Free volume distribution in monodisperse and polydisperse poly(methyl methacrylate) samples
Free volume distribution in monodisperse and polydisperse poly(methyl methacrylate) samples
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DOI：
10.1021/ma971836y
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发表时间：
1999-01
期刊：
影响因子：
5.5
通讯作者：
K. Süvegh;M. Klapper;A. Domján;S. Mullins;Wiebke Wunderlich;A. Vértes
中科院分区：
文献类型：
--
作者：
K. Süvegh;M. Klapper;A. Domján;S. Mullins;Wiebke Wunderlich;A. Vértes
制备了几种不同分子量和分散度的聚甲基丙烯酸甲酯样品，并用正电子寿命谱对其进行了研究。根据寿命测量，自由体积孔较小，其分布在单分散的PMMA样品比在多分散的样品更窄。另一方面，密度测量显示，在两种样品中的整体自由体积分数是相同的。为了检查这些结果，我们构建了一个模型的聚合物结构和计算的自由体积分布it.Theoretical结果没有显示分散依赖的自由体积分布，这表明，压缩的PMMA颗粒的结构不同于理想的相互作用的自由结构中考虑的计算。后一结果强调了缠结在聚合物结构形成中的作用。
Several poly(methyl methacrylate) samples of different molecular weight and dispersity were prepared and studied by positron lifetime spectroscopy. According to the lifetime measurements, the free volume holes were smaller and their distribution was narrower in monodisperse PMMA samples than in polydisperse samples. On the other hand, density measurements revealed that the overall free volume fractions are identical in both kinds of samples. To check these results, we constructed a model for the polymer structure and calculated free volume distributions in it. Theoretical results have not shown dispersity-dependent free volume distributions which suggested that the structure of compressed PMMA pellets differs from the ideal interaction-free structure considered in calculations. This latter result emphasizes the role of entanglements in the formation of the polymer structure.