Melting and degradation behaviour of needle‐like poly(oxymethylene) crystals

DSC/TG (differential scanning calorimetry/thermal gravimetry) simultaneous measurements have been carried out for needle‐like and other poly(oxymethylene) crystals and the occurrence of degradation, overlapping the melting, has been confirmed for needle‐like and fibrous extended‐chain crystals. A theory to analyze the DSC curves with reference to the corresponding TG has been formulated and the contributions from the melt and the degradation have been resolved by means of computer curve‐fitting. For needle‐like crystals, the heat of fusion, 2260 cal/mol (9450 J/mol) and the melting point, 183–184°C (as well as the heat of degradation, 13,17 kcal/mol [55,05kJ/mol]) have been obtained and discussed with reference to the data from other samples. Systematic experiments for the effect of running conditions on the shape of DSC curves have been made and described in the Appendix.