee is measured.

AN280 – Oxidation of edible oil under pressure Private content

The main problem caused by lipid oxidation is the formation of volatile compounds, which smell. This limits the time of conservation of different foods. When food containing lipids is heated, the temperature increases the degree of oxidation. This is especially true for edible oils used for frying. The pressure of oxygen has also an important effect on the kinetics of the oxidation reaction. The high-pressure crucible with gas flow under pressure is used in the DSC121 to characterize the effect of oxygen pressure on the oxidation of peanut oil.

AN278 – Determination of the Solid Fat Index (SFI) of Chocolate by DSC

The melting curve of a fat is generally complex: for a given fat, there is not a melting point, but more a melting range. In processing fat, it is also interesting to know, for a given temperature, what is the amount of fat melted. The DSC technique is now widely used to determine solid-liquid ratios in fats, called the Solid Fat Index (SFI). This method is based on measuring the heat of fusion successively at different temperatures. By reference to the total melting heat, the fraction of fat melted is determined. This technique is faster than dilatometry, and give results comparable with NMR. DSC gives the possibility of tempering the fat at different temperatures prior to index determining.

AN277 – Characterization of palm oils at different temperature scanning rates by MicroDSC Private content

Palm oil is mainly constituted of esters of glycerol and fatty acids named glycerides. The composition of glycerides in oil is an important characteristic to control its quality. This composition can be determined following the specific phase transitions between polymorphic forms and solid-liquid phases of the constituents. It is shown that MicroDSC VII Evo is an equipment perfectly designed to characterize palm oil in terms of research and quality control.

AN276 – Tripalmitine melting : influence of heat treatment

When measuring melting points of fats or oils, some anomalies can be detected due to supercooling, but mainly to the fact that solid triglycerides exist in different crystalline forms (polymorphism), each of them with a different melting point. The crystalline form depends on the rate of cooling or heating, on the storage conditions (time, temperature…) These crystalline forms have an influence on the functional properties of the fat : e.g. butter spreading, milky aspects of oils.

AN275 – Melting and solidification of cheese Private content

INTRODUCTION

Cheese is the curd of milk, basically a gel of casein. It contains mainly water, fat and proteins, the ratio of which depends on the type of cheese. If the curd is heated up to melting, a cream of cheese is obtained. The DSC test can give information on the thermal processing of cheese, also about possible storage at low temperature (refrigerator). On the example, a sample of cheese cream is cooled, then heated to show the thermal transformations in the product.

 

EXPERIMENTAL

Samples:

  • A soft cheese and a hard cheese

DSC 131 Evo experimental conditions:

  • Atmosphere: Nitrogen, atmospheric pressure
  • Sample mass: about 50 mg in a 100µl
  • sealed aluminum crucible

Experimental procedure:

  • The temperature is scanned from -50°C up to 40°C at 5°C.min-1.
Image1

Figure 1: Heating and Cooling thermograms of the hard cheese

 

Image2

Figure 2: Heating and Cooling thermograms of the soft cheese

 

RESULTS

When the samples of cheese are heated, different endothermic peaks corresponding to melting of fats and water are seen. When cooled down to – 50°C, a large exothermic peak is observed corresponding to the freezing of water contained in cheese.

This DSC test indicates what is the lowest temperature for a temperature controlled storage without the cheese freezing. Hard cheese can be stored at lower temperature compared to soft cheese.

 

 

AN274 – Melting of different sugars by DSC Private content

Different types of sugars are present in food products (sucrose, fructose, maltose, saccharose..). Many of them are used in the food industry, as a powder or liquid. During food processing, they are heated, cooled, quenched according to different heat treatments. The DSC test is useful in this case to characterize the thermal behavior of the sugar when heated or cooled, to know if the sugar is in a crystalline or amorphous form according to the preparation. In the example the melting of three different sugars is measured.

AN273 – Melting of an edible oil after different processes Private content

INTRODUCTION

Fats are either liquid at room temperature (oils) or plastic (solid fats). Crude fat or oil undergoes a series of manufacturing processes before it is marketed. These include treatment with alkali to remove impurities, dehydration, hydrogenation, fractionation.. Depending on the treatment, the consistency of fat is different. The DSC method, by measuring the melting of the triglycerides contained in the fat, shows what is the effect of the manufacturing process on the crude fat.

AN263 – Liquid adsorption : an hydrocarbon (C32H66) and butanol (in heptane) on a powdered coal Private content

The surface reactivity of powdered coal depends on the thermal treatment during its preparation. The characterization of the surface is done through the desorption of solvents with different structures. For such an investigation, a special flow cell (see application sheet TN262) is used.
N-heptane is the carrier liquid, and butanol and C32H66 (both dissolved in n-heptane) are to be absorbed on the powdered coal, which has been heated under inert atmosphere at 260°C.

AN261 – Wetting and gelation : Potato starch in water Private content

Starch is a vegetal polysaccharide from different origins (potato, maize,..). It is industrially used in many foodstuffs, especially in fast cooking products. When mixed with water at low temperature, wetting of starch occurs. When heated in water, a gel is formed. The temperature of gelation depends on the origin of starch. The mixing vessel with membrane is used to investigate the wetting and gelation of starch in water.

AN259 – Organic reaction : Formol + Butanal in Soda Private content

The reaction between two organic liquids most often liberates a large amount of heat. In an industrial reactor, when the reaction takes place, large volumes of each component are involved. It is important to know what will be the heat evolved and the rate of reaction, in order to drive correctly the reactor.
The calorimeter is well adapted for this type of simulation. As many reactions occur in alkaline medium, the mixing vessel with metallic membrane is indicated for these experiments, like the reaction between formol and butanal in soda.

AN257 – Hydration : calcium sulfates (plaster and anhydrite III) in water Private content

Four forms of calcium sulfate are known : dihydrate : CaSO4, 2H20 (gypsum), hemihydrate : CaSO4, ½ H20 (plaster) and two anhydrites CaSO4 : natural and insoluble anhydrite and soluble anhydrite III (obtained by heating plaster up to 200°C).
Plaster and anhydrite III, which are soluble in water, are used in the building industry, because of their setting properties.
The reversal mixing vessel is particularly well adapted for the investigation of plaster setting. Water and plaster are initially separated in the vessel, then mixed.

AN256 – Dissolution : Potassium Chloride KCl in water Private content

The dissolution test is a standard one for the mixing calorimetry. It is a way to check the calibration of the calorimeter. The dissolution of potassium chloride in water is used as a reference test.
With the C80 calorimeter, the best results are obtained with the reversal mixing vessel.

AN255 – Neutralization : Edible oils by soda Private content

Raw edible oils contain a certain amount of free fatty acids, which have to be neutralized before their use. In industrial plants, an excess of soda is added to neutralize the free acidity. The problem is the adjustment of the amount of soda to be added, knowing the oil acidity. The simulation of the operation is made in a calorimeter on different edible oils, using the reversal mixing vessel.

AN254 – Polymorphism detection : Active drugs (forms 1 and 2) in soda

The determination of drug polymorphism is an important problem for the pharmaceutical research. Depending on the polymorphic form present in a drug, its characteristics can be very different. The detection of the polymorphic forms is not easy. DSC has been used with some success, but cannot be used for all products (thermal stability limitation). As the polymorphic forms have different behaviors especially dissolution properties, the calorimetric test of dissolution is used to investigate their differentiation.

AN253 – Binding : carrageenan in mineral salts solutions Private content

Carrageenan is a polysaccharide, largely used in the food industry especially for its gelation properties. In solution, the polysaccharide exhibits ion selectivity. A specific site binding is observed with certain ions in preference to others. The calorimetric test is used to measure the heat of binding of iota carrageenan with different ions from mineral salts.

AN251 – Dehydration : hydrated salts Ba(OH)2 – 8H2O and AlCl3 – 6H2O Private content

The heats involved during dehydration processes of some mineral compounds can be used for energy storage as the heat of vaporization of water has a high value (? 42 kJ.mol-1). Hydrated salts are especially interesting for such applications. Calorimetry is the ideal method for testing the capacity of energy storage and for determining the range of temperature in which the transformation occurs. The gas circulation normal pressure vessel is used for such an investigation. Water vapor during dehydration is evacuated through the tube.

AN249 – Vapor adsorption : Benzene on a zeolite Private content

Many solid porous compounds, especially zeolites, are well known for their adsorbing properties. In order to measure their adsorption capacity, a special experimental set-up has been designed for the C80 calorimeter.
This device allows the characterization of the adsorption of vapor on a solid under reduced pressures. The liquid to be absorbed is initially frozen then kept at a well-defined temperature, determining a well-known vapor pressure.
This vapor is absorbed on the solid, previously regenerated under vacuum. The solid is contained in a vacuum high-pressure vessel. An example of the use of such a device is given by the adsorption of benzene vapor on a zeolite.

AN248 – Decomposition under pressure : Coffee in argon (20 bars) Private content

The knowledge of thermal stability of products to be transformed under heating is of the first importance. This is often the case in food industry where raw products are heated in reactors, e.g. coffee when roasted.
It appears that during the roasting operation, large quantities of heat are liberated.
In order to determine the risk of thermal hazard or spontaneous ignition of the product, a simulation is operated by calorimetry, using the vacuum high pressure vessel. This vessel enables a pressure of inert gas (20 bars) to be applied during the reaction, in order to simulate the real industrial conditions.

AN246 – Solubility : potassium and sodium chlorides in water Private content

The standard high-pressure vessel is well adapted for the heating of solutions above 100°C. An interesting application is the detection of the limit of solubility of salt mixtures. The corresponding temperature is detected when the calorimetric signal changes abruptly, showing the end of the thermal effect of dissolution. In the example a mixture of potassium and sodium chlorides in water is investigated at different ratios.

AN245 – Decomposition of sodium borohydride NaBH4 Private content

In chemical industries, the determination of the thermal hazards or decomposition risk for organic products is one of the most important experimentation to be run before any transformation or storage of the products.
The thermal methods give an interesting mean of experimentation and simulation for such a determination. The organic sample set in a closed standard high pressure vessel is heated quickly at a fixed temperature and the thermal behavior of the sample is observed by recording the calorimeter signal.

AN244 – Solid-solid reaction : Hydrated baryta + potassium nitrate Private content

The storage of chemical heat consists in using the reversible endothermic and exothermic reactions of a chemical equilibrium. This is the case of the reaction between two solids materials : hydrated baryta and potassium nitrate :
Ba(OH)2 – 8H20 + 2KNO3 <--> Ba(NO3)2 + 2KOH + 8H20.
The calorimetric standard vessel enables the investigation of a large amount of mixture at low heating or cooling rates. In order to have a better homogeneity of the solid mixture during the reaction, the reversing mechanism of the calorimeter can be used to shake the mixture.

AN240 – Heat capacity : coal Private content

The heat capacity determination by the calorimetric method is well known and very easy to run. The sample is heated in the calorimeter, and the heat flow detected by the heatflux transducer is directly proportional to its heat capacity. In practice, two successive tests are necessary : one test with empty vessels on both sides (measure and reference), and a second test with the sample in the “measure” vessel, the “reference” vessel remaining empty. The experimental conditions must be strictly identical for both experimentation. The heat flow deviation between the two curves characterizes the variation of the sample heat capacity versus temperature.

AN239 – Transitions : Ammonium Nitrate Private content

The temperature range of the C80 calorimeter is large enough to investigate some phase changes or transitions in materials. The experimentations are run on large amounts of sample, with low heating rates. That gives precise quantitative measures, and solves also the problem of sampling for some inhomogeneous materials.
Using a standard vessel, a sample of ammonium nitrate is heated at 0.2K.min-1 for detecting different characteristic transitions.

AN238 – Melting : hydrated ferric chloride FeCl3 – 6 H20 Private content

The latent heat is the energy evolved by a material when it undergoes to a structure change. The effective storage of this heat requires the use of materials with large melting heat, which can be recovered during solidification. For latent heat storage below 130°C, hydrated salts are frequently used. Mostly they are tightly encapsulated in order to prevent evaporation or contamination of the material.
A glass ampoule containing a large amount of FeCl3 – 6H2O is placed in a standard vessel, and the melting of the hydrated salt is easily investigated.

AN234 – Determination of adsorbed and structure water in a catalyst Private content

Thermogravimetry is frequently used in characterizing the natural or synthetic types of catalysts and zeolites, and especially in distinguishing the loss of adsorbed and structural (hydroxyl) water. For their use as adsorbents or catalysts, it is also important to know how the dehydration process occurs. An example of determination of adsorbed and structural water in a catalyst is shown hereunder.

AN233 – Adsorption of benzene on a zeolite Private content

Isothermal calorimetry is well adapted to measure the adsorption capacity of zeolite for different compounds. The incremental vapor pressure method is used in the following example, showing the adsorption of benzene on a zeolite. The experimental adsorption device, described on application note TN231, allows running such an investigation.

AN232 – Adsorption of water vapor on a zeolite Private content

Zeolites are hydrated silicates of aluminum, and either sodium or calcium or both, of the general formula Na2O-AI2O3-nSiO2.xH2O. They are well known for their adsorption and catalyst properties, used more and more for industrial applications. An example of adsorption of water vapor on a zeolite is given to show the possibilities of the experimental set-up described on application note TN231. The amount of adsorbed water depends on the type of zeolite, the temperature and the pressure of water vapor. The calorimetric test is very useful to measure the adsorption capacity of a zeolite and to compare the efficiency of different zeolites.

AN230 – Adsorption of oxygen on nickel oxide Private content

The CALVET microcalorimeters are particularly well adapted for the determination of differential heats of adsorption of reactive gas on solid catalysts (see P.C. GRAVELLE, Catal.Rev.Sci,1977, 16(1), 37-110).

A well-known volume of reactive gas is injected on the catalyst. The adsorbed volume is evaluated and the heat of adsorption measured. Then the curve of variation of the heat of adsorption versus the degree of surface coverage can be drawn.

AN229 – Adsorption of carbon monoxide on palladium catalyst Private content

The platinum catalyst, described on the application note AN227, has relatively large amount of platinum. In order to give a limit of detection to the DSC-GC combination device, an experimentation has been run on a catalyst containing only 0.2 % Palladium (support : alumina), for the adsorption of carbon monoxide (10% in helium). The effect of metal dispersion on the support is also investigated for a catalyst containing 0.75% Palladium.
Helium is used as a carrier gas. Catalysts have been initially preheated under H2 at 250°C, then desorbed under helium.

AN228 – Temperature programmed desorption of a platinum catalyst Private content

After adsorption of a gas on a catalyst, it is interesting to know what type of adsorbed species have been formed. One mode of investigation is to desorb the catalyst by heating and record the desorption thermogram : that is the temperature programmed desorption. On the thermogram, peaks will appear corresponding to the different species formed during the gas adsorption. An example is given by the desorption of a platinum catalyst after hydrogen adsorption (see application note AN227).

AN227 – Adsorption of hydrogen on a platinum (6,3 %) catalyst Private content

The use of the DSC-GC combination (see application note AN226) is illustrated by the investigation of hydrogen adsorption on a platinum catalyst, called Eurocat. The catalyst contains 6.26% platinum deposited on silica.
Hydrogen is diluted to 5.4% in argon, and injected on the sample through an injection loop (0.5 ml), in the carrier gas (argon). Before adsorption investigation, the catalyst is initially pretreated in the DSC by heating under hydrogen up to 450°C, and held at this temperature during 2 hours. Then, the surface of catalyst is completely desorbed under a flow of argon, before cooling at the temperature of investigation.

AN226 – Gas adsorption and gas analysis (gas chromatography, mass spectrometry) Private content

The combination of thermal analysis with evolved gas analysis is frequently used in order to characterize the exhausted gases of a reaction. Such a connection requires a continuous circulation of gas through the instrument, with an easy fitting of the EGA apparatus. The open structure of the Calvet DSC111 is particularly interesting for such a combination. The quantitative measurement of both heat evolved by a sample and the amount of gas emitted is made possible, giving a great interest for the better comprehension of the reactions occurring during the experiment. This is particularly powerful for gas-solid interactions, like adsorption in the catalysis field. Two types of combination are described : DSC-gas chromatography and DSC-mass spectrometry using the silica reactor (see application note TN225).

AN224 – Oxygen interaction with coal before combustion Private content

The thermogram of coal combustion (application note AN214) shows two steps in the oxidation reaction. The first peak has been often associated with the combustion of volatiles.
But when a coal is maintained under oxygen at 110°C in a thermobalance, a mass increase is detected, corresponding to an oxygen adsorption on coal. The result of this interaction is the modification of coal structure and the formation of complex compounds. The first peak detected by DSC seems to be associated to this coal transformation before the burning of fixed carbon.

AN223 – Proximate analysis of a coal Private content

The proximate analysis, as described in application sheet AN222, allows classifying a coal and gives information for its industrial use. Coal is particularly classified according to its volatiles content : anthracite (8 to 18 %), semi-bituminous (18 to 26 %), bituminous (26 to 40 %), semi-bituminous (40 to 50 %).
The thermogravimetric test allows giving a rapid result for a coal.
All the operations heating and gas switching are automatically achieved by the controller associated with the thermoanalyzer.

AN222 – Proximate analysis of anthracite Private content

Anthracite is a higher species of coal, which contains a low content of volatiles. A rapid characterization of anthracite is obtained by the proximate analysis. This industrial determination gives the contents of moisture, volatiles, fixed carbon and ash in the sample.
The proximate analysis is easily achieved by thermogravimetry according to the following scheme :
– Heating to 110°C and isothermal level during 5 minutes => moisture
– Rapid heating to 950°C under inert gas and isothermal level during 10 minutes => volatiles
– Switch from inert gas to oxygen at 950°C => fixed carbon
– Test residue => ash

AN221 – Melting of coals ashes Private content

Melting of ashes is of a high importance in the use of coal. According to the conditions of use, it can be interesting or forbidden. Melting of ashes depends on their chemical composition, and also the type of atmosphere in which melting occurs.
A coal has rather fusible ashes when the melting point is about 1300°C. If melting does not occur below 1500°C, ashes are said refractory.
Setsys DTA is used to characterize the melting of two ashes.

AN219 – Adsorption and desorption of an hydrocarbon (C32H66) and butanol (in n-heptane) on a powdered coal Private content

The surface reactivity of powdered coal depends on the thermal treatment for its preparation. The characterization of the surface is done through the adsorption of solvents with different structures. For such an investigation, a special flow cell (see application note TN220) is used.
n-heptane is the carrier liquid, and butanol and C32H66 (both dissolved in n-heptane) are to be adsorbed on the powdered coal, which has been heated under inert atmosphere at 260°C.

AN218 – Heat capacity of powdered coke Private content

If the calorific value of coal is of first importance, the value of the enthalpy is also necessary to establish the heat balance of the system under study.
By the isothermal drop method, the total heat necessary for heating the sample from a temperature T1 (generally ambient temperature) up to higher temperature T2, is measured.
The method is used for measuring the enthalpy of a powdered coke (30-40 mesh) at different temperatures.

AN217 – Oxidation of bituminous shales with various oil contents Private content

The interest of bituminous shales is growing, due to its organic part. But the cost of oil extraction from shale is a limitation. Some investigations are done in order to use the oil shale without treatment, as a fuel, like in cement industry. In this case, it is necessary to determine the range of temperature in which combustion of the organic part occurs, and also the heat evolved during combustion. The calorimetric test is well adapted to give those two experimental values. The CALVET HT1000 calorimeter is used for investigation of large samples at low scanning rates. Two bituminous shales with different oil contents are investigated.

AN216 – Comparison of bituminous and coal shales oxidation

The oil of bituminous shale, as described on application note AN217, burns in three different steps between 100°C and 500°C.
Coal shale is often used as a fuel in cement industry.
The same mass of sample is heated under oxygen in the CALVET HT1000 calorimeter. Oxygen is introduced in the crucible by means of a small tube plunging in the sample.

AN215 – Pyrolysis of a coal Private content

According to the temperature of the test, different types of products are obtained during the pyrolysis of coal : gases, chars, condensable products (water, ammonia), benzols and coke as final product above 1000°C. The production of gases (hydrogen, methane, ethylene,..) begins at about 350°C. After this distillation, an intermediary coke is obtained at about 600°C. The formation of this compound and the production of gases is investigated by DSC, in an inert atmosphere.

AN214 – Combustion of coal Private content

In the case of coal products, the calorific value is usually determined with bomb calorimeters. This type of method is accurate, but does not yield information on the combustion reaction. Differential Scanning Calorimetry allows another approach of the combustion investigation. The heat of combustion is measured, referring to a standard coal with a well known heat content (in this case coal 7 DE from DSM Holland).

AN213 – Combustion of coke with different sample masses Private content

Coke is especially used in steel industry and in metallurgy. Its calorific content varies from 6500 to 7500 cal.g-1, and the combustion gives very few ashes.
The combustion of coke can be investigated by DSC. But, as the sample masses are generally little, it is necessary to know what is the influence of the mass on the determination of the heat of combustion.

AN212 – Combustion of carboneous products Private content

Coal is particularly characterized by its calorific value which essentially depends on its carbon and volatile contents. The combustion of coal occurs on a wide range of temperature (from 200°C up to 600°C). Coke, which is a high carbon content product, burns at higher temperature, with only a step of combustion. Carbon graphite is an ideal case of combustion, the reaction yielding only water and carbon dioxide.

AN208 – Thermal stability study by SENSYS DSC : influence of pressure on the thermal stability of azodicarbonamide

Azodicarbonamide formula is NH2 – CO – N = N – CO – NH2. The compound belongs to the family of azo dyes. Azodicarbonamide decomposes at about 200°C. But the decomposition phenomena largely depends on the pressure above the sample. Different tests are run in an open crucible, a sealed crucible and a controlled high pressure crucible, in order to show that the pressure on the sample has a great influence on the decomposition rate.

AN206 – Decomposition of diethylenglycol -Na diluted in diethylenglycol Private content

Diethylenglycol is largely used in organic chemistry due to its excellent solvent properties. The sodium derivative of diethylenglycol is an intermediate for organic synthesis. Diluted in diethylenglycol, diethylenglycol-Na has a relatively good thermal stability up to 250°C. Decomposition of DEG-Na at different concentrations in DEG is investigated in sealed crucibles. The pressure developped during decomposition is about 50 bars or more.

AN205 – Decomposition of a peroxide in solution in cyclohexane Private content

Peroxides are known as very unstable materials : concentrated material may react explosively with combustible materials. The knowledge of the thermal stability of such a product must be well known before its use in organic reactions, or also storage. A sample of peroxide in solution in cyclohexane is investigated in a sealed crucible.

AN203 – Decomposition of polyacrylonitrile Private content

Polyacrylonitrile (CH2 – CH -)n is mainly transformed in synthetic fibers or
l used for elaboration of different copolymers.
CN Polyacrylonitrile is thermally stable for
medium temperatures. Above 250°C, it undergoes a very strong decomposition. The kinetics parameters of the reaction are determined according to the FREEMAN-CAROLL method.

AN202 – Decomposition of paranitroacetanilide Private content

Paranitroacetanilide (NO2 – C6H4- NH – CO – CH3) is obtained by nitration of acetanilide, in concentrated sulfuric acid solution.
Hydrolysis of paranitroacetanilide is thermally stable up to 270°C. The kinetics parameters of the decomposition are determined according to the FREEMAN-CAROLL method.

AN201 – Decomposition of nitrocumene Private content

Nitrocumene (NO2- C6H4 – CH – (CH3)2) is an organic liquid used in synthesis. This liquid is thermally stable at medium temperatures and begins to decompose at about 250°C. The kinetics parameters of the decomposition are determined according to the FREEMAN-CAROLL method.

AN200 – Decomposition of 2,4 – dinitrotoluene at various scanning rates Private content

2,4-dinitrotoluene (CH3 – C6H3 – (NO2)2), obtained by nitration of toluene, is an intermediate for organic synthesis and especially used in mixtures of explosives.
2,4-dinitrotoluene has a dangerous fire hazard. The decomposition of this material is investigated at different scanning rates, and the kinetics parameters are determined according to OZAWA and KISSINGER methods.

AN198 – Hydration of cement (C3S) at different temperatures Private content

The setting time of a cement has to be well known in order to determine its industrial applications Tricalcic silicate (C3S) is the active component of cements, giving a high resistance which obtained rapidly. A thermal investigation of C3S hydration by means of calorimetry allows us to determine the setting time and the kinetics of hydration, and also the influence of temperature on the parameters.

AN197 – Hydration of plaster at different temperatures Private content

The influence of temperature on the hydration of plaster is well known to plasterers in view of the differences they observe between the behaviour of their material in winter and summer.
Also it appears that, above a well defined temperature, the water-plaster mixture gives a paste which does not set for several hours.
The calorimeter C80 is used for studying the influence of temperature on plaster setting.

AN196 – Hydration of two calcium sulfates (plasters and anhydrite III) Private content

Four forms of calcium sulfate are known : dihydrate CaSO4, 2H2O (gypsum), hemihydrate CaSO4, ½ H2O (plaster) and two anhydrites CaSO4 : natural and insoluble anhydrite and soluble anhydrite III (obtained by heating plaster to 200°C) .
Plaster and anhydrite III, which are soluble in water , are used in the building industry, because of their setting properties.
Calorimetry is an interesting method for studying the setting of calcium sulfates.

AN195 – Heat content of crude Portland cement Private content

The problem of power consumption is becoming increasingly important in many industries, particularly those which use high temperature furnaces. So it is important to be able to establish total or partial heat balances for any given system.
The 1500°C calorimeter allows us to measure the heat which must be supplied to a system, for example to run clinkerisation of crude Portland cement.
The sample, thermostated at ambient temperature, is dropped into the calorimeter which has been stabilized at 1430°C.

AN194 – Heating of crude in a (CO2 + H2O + N2) atmosphere Private content

Crude cement is industrially heated in rotary kilns where the atmosphere is a gaseous mixture of carbon dioxide, water vapour and nitrogen.
In order to simulate the heating of the cement in the kiln, the measurement is carried out in the high temperature Calvet calorimeter in the presence of a gaseous mixture containing 25% CO2 , 10% H2O vapour and 65% N2 (see calorimetric device below).

AN193 – Baking of crude Portland cement Private content

After preparation of the raw materials (lime, clay, marl,..) in proportions dependent on the process selected, paste, powder or granules are introduced into the rotary kiln so that the mixture may be gradually heated to the clinkerisation temperature, that is to say to the temperature at which partial melting occurs, about 1450°C.
Differential thermal analysis is used to simulate the conditions existing during cement manufacture and to characterize the phyzical and chemical processes which occur in the cement when it is heated to 1500°C.

AN192 – Dehydration of calcium sulfate CaSO4, 2H2O (gypsum) Private content

Gypsum is used to prepare plaster products. Small amounts of gypsum are also contained in cements. Because of the characteristic nature of the gypsum peaks, the dehydration studies can be employed for the quantitative and qualitative determination of the components in any mixtures (dihydrate, hemihydrate).
Dehydration of gypsum occurs in two stages :
CaSO4, 2 H2O –> CaSO4, ½ H2O (plaster) –> CaSO4 (anhydrite)

AN191 – Heat capacity of crude cement and clinker Private content

Heat capacity is a very important thermodynamic parameter, when determining the heat balance of a reaction. The specific heats of the different components, before and after the reaction, have to be known in order to define the correct heating of the system.
The heat capacity of crude cement and clinker is measured according to the stepwise method.
An increment of temperature is scanned, and the calorimetric peak, corresponding to the sample heated is integrated, as shown below.

AN190 – Thermal analysis of mineral salts used in the cement industry Private content

Cement is obtained from the baking of mixture of clays and limestones in which silica is one of the main components. Mineral salts are numerous in the initial compound, and sometimes traces of nitrates.
A controlled amount of gypsum can be added to the manufactured cement in order to retard its setting rate.
The thermal behaviour of the three different salts (silica, nitrate, gypsum) is investigated by DSC .

AN187 – Isothermal stability of polybutadiene Private content

Elastomers are often employed in severe conditions of use, particularly of temperature (joints, pipes, ..). Optimal conditions of use must be well defined in order to know when to make replacement. Isothermal thermogravimetry gives information on the resistance of elastomer to a given temperature and determines its decomposition kinetics.
The investigation is run on cis-polybutadiene.

AN186 – Elastomer o-rings stability by TGA

Many elastomers are used as seals, adhesives and flexible parts. Their resistance to heat, solvents and pressure especially make them excellent candidates to manufacture gaskets and o-rings. Three different o-rings are investigated by thermogravimetry with the Labsys TG 1150°C to compare their resistance to temperature: NBR (Nitrile butadiene rubber), EPDM (ethylene propylene diene monomer) and Viton (fluoropolymer).

AN185 – Thermal Stability of various elastomers Private content

Uses of natural rubber are numerous and well known (tires, pipes, shoes, ..). In some cases, synthetic rubbers are prefered due to their specific properties and their lower cost importance. Thermogravimetry allows to compare their resistance to temperature. The investigation is run on the following elastomers : natural rubber, butyl rubber, cis-polybutadien, polychloropren (Neoprene).

AN184 – Polymerization of polyurethan (polyol + polyisocyanate) Private content

Reticulated polyurethan is obtained through the reaction of a glycol and a diisocyanate, according to the following reaction :

X (O = C = N – R – N = C = O) + x (OH – R ‘ – OH) – –> X (O – C = NH .. R – HN – C = O)
Il l
O OR’

The reaction is calorimetrically followed by using the mixing cell with a metallic menbrane (see description in C80 chapter).

AN183 – Heat capacity of elastomers Private content

Elastomers show an important variation of their heat capacity near the glass transition. The knowledge of the heat capacity before and after transition is of a great utility for the uses and applications of the compounds. In DSC methods, heat capacity (Cp) is proportional to thermal power evolved when the sample is heated. Two runs are necessary in order to determine precisely Cp : the first one with empty cells (sample and reference), the second one using the same cells, with the sample. The difference between the two curves characterizes the heat capacity of the sample.

AN181 – Styrene – butadiene (7%) polymerization Private content

The control of polymerization assumes the knowledge of the reaction rates. It is essential to know the quantities of heat which must be removed by the cooling systems to obtain maximum productivity. The isothermal calorimetric test gives the curve for the conversion of monomer into polymer versus time. Its analysis determines the kinetics of polymerization necessary for the previous previsions. An example is given for the polymerization of a mixture of styren and butadien (7%) at different temperatures (130,140,150°C).

AN180 – Glass transition of various synthetic elastomers Private content

Elastomers are frequently used for applications at low temperatures. Their point of brittleness or glass transition must be determined with precision in order to define the minimal temperature of use. The glass transition of an elastomer can be characterized by a variation of heat capacity, which makes thermal analysis a very useful method for detecting this phenomenon.

AN144 – Determination of cristallinity of PET by DSC Private content

PolyEthylene Terephtalate (PET) is a polyester widely employed in daily life (e.g. in water bottles, textile fibers, credit cards). The crystallinity is a very important characteristic because it is directly related to the properties of the polymer (e.g. toughness, clarity, stability). It is defined as the ratio between the crystalline and amorphous phases in the polymer. DSC is one of the main analytical techniques to determine the crystallinity ratio in a semicristalline polymer.

AN143 – Oxidation Induction Time (OIT) of polyethylene by DSC Private content

Oxidation induction time (OIT) is defined as the time that takes oxidation of a sample to occur under oxygen at a given temperature. Applied to polymers, this measurement enables the evaluation of its oxidative stability. As an example, the process of aging of water pipes submitted to chlorinated water could be forecasted by performing OIT analysis. The OIT measurement is defined in the ISO11357-6 standard.

AN142 – Tg of a solution prior to its freeze-drying

Freeze-drying of a solution consists in first cristallyzing it totally, then sublimating the formed ice on installing vacuum. In order to obtain a final product of good quality, it is necessary to install vacuum at a temperature lower than the glass temperature (Tg) of the frozen solution.

AN104 – Thermophysical properties of the composite ceramic-salt system (SiO2/Na2SO4)

A composite ceramic-salt packed bed configuration is being developed for high-temperature thermal storage. The thermophysical properties of the more particular hybrid system SiO2/ Na2SO4 have been investigated in the range from room temperature above the melting point of the salt, 884°C. The Na 2SO4 fraction in the composite materials was varied between 20 and 50 %. The following properties were measured: specific enthalpy, coefficient of thermal expansion and thermal diffusivity.

AN102 – Enthalpies of fusion and heat capacities for ice and tetrahydrofuran hydrate in the range 85 to 270 K

Clathrate hydrates are non-stoichiometric solid compounds in which individual « guest » atoms or molecules of suitable size and shape are held in the cavities provided by the hydrogen-bonded lattice of the « host » water molecules. Recent reports that large reserves of natural gas are present as clathrate hydrates in permafrost regions and beneath the oceans have generated interest in the study of their thermophysical properties such as heat capacity and thermal conductivity. An understanding of such properties will be required regardless of the production scheme used to recover natural gas from these deposits.

AN089 – Heat of mixing of polymer alloys by heat of solution method Private content

Direct measurement of the heat of mixing (interaction) of polymers is not feasible due to their high viscosity. The indirect approach described here is a heat of solution method, in which a
Hess’s Law cycle is used to determine the heat of mixing from the individual heats of solution of the alloy and its constituent polymers in a common solvent.

AN078 – Starch gelatinization in pasta cooking : differential flux calorimetry investigations

Pasta cooking conditions were simulated in a differential flux calorimeter. The profile of the endothermic starch gelatinization peak was observed to directly describe the process
according the first-order kinetics. Isothermal calorimetry provide much more reliable results than do other traditional approaches allowing here assessment of the gelatinization kinetics and simple thermodynamic treatment.

AN024 – Melting and gelation of iota-kappa carrageenan by MicroDSC

Carrageenans are linear sulfated polysaccharides extracted from Red Algae and used in food processing for their gelation properties. Three types of carrageenan exist: iota, kappa and lambda. Gelation is only obtained with the kappa and iota forms. Iota carrageenan produces soft gels whereas the gels obtained with the kappa form are strong. The MicroDSC technique is well adapted to investigate the formation and the melting of such gels