English Abstract

Deterioration of Tensile Properties of EPDM by Sodium Chlorite Solution and Chlorine Dioxide Solution

Hitoshi IWABUKI *1
Takuya ISHIDA *1
Satoshi FUKUZAKI *2
*1:Industrial Technology Center of Okayama Prefecture, Kitaku, Okayama, Japan
*2:Graduate School of Bioresources, Mie University, Tsu, Mie, Japan
Nippon Gomu Kyokaishi,(2021),94(11),359-364 Original Paper in Japanese

The changes in tensile properties of black-filled ethylene propylene diene terpolymer (EPDM) in sodium chlorite (NaClO2) solution and chlorine dioxide solution (ClO2) were studied. The diffusion behaviors of Cl and O atoms were investigated by electron probe micro analysis. The deteriorated layer in which Cl and O atoms were diffused was formed on the surface of EPDM immersed in the NaClO2 solution and the ClO2 solution. Dissociated chlorite ion (ClO2-) did not diffuse into EPDM, but ClO2 did and undissociated chlorite acid (HClO2) possibly did. It was suggested that chlorine dioxide diffuses into EPDM faster than hypochlorous acid (NaClO). The tensile properties strongly depended on the depth of diffusion of O (DO) into EPDM, regardless of the type of solution. The hardening of the deteriorated layer enhanced the stress at 100% strain (S100), and the cracks generated in the deteriorated layer resulted in the decrease in the tensile strength (TB) and the elongation at break (EB). The relationship between TB and DO was similar to that between TB and the length of the physical notch given by the razor. The thickness of the degraded layer was found to be equivalent to the physical notch.

Keywords: Degradation, Sodium Chlorite, Chlorine Dioxide, EPDM, Tensile Strength