Aging bulk modulus obtained from enthalpy and volume relaxations of a-PMMA and its blends with PEO
Aging bulk modulus obtained from enthalpy and volume relaxations of a-PMMA and its blends with PEO
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从 a-PMMA 及其与 PEO 共混物的焓和体积弛豫获得的老化体积模量
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
I. Emri
中科院分区：
文献类型：
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作者：
P. Slobodian;J. Vernel;Vladimir Pelı́šek;P. Sáha;P. Říha;R. Rychwalski;J. Kubát;I. Emri
利用测定的无规聚甲基丙烯酸甲酯及其与环氧乙烷共混物的热焓和体积松弛数据，计算了老化体积弹性系数Ka，暂定为导数(∂h∂v)T。Ka值主要低于活塞式PVT装置直接测定的相应体积模量数据。然而，总的来说，可以认为Ka值接近在液体状态下测得的模数。在非晶态硒上测量的KA数据支持了这一观点，非晶态硒在液体状态下的可压缩性明显低于常见的非晶态聚合物。用单个内变量讨论了不可逆过程的热力学结果，但没有得到合适的焓/体积导数的表达式。
Enthalpy and volume relaxation data measured on atactic poly(methyl methacrylate) and its blends with poly(ethylene oxide) are used to calculate an aging bulk modulus, Ka, tentatively defined as the derivative (∂ h∂ v)T . The Ka values are mainly lower than the corresponding bulk modulus data determined directly with a piston-type PVT-device. On the whole, however, the Ka values can be considered as lying close to the moduli measured in the liquid state. This notion is supported by Ka data measured on amorphous selenium, which has a significantly lower compressibility in the liquid state than common amorphous polymers. The results are discussed in terms of thermodynamics of irreversible processes using a single internal variable, yet without arriving at suitable expression for the enthalpy/volume derivative.