Effect of crosslink on the characteristic length of glass transition of network polymers
Effect of crosslink on the characteristic length of glass transition of network polymers
复制标题
DOI：
10.1002/polb.20852
复制
发表时间：
2006-07
期刊：
影响因子：
--
通讯作者：
Takashi Sasaki;T. Uchida;K. Sakurai
中科院分区：
文献类型：
--
作者：
Takashi Sasaki;T. Uchida;K. Sakurai
用差示扫描量热法测定了交联体聚苯乙烯和聚甲基丙烯酸甲酯的玻璃化转变温度的特征长度。特征长度随交联程度的增加而减小，该特征长度对应于聚合物节段弛豫引起的协同重排的长度尺度。基于立方晶格上的简单聚合物网络模型，计算了交联聚合物构型熵的相对值。结果表明，最小协同重排区域的构型熵随着交联程度的增加而减小，这是特征长度的上述行为的原因。发现交联对聚甲基丙烯酸甲酯的特征长度和玻璃化转变温度的影响大于交联聚苯乙烯，这反映了交联段结构的差异。
The characteristic length of the glass transition temperature was evaluated for crosslinked bulk polystyrenes and poly(methyl methacrylate)s by differential scanning calorimetry. The characteristic length, which corresponds to a length scale of the cooperative rearrangement due to polymer segmental relaxation, was revealed to decrease with increase in the degree of crosslink. The relative values of configurational entropy for crosslinked polymers were evaluated based on a simple polymer network model on a cubic lattice. As a result, the configurational entropy of the smallest cooperatively rearranging region was revealed to decrease with increase in the degree of crosslink, which is responsible for the above behavior of the characteristic length. The effects of crosslink on the characteristic length and the glass transition temperature were found to be stronger for crosslinked poly(methyl methacrylate)s than for crosslinked polystyrenes, which reflects the difference in the structure of crosslink segment.