Fine Structures in Phase-Separated Domains of a Polyolefin Blend via Spinodal Decomposition
Fine Structures in Phase-Separated Domains of a Polyolefin Blend via Spinodal Decomposition
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DOI：
10.1021/ma061064i
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发表时间：
2006-09
期刊：
影响因子：
5.5
通讯作者：
Xiaohua Zhang;Zhigang Wang;C. Han
中科院分区：
文献类型：
--
作者：
Xiaohua Zhang;Zhigang Wang;C. Han
聚乙烯（PE）是最常用和常见的聚合物材料之一。为了改善其性能，它通常与其他聚合物共混，如无规烯烃共聚物的弹性体。了解混合这些聚合物的基本物理原理非常重要，以便通过特定的配料和制造工艺控制最终性能。在线性低密度聚乙烯（LLDPE）共混物的情况下，混合物可以经历液-液相分离（LLPS）和结晶。这些工艺对最终产品的形态和性能影响很大。在聚烯烃共混物中，相分离现象1 -4和结晶动力学5，6已被广泛研究。然而，只有有限的研究已报告的同时相分离和结晶过程。7-14高分子共混物的旋节线分解（SD）和图案形成的动力学一直是理论和实验研究的主题，并提供了非线性非平衡现象的迷人例子。15-17在过去的二十年中，已经进行了许多研究，通过使用光散射18 -20和中子散射21 -23测量的SD来调查浓度波动的增长。SD过程的特征形态，双连续和相互连接的管状结构，以及它的生长已经得到了很好的研究和理解，至少从全局和统计的角度来看。通过双猝灭实验24 -27或其他技术，28-30可以研究相分离畴内的点状小物体。另一方面，在“后期”SD过程和结晶的精细结构仍然在很大程度上未被探索。因此，本文通过双温淬火引入两步相分离，以获得相分离畴内的结晶精细结构。在SD过程的“后期阶段”，双连续结构可能破裂并生长成更大的物体，31并且随后的结晶或相分离/结晶过程可以产生具有基本和应用重要性和兴趣的独特形态。在本报告中，我们研究了“后期”SD过程中的精细结构。我们研究了精细结构的形成机制，并确定了通过多步相分离/结晶过程形成的观察到的形态。
Polyethylene (PE) is one of the mostly used and common polymeric materials. To improve its properties, it is often blended with other polymers, such as elastomers of random olefin copolymers. It is very important to understand the fundamental physics of mixing these polymers in order to control the final properties through the specific compounding and manufacturing processes. In the case of linear low-density polyethylene (LLDPE) blends, the mixtures can undergo both liquid-liquid phase separation (LLPS) and crystallization. These processes affect greatly the morphology and properties of the final products. Both phase separation phenomena1-4 and crystallization kinetics5, 6 have been studied extensively in polyolefin blends. However, only limited studies have been reported on the simultaneous phase separation and crystallization processes. 7-14 The dynamics of spinodal decomposition (SD) and the pattern formation of polymer blends have been the subjects of both theoretical and experimental investigations and provide fascinating examples of nonlinear nonequilibrium phenomena. 15-17 Over the past two decades, many studies have been made to investigate the growth of concentration fluctuations via SD employing light scattering18-20 and neutron scattering21-23 measurements. The characteristic morphology of the SD process, bicontinuous and interconnected tubelike structure, and its growth have been well studied and are reasonably well understood, at least from a global and statistical point of view. By the double-quench experiment24-27 or other techniques, 28-30 the dotlike small objects inside phase-separated domains can be studied. On the other hand, the fine structures in the “late-stage” SD process and crystallization remain largely unexplored. Thus, two-step phase separation was here introduced by double temperature quench to obtain the crystallized fine structures inside phase-separated domains. In the “late stage” of the SD process, the bicontinuous structures may break up and grow into larger objects, 31 and subsequent crystallization or phase separation/crystallization process could generate a unique morphology with both fundamental and applicational importance and interest. In the present report we studied the fine structures in the “late-stage” SD process. We investigated the mechanism of the formation of the fine structures and identified the observed morphologies formed through a multistep phase separation/crystallization process.