Correlation between Gas Diffusion Coefficient and Positron Annihilation Lifetime in Polymers with Rigid Polymer Chains
Correlation between Gas Diffusion Coefficient and Positron Annihilation Lifetime in Polymers with Rigid Polymer Chains
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DOI：
10.1021/ma992051q
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发表时间：
2000-07
期刊：
影响因子：
5.5
通讯作者：
Kazuhiro Tanaka;Toshinao Kawai;H. Kita;K. Okamoto;Y. Ito
中科院分区：
文献类型：
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作者：
Kazuhiro Tanaka;Toshinao Kawai;H. Kita;K. Okamoto;Y. Ito
在308 ~ 473 K温度范围内，测定了聚酰亚胺、聚苯并恶唑和高玻璃化转变温度（Tg）高于488 K的聚（2，6-二甲基-1，4-苯醚）（PPO）的CO2和CH 4扩散系数D和正电子偶素（o-Ps）寿命τ3。这些聚合物在308 K下的log（D/T）和τ3曲线低于在Tg − 90 K至Tg + 70 K温度下对具有相对低Tg的聚合物观察到的相关线，并由扩散的自由体积理论解释。这些高Tg聚合物的较低D值归因于其聚合物链的受限局部运动。随着温度的升高，PPO和聚酰亚胺的曲线变得接近相关线。
Diffusion coefficients D of CO2 and CH4 and lifetimes of orthopositronium (o-Ps) τ3 were measured at temperatures from 308 to 473 K for polyimides, a polybenzoxazole, and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with high glass transition temperatures Tg's above 488 K. The plots of log(D/T) and τ3 for these polymers at 308 K were below the correlation line observed for polymers with relatively low Tg's at temperatures from Tg − 90 K to Tg + 70 K and interpreted by the free volume theory for diffusion. The lower D values for these high-Tg polymers were attributed to the restricted local motion of their polymer chains. With increasing temperature, the plots for PPO and a polyimide became close to the correlation line.