Journal
POLYMER
Volume 114, Issue -, Pages 44-53Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.polymer.2017.02.076
Keywords
Ethylene-alpha-octene copolymers; Interphase; MWCNTs; Dispersion; Solid-state NMR
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Funding
- National Natural Science Foundation of China (NNSFC) [51422305]
- China Postdoctoral Science Foundation [2016M601249]
- Innovation Team Program of Science & Technology Department of Sichuan Province [2014TD0002]
- Sichuan Provincial Science Fund for Distinguished Young Scholars [2015JQO003]
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Two kinds of ethylene-alpha-octene copolymers (ethylene-alpha-octene block copolymer, OBC, and ethylene-aoctene random copolymer, ORC) and their composites with MWCNTs were investigated by means of various solid-state NMR techniques. C-13 MAS NMR revealed that there were only orthorhombic crystals in OBC composites, which resulted in stronger volume exclusion effect towards MWCNTs than that in ORC composites. The degree of microphase separation is quite different for the OBC and ORC composites as revealed by 2D WISE NMR experiment, which also indicated that MWCNTs selectively localize in the immobilized interphase between crystalline and amorphous mobile phases, acting as a compatibilizer in OBC-based materials. Based on the spin diffusion results, the thicknesses of the interphases were estimated to be 10.4 nm for OBC and 5.4 nm for ORC respectively. It is also found out that the interphase thickness and the dimension size of MWCNTs were at the same nanoscale for OBC. Consequently, compared with ORC composites, a uniform dispersion of MWCNTs can be achieved just by utilizing OBC copolymer with blocky architecture and larger interphase thickness, and then much lower conductivity percolation threshold can be obtained in OBC composites. (C) 2017 Elsevier Ltd. All rights reserved.
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