Shear induced crystallization in different polymorphic forms of PVDF induced by surface functionalized MWNTs in PVDF/PMMA blends

Sharma, Maya and Madras, Giridhar and Bose, Suryasarathi (2014) Shear induced crystallization in different polymorphic forms of PVDF induced by surface functionalized MWNTs in PVDF/PMMA blends. In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 16 (31). pp. 16492-16501.

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Abstract

Shear induced crystallization in PVDF/PMMA blends, especially at higher fractions of PMMA, can be quite interesting in understanding the structure-property correlation and processing of these blends. In a recent submission (Phys. Chem. Chem. Phys., 2014, 16, 2693-2704), we clearly demonstrated, using dielectric spectroscopy, that the origin of segmental relaxations concerning the crystalline segments of PVDF in PVDF/PMMA blends in the presence of MWNTs (multiwalled nanotubes) was strongly contingent on the size of the crystallite. We now understand that the fraction of PMMA in the blends governs the origin of polymorphism in PVDF. This motivated us to systematically study the effect of shear on the crystallization behavior of PVDF especially in blends with different polymorphic forms of PVDF. Two model blends were selected; one with a mixture of alpha and beta crystals and the other predominantly rich in alpha crystals. Initially, physical ageing, at different oscillation frequencies (1 rad s(-1) and 0.1 rad s(-1)), was monitored by melt rheology and subsequently, the effect of steady shear was probed in situ without changing the history of the samples. Intriguingly, the rate of crystallization was observed to be significantly higher for higher oscillation frequencies, which essentially suggest that shear has induced crystallization in the blends. More interestingly, the effect of steady shear was more pronounced in the blends rich in alpha crystals (bigger crystallites as observed from SAXS) and at lower oscillation frequencies.

Item Type:	Journal Article
Publication:	PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Publisher:	ROYAL SOC CHEMISTRY
Additional Information:	Copy right for this article belongs to the ROYAL SOC CHEMISTRY, THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy) Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	04 Sep 2014 10:55
Last Modified:	04 Sep 2014 10:55
URI:	http://eprints.iisc.ac.in/id/eprint/49751

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