Effects of mixing process on spatial distribution and coexistence of sulfur and zinc in vulcanized EPDM rubber. (18th March 2021)

• Record Type: Journal Article
• Authors: Nakanishi, Yohei; Mita, Kazuki; Yamamoto, Kentaro; Ichino, Kotaro; Takenaka, Mikihito
• Is Part Of: Polymer. Volume 218(2021)
• Publication Date: 2021-03-18
• Subjects: Microscopic X-ray fluorescence -- Rubber -- Chemical mapping; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2021.123486
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Vulcanization of rubber is performed through mechanical mixing of rubber, sulfur, and zinc oxide (ZnO). Sulfur cross-links the rubber by reacting with the double bonds in the rubber, and ZnO is an activator that efficiently accelerates the vulcanization of rubber with sulfur. The extent of coexistence of sulfur and ZnO is an important factor for ensuring effective cross-linking and sufficient dispersion. In this study, we successfully observed the spatial distributions of sulfur and zinc as well as their spatial correlation in vulcanized ethylene–propylene–diene copolymer (EPDM) rubber using microscopic X-ray fluorescence mapping with synchrotron radiation. We found that the mixing processes substantially affects the extent of coexistence of sulfur and ZnO, as well as the spatial distribution of each component. The improved spatial cross-correlation and homogeneity of sulfur and zinc enhances the performance of EPDM rubber. Graphical abstract: Image 1 Highlights: The distribution of sulfur and zinc in vulcanized EPDM rubber was visualized using μ-XRF. The EPDM sample prepared by a two-roll mill had an improved spatial distribution and cross-correlation of sulfur and zinc. The improved spatial cross-correlation and homogeneity of sulfur and zinc enhanced the performance of vulcanized EPDM rubber.