A Criterion for Flow-Induced Oriented Crystals in Isotactic Polypropylene under Pressure
A Criterion for Flow-Induced Oriented Crystals in Isotactic Polypropylene under Pressure
复制标题
压力下等规聚丙烯中流动诱导取向晶体的判据
DOI：
10.1002/marc.201700407
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发表时间：
2017
影响因子：
4.6
通讯作者：
Li Zhong Ming
中科院分区：
文献类型：
--
作者：
Yang Shu Gui;Ma Zhe;Lei Jun;Li Liangbin;Hsiao Benjamin S;Li Zhong Ming
流动诱导取向晶体由于能显著提高聚合物产品的刚度和强度而引起了人们的广泛关注。当然，了解定向晶体形成的必要条件对工业和聚合物物理学都很重要。根据Mykhaylyk及其同事提出的流动比功概念，仔细总结了流动比功w（T，P）的表达式，并验证了当w（T，P）高于临界流动比功wc(T，P)=（1.7±0.7）× 107J m−3时，在压力（50、100和150 MPa）和过冷65 K下流动可以诱导等规聚丙烯中的取向晶体。压力对wc（T，P）的影响来自两个方面：一是对熔体粘度的影响（Barus定律），二是对平衡熔化温度的影响（Clapeyron方程）。本研究可以指导实际加工制造具有取向晶体的高性能聚合物产品。
Flow‐induced oriented crystals have attracted considerable attention because they significantly increase stiffness and strength of polymer products. Naturally, understanding the necessary condition of forming oriented crystals is of importance for both industry and polymer physics. Following the concept of specific work of flow proposed by Mykhaylyk and co‐workers, the expression of the specific work of flow,w(T,P), was carefully summarized and verified that whenw(T,P)is above a critical specific work of flow,wc(T,P)= (1.7 ± 0.7) × 107J m−3, oriented crystals in isotactic polypropylene can be induced by flow at pressures (50, 100, and 150 MPa) and at a undercooling of 65 K. The influences of pressure onwc(T,P)stem from two facets: one is the influence on the melt viscosity (the Barus law), and the other one is the influence on the equilibrium melting temperature (the Clapeyron equation). The current study can guide real processing to fabricate high‐performance polymer products with oriented crystals.