Cooperativity Scaling and Free Volume in Plasticized Polylactide
Cooperativity Scaling and Free Volume in Plasticized Polylactide
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DOI：
10.1021/acs.macromol.9b00464
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发表时间：
2019-08-27
期刊：
影响因子：
5.5
通讯作者：
Dargent, Eric
中科院分区：
文献类型：
--
作者：
Araujo, Steven;Delpouve, Nicolas;Dargent, Eric
通过量热、介电和正电子湮没寿命测量的组合，获得了与自由体积变化的超Arrhenius行为相关的活化能增加的实验证据。聚丙交酯中自由体积的量由组合物中乙酰柠檬酸三丁酯增塑剂的量控制。增塑被证明可以降低玻璃化转变时的脆性指数和合作运动的规模。通过对动力学脆性的体积分量和能量分量的计算，发现脆性的下降与协同重排区的大小有关。其结果是，直接的相关性已建立在整个增塑聚乳酸系列的协同性和活化能之间。协同性随温度和增塑剂含量的变化可以简化为一条具有自由体积的主曲线。
The experimental evidence of the increase of activation energy associated with the super Arrhenius behavior governing amorphous polylactide by free volume variations has been obtained through a combination of calorimetric, dielectric, and positron annihilation lifetime measurements. The amount of free volume in polylactide was controlled by the amount of acetyltributylcitrate plasticizer in the composition. Plasticization is shown to decrease both the fragility index and the scale of cooperative motions at the glass transition. The calculations of volume and energetic components of kinetic fragility reveal that the fragility drop is governed by the change in the size of cooperative rearranging region. As a result, direct correlation has been established between cooperativity and activation energy for the entire plasticized polylactide series. It is also shown that cooperativity variations with both temperature and plasticizer content can be simplified as a master curve with free volume.