One interesting feature of LABSYS evo STA is the possibility to connect its gas exhaust to a FTIR spectrometer in order to identify the vapours evolving from the sample and to monitor the level of each identified vapour.
The following experimental procedure has to be used:
Sample : Polyoxymethylene
Crucible : Platinum
Atmosphere : Argon 60ml/min
Experimental procedure : The temperature is programmed from ambient up to 600°C at 10 °C/min.
Results and conclusions
The Heat Flow curve presents two endothermic effects. The low temperature peak (with a maximum at 187.2°C) may correspond to melting because it isn’t related to any mass loss signal. While the higher temperature peak (with two maxima at 355.3°C and 378.9°C) corresponds to the decomposition of Polyoxymethylene and is related to the main mass loss of 98.82%.. Finally, the last mass loss of 1.18% is due to a second decomposition.
From the FTIR spectra it is possible to draw the variation of intensity associated to the specific absorption band for carbon monoxide (2000-2200cm-1), formaldehyde (2600-3100cm-1) which are decomposition products of POM and tetrafluoroethylene (1100-1400cm-1). The release of this last compound is probably not linked with the degradation of the macromolecular chain, but with the presence of an additive or a residue of the preparation of the polymer in the final material.