Influence of Branching Density in Ethylene-Octene Copolymers on Electron Beam CrosslinkabilityReportar como inadecuado




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Department of Polymer Engineering, Faculty of Technology, Tomas Bata University in Zlin, Vavreckova 275, 762 72 Zlin, Czech Republic





Academic Editor: Seth Darling

Abstract Two ethylene-octene copolymers EOC with the same melt flow index MFI = 3 g-10 min but different octene contents, being 20 and 35 wt % EOC-20 and EOC-35, were compared with regard to sensitivity to electron beam crosslinking. Dynamic mechanical analysis DMA revealed a large influence of the octene content on the storage modulus and the glass transition temperature Tg but a smaller influence of irradiation on the properties below melting point Tm. Rheology at 150 °C pointed out large differences in samples crosslinked in the 0–60 kGy range and at lower frequencies 0.1–1 Hz. The loss factor tanδ confirmed that before irradiation the two copolymers were very similar, while after irradiation to 120 kGy, the EOC-35 had considerably lower tanδ than EOC-20, which corresponds to a better elasticity or a higher level of crosslinking. A high-temperature creep test showed a considerably lower creep for EOC with a higher octene content. An analysis of the insoluble gel content exhibited higher values for EOC-35 confirming a higher level of crosslinking. Analysis according to the Charlesby-Pinner equation revealed increased crosslinking-to-scission ratio, GX-GS, for EOC-35. While the GX value changed only slightly, a significant decrease in the GS value was discovered. View Full-Text

Keywords: ethylene-octene copolymer; electron beam irradiation; crosslinking; rheology; creep ethylene-octene copolymer; electron beam irradiation; crosslinking; rheology; creep





Autor: Petr Svoboda

Fuente: http://mdpi.com/



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