Pressure and cooling rate‐induced densification of atactic polystyrene
Pressure and cooling rate‐induced densification of atactic polystyrene
复制标题
压力和冷却速率诱导的无规聚苯乙烯致密化
DOI：
--
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
R. Pantani
中科院分区：
文献类型：
--
作者：
R. Pantani
从工业的角度来看，对后处理聚合物比容的确切了解通常是一个具有巨大战略重要性的因素。这个问题是复杂的，因为在恒定的温度和压力下，固体聚合物的比容不仅是当前温度和压力的函数，而且还是熔体的整个形成历史的结果。在这项工作中，在不同条件下固化的样品的特定体积进行了分析，并与它们的形成历史。研究了宽范围的冷却速率（从5 × 10−3到300 K/s）和凝固压力（从0.1到80 MPa）。结果表明，冷却速率和凝固压力的协同效应：较低的冷却速率导致更高的压力诱导致密化相对于较高的冷却速率。一个简单的唯象模型，它基本上连接的致密化效果的玻璃化转变温度的依赖性上的冷却速率和凝固压力被采用来描述的实验数据。从致密化效应出发，研究了压力和冷却速率对玻璃化转变温度的影响。在此基础上，得到了玻璃化转变区体积弛豫时间与温度和压力的关系。© 2003 Wiley Periodicals，Inc.应用聚合物科学杂志89：184-190，2003
The exact knowledge of postprocessing polymer-specific volume is often a factor of enormous strategic importance from an industrial point of view. The subject is complicated by the fact that the specific volume of solid polymers at a constant temperature and pressure is not only a function of the current temperature and pressure, but is also a consequence of the whole formation history from the melt. In this work, specific volumes of samples solidified in different conditions are analyzed and related to their formation history. A wide range of cooling rates (from 5 × 10−3 to 300 K/s) and solidification pressures (from 0.1 to 80 MPa) are examined. The results show a synergic effect of the cooling rate and solidification pressure: Lower cooling rates result in a much higher pressure-induced densification with respect to higher cooling rates. A simple phenomenological model which essentially links the densification effect to the dependence of the glass transition temperature upon the cooling rate and solidification pressure is adopted to describe the experimental data. Starting from the densification effect, the effect of the pressure and cooling rate on the glass transition temperature is evaluated. Furthermore, some conclusions about the dependence of the volume relaxation time on the temperature and pressure in the glass transition range are achieved. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 184–190, 2003