Some of the figures and tables which appear in this book have previously been published elsewhere and we wish to express our thanks to the following for granting us permission to reproduce the material listed in this work.

SynopsisThe thermal and oxidative degradation of poly( phenylene sulfide) and perfluoropoly-(phenylene sulfide) have been studied by a weight-loss method. The products of breakdown in vacuum have also been analyzed. The poly(pheny1ene sulfide) is more thermally stable in inert and oxidizing atmospheres than the fully fluorinated analog. The breakdown products can be accounted for by chain scission and transfer reactions. The formation of a large proportion of residue implies that crosslinking reactions play an important part in the degradation.

A study of the ratio of the glass temperature to the melting point of 132 polymers is described. Contrary to some other workers' observations on smaller numbers of polymers there is no sharp division between the ratios observed for symmetrical and unsymmetrical polymers. The arithmetic mean of the ratio is 0·63 and 0·69 respectively, but the combined standard deviation is 0·11. There is no correlation between the ratios and the crystalline forms of polymers.

Three poly(arylene sulphones) have been studied by thermogravimetry to ascertain their relative thermal stabilities in both inert and oxidising atmospheres. Experiments have been carried out at a rate of temperature rise of 2°C min−1 and isothermally at a number of temperatures. The level of stability found compared favourably with that of other heat‐resistant materials, for example the addition type polyimides. The polymers have also been examined by pyrolysis gas chromatography mass spectrometry using two different procedures. In the first, fresh samples were pyrolysed at a number of increasing temperatures, whereas in the second, the sample was subjected to successive pyrolyses at the same temperature intervals.

synopsisA number of perfluoro polymers were heated a t a constant rate of temperature rise in an atmosphere of nitrogen or air, and the volatile degradation products were passed into an aqueous solution, where the F-ions produced were monitored with a fluoride ion-selective electrode. Compounds giving rise to F-ions were formed in both nitrogen and air, but in larger amounts in the latter atmosphere. For the formation of appreciable quantities of F-ions, temperatures greater than 5OOOC were normally necessary.