Thermal Degradation of Polymers at High Temperatures

Work on thermal ~egradation of poly mers has prev iously been carried out aL lempC'mt ures up to about 500 G. In the present work the range has been extend cd to 850 0 C. Polystyrene was pyrolyzed in a vacuum and also in helium at atmos pheric pressure at 3620 and at 850 0 C. Analysis of t he volatile products indicates that higher temperatures a nd hi~her. pressures cause a greater fragmen tation of the volatile prod ucts. Samples of poly (vmyh dene fl uoride), polyaery IOl1ltnle, a nd polytn vlllylbenzene, were pyrolyzed in a vaeu um at temperatures from 3500 to 800 0 C. Thc more volat il e products were analyzed qua li tat ively and qLl[),ntita,t ively in a mass s pectrometer. T he less volatile products were tested fo r t heir average molec ular weight by a microcryoscopic method . R ates of thermal degradat i:> n were als') determined for t he last t hree poly mers. The activation energ ies in the temperature range 218 0 to 440 0 C lVere found to be 48 31 an d 73 kcal/ mole, respect ively, for poly(v inyl idenc fluor ide), polyacry lo ni t rile, a nd polytr ivin y lbcnllene.