高分子材料在照設過加瑪射線後經常會產生自由，本文探討對排聚苯乙烯在經過鈷六十加碼射線照射後所產生的自由機種類與其在高溫下衰減的動力學過程。

When the polymer materials are exposed under gamma-ray, it generates some free radicals. After Co60 gamma-ray irradiation, the radical number will decrease as time goes by. Even at the room temperature it also decays slowly. We irradiated the syndiotactic polystyrene(sPS) samples by Co60 gamma-ray and calculated the radical number by analyzing its electron paramagnetic resonance(EPR) spectra. We also simulate two kinds of free radicals in sPS, which are disubstituted benzyl radical -(CH2)-C(C5H5)•-(CH2)- as Radical type A (Ra) and cyclohexadienyl radical -(CH2)-CH(C5H6•)-(CH2)- as Radical type B (Rb). Using software WINEPR, SimFornia and WinSim to analyze all spectra, we calculate the number of each radical type. Furthermore, we analyzed its rate constant isothermally at several different temperatures. We found Ra decays faster than Rb, and the mechanism of the radical number decay follows a first-order kinetic process. The activation energy of decay reaction is also obtained.

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