Caracterização de compósitos elastoméricos com resíduos industriais de copolímero de butadienoe estireno (SBR) desvulcanizado por micro-ondas

Abstract

The aim of this work was to evaluate the effects of two accelerated aging processes on the chemical characteristics of styrene butadiene rubber (SBR) composites filled with industrial scraps (SBR-r) devulcanized by microwave. The SBR-r was ground under ambient conditions and subjected to microwave exposure for 1, 2 and 3 min. The mixtures were developed by the incorporation of the devulcanized SBR-r into the rubber matrix and subsequent revulcanization. The compositions ware submitted to two types of accelerated aging processes, in an air oven (for 7 and 14 days) and in an artificial weathering test (UV chamber for 240 and 480 h). The mechanical properties (tensile and tear strength, compression set, abrasion loss, and resilience) indicated that the better performance was achieved by the composition containing 80 phr of SBR-r devulcanized for 2 min in the microwave. The changes in the chemical characteristics were evaluated through crosslink density and ATR-FTIR analysis. The results were compared to a control sample (with 0 phr of SBR-r) submitted to the same conditions. The results revealed that the aging mechanism was dependent on the presence of SBR-r and on the time of aging. Crosslink density analysis confirmed the occurrence of crosslink scission at lower times and formation of additional crosslinking in a post cure process at longer times of aging. ATR-FTIR results indicated an oxidative process in the surface of the composites for both aging processes. Moreover, artificial weathering promoted a more pronounced change in the chemical structure of the compounds.