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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Semi-interpenetrating polymer networks based on polyurethane and poly(2-hydroxyethyl methacrylate): Dielectric study of relaxation behavior
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Semi-interpenetrating polymer networks based on polyurethane and poly(2-hydroxyethyl methacrylate): Dielectric study of relaxation behavior

机译：基于聚氨酯和聚（甲基丙烯酸2-羟乙酯）的半互穿聚合物网络：弛豫行为的介电研究

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摘要

The study of molecular dynamics by broadband dielectric spectroscopy (BDS) is presented for polyurethane (PU), poly(2-hydroxyethyl methacrylate) (PHEMA) and for semi-IPNs based on PU and PHEMA synthesized by photopolymerization. The dielectric properties were performed in wide range of frequencies and temperatures with the goal to establish the relation between the relaxations and the structure. Five relaxation phenomena were finally detected for PHEMA : gamma-, beta sw-, beta-relaxations at low temperatures and a-relaxation at 150 degrees C at high frequencies plus ionic conductivity relaxation which starts at 0 degrees C. For semi-IPNs the overlapping of gamma- and beta sw-relaxations of PHEMA (-125/-75 degrees C) then with increasing the temperature alpha-relaxation in PU (-75/0 degrees C), next ionic conductivity relaxation which starts at 0 degrees C, and finally the alpha-relaxation of PHEMA (+125/+170 degrees C) were detected. The alpha-relaxation of PHEMA in semi-IPNs shifts to lower temperatures and became broader with increasing amount of PU due to incomplete phase separation in the system and formation of interphases. The dielectric relaxation phenomena were fitted with Havriliak-Negami equation. Activation energy, tau(o) and alpha parameters were calculated. For alpha-relaxations corresponding dielectric characteristics have been determined from Vogel-Fulcher-Tammann equation. The relaxation map for investigated PU, PHEMA and semi-IPNs was built.
机译：提出了利用宽带介电谱（BDS）进行分子动力学研究的方法，用于聚氨酯（PU），聚（甲基丙烯酸2-羟乙酯）（PHEMA）以及基于PU和PHEMA的半IPN（通过光聚合合成）。介电性能是在很宽的频率和温度范围内进行的，目的是建立弛豫与结构之间的关系。最终检测到PHEMA有五种弛豫现象：低温下的伽马，βsw-，β弛豫和高频下在150摄氏度的a弛豫以及从0摄氏度开始的离子电导率弛豫。对于半IPN，重叠PHEMA（-125 / -75摄氏度）的γ-和βsw弛豫，然后随着PU中温度α弛豫（-75/0摄氏度）的增加，下一个从0摄氏度开始的离子电导率弛豫，以及最后检测到PHEMA（+ 125 / + 170摄氏度）的alpha松弛。由于系统中的不完全相分离和中间相的形成，半IPN中PHEMA的α松弛转变为较低的温度，并随着PU含量的增加而变得更宽。介电弛豫现象用Havriliak-Negami方程拟合。计算活化能，tau（o）和α参数。对于α松弛，已经从Vogel-Fulcher-Tammann方程式确定了相应的介电特性。建立了被调查的PU，PHEMA和半IPN的弛豫图。

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