English Abstract

Quantitative Analysis for Estimating the Content Ratio of Ethylene Vinyl Acetate Copolymer (EVA)/ Very Low Density Polyethylene (V-LDPE) Blended Foam

Kenichi HARANO *1
Tsuyoshi NISHIWAKI *2
*1:Asics Corp., Nishi-ku, Kobe, Hyogo, Japan
*2:Asics Corp., Chuo-ku, Kobe, Hyogo, Japan
Nippon Gomu Kyokaishi,(2019),92(10),363-369 Original Paper in Japanese

Recently, ethylene vinyl acetate (EVA) and very low density polyethylene (V-LDPE) blended foam (EVA/V-LDPEfoam) used in various industrial fields has been studied in order to improve the mechanical properties such as lightness and cushioning. The content ratio of EVA and V-LDPE was one of the important factors to control mechanical properties. The determination of the ratio of the above was desired from the view of quality control. The ratio could be determined through comparison between the content of vinyl acetate of non-linked EVA(VA wt%N) and EVA/polyethylene (PE) foam (VA wt%F). However, it was difficult to determine VA wt%N by the conventional analytical techniques. In this study, a trace amount of non-cross-linked EVA in the cross-linked foam is focused on the determination of VA wt%N. Separation of non-linked EVA was attempted by using solubility-difference between EVA and V-LDPE which were extracted from the foam to 10 vol% acetonitrile in chloroform solution. As a result, non-linked EVA was separated from non-linked components including a trace amount of V-LDPE by elution-time-difference. VA wt%N was estimated by Fourier-transform infrared spectroscopy (FT-IR) and the content ratio was determined through comparison between VA wt%N and VA wt%F.

Keywords: Ethylene Vinyl Acetate, Very Low Density Polyethylene, Cross-link, Foam, High Performance Liquid Chromatography, FT-IR, Non-cross-linked Component, Solubility-difference, Elution-time-difference