In this paper the changes in the thermal and mechanical properties of unplasticized polyvinyl chloride (UPVC) films
under ion beams irradiation have been studied. Two series of irradiation were performed; one series irradiated with a
constant fluence ð2:25 109 ions=cm2Þ but at different beam energies (25–37 MeV) and another series irradiated at a
constant energy (25 MeV) over a wide range of fluence ð109–1015 ions=cm2Þ. The thermogravimetric analysis (TGA)
thermograms showed that the thermal decomposition of UPVC films either before or after ion beams irradiation occurred
through two stages. The films were very stable up to 500 K,the major weight loss occurred during the temperature
range (500–630 K) and a second stage up to 750 K in which the films showed a stability somewhat against
thermal decomposition. However,both the irradiated series showed a relatively higher thermal stability than the
unirradiated one as indicated from the decomposition temperature at a certain % weight loss. The determination of
the kinetic parameters indicates that the thermal decomposition reaction follows zero order reaction with activation
energies dependent on the heating temperature and not on the residual mass. For the 25 MeV Hþ irradiated series,the
average activation energy was found to increase from 249 kJ/mol for unirradiated UPVC to 306 kJ/mol for the irradiated
films at a fluence of 2:25 109 ions=cm2. Then,the change in activation energy values for both series was found
to occur in a similar trend. In addition,the high energy irradiation process in our energy range of study has no clear
effect on the mechanical properties of films. Meanwhile,for the dosed samples,the elongation percent and the yielding
point were affected significantly. 2002 Elsevier Science B.V. All rights reserved.