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Critical Insights into the Effect of Shear, Shear History, and the Concentration of a Diluent on the Polymorphism in Poly(vinylidene fluoride)

Gebrekrstos, Arnanuel and Sharma, Maya and Madras, Giridhar and Bose, Suryasarathi (2017) Critical Insights into the Effect of Shear, Shear History, and the Concentration of a Diluent on the Polymorphism in Poly(vinylidene fluoride). In: CRYSTAL GROWTH & DESIGN, 17 (4). pp. 1957-1965.

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Official URL: http://dx.doi.org/10.1021/acs.cgd.6b01896

Abstract

The effect of shear, shear history, and addition of poly(methyl methacrylate) (PMMA) in inducing the,beta-polymorph in poly(vinylidene fluoride) (PVDF) was investigated systematically for melt-mixed PVDF/PMMA blends. Various techniques-shch as polarized optical microscopy, (P0M) coupled' to a hot stage and a shear cell, Fourier transforrn, `infrared spectroscopy (PTIR), differential thermal analysis, melt-theology, and dielectric relaxation spectroscopy were used to gain a mechanistic insight for the observed polymorphism in PVDF. Different PVDF tieli blends were prepared by melt-mixing and were subjected to different shear histories on a rheonieter, and the induction time was monitored with respect to PMMA content and,the applied shear flow in the blends. The rheological measurements= revealed that the induction time was `significantly lower for blends with a higher PVDF content (>= 80 wt %), which was ascribed to the diluent effect of PMMA that restricts, the, chain mobility of PVDF and a Ionger,time is required to start the crystallization process. The crystalline, morphology observed from POM demonstrates that the growth rate of spherulites was greatly reduced with increasing PMMAI content in the blends., FTIR results were used to determine the amount of beta phase in the blends before and after the shear history. The blends'tliat were sheared at high temperature (220 degrees C) showed more beta phase than the blends that were sheared. around the crystallization temperature. This study clearly demonstrates the fact that shear, shear history, and the content of PMMA significantly influence the conformational change that results in phase transformation in PVDF. Further, this study will help guide researchers working on various aspects of polymer processing where-the, effect of blending and shear on polymorphism is very important.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre: Division of Mechanical Sciences > Chemical Engineering
Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Division of Interdisciplinary Research > Centre for Nano Science and Engineering
Depositing User: Id for Latest eprints
Date Deposited: 20 May 2017 06:59
Last Modified: 20 May 2017 06:59
URI: http://eprints.iisc.ac.in/id/eprint/56954

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