EPR in irradiated Syndiotactic Polystyrene at Elevated Temperatures

• Main Authors: Chien Chen Lee, 李建成
• Other Authors: Sanboh Lee
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/00922928880614788000

碩士 === 國立清華大學 === 材料科學工程學系 === 93 === 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.