PVDF-MWNT interactions control process induced beta-lamellar morphology and orientation in the nanocomposites

Mani, Mohan Raj and Gebrekrstos, Amanuel and Madras, Giridhar and Poetschke, Petra and Bose, Suryasarathi (2018) PVDF-MWNT interactions control process induced beta-lamellar morphology and orientation in the nanocomposites. In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 20 (38). pp. 24821-24831.

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Abstract

The effect of methylene blue (MB) modified multiwall carbon nanotubes (MWNTs) on the nucleation and morphology of polyvinylidene fluoride (PVDF) in comparison with the effect of MWNTs was systematically assessed by DSC, C-13 NMR, FT-IR, TEM, WAXS and SAXS analysis. TEM analysis of ultra-microtomed samples revealed that MB modification enhanced the dispersibility of MWNTs in PVDF. Further, the nanocomposites were subjected to mechanical rolling and the synergistic effect of processing and fillers on the PVDF morphology (before and after rolling) at different length scales was studied. Both FT-IR and WAXS analyses suggested that mechanical rolling transforms alpha-PVDF to beta-PVDF (ca. 88%). TEM and two-dimensional WAXS analyses revealed that the MWNTs and beta-crystallites are oriented preferentially along the rolling direction and the degree of orientation is not influenced by the fillers suggesting that crystallite orientation is fully controlled by mechanical rolling. On the other hand, beta-lamellae showed perpendicular orientation with respect to the rolling direction. Unlike beta-crystallites, the beta-lamellar morphology and orientation are highly governed by the fillers as evident from SAXS analysis. Using MWNTs and the MWNT-MB pi-complex, we demonstrate that the beta-lamellar morphology and degree of orientation are controlled by the extent of interaction of fillers with PVDF. Interestingly, both beta-lamellar morphology and degree of orientation correlate well with the mechanical properties of the rolled PVDF. More specifically, the dynamic storage modulus of the samples in the rolling direction increases with increasing beta-lamellar morphology and degree of orientation. The present work demonstrates that the polymer-filler interaction plays a crucial role in regulating the processed polymer morphology and can be tuned by appropriately modifying the surface of fillers through either covalent or non-covalent interactions.

Item Type:	Journal Article
Publication:	PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Publisher:	ROYAL SOC CHEMISTRY
Additional Information:	Copy right for this article belong to ROYAL SOC CHEMISTRY
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	28 Nov 2018 15:13
Last Modified:	28 Nov 2018 15:13
URI:	http://eprints.iisc.ac.in/id/eprint/61185

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