Oil absorbents based on styrene-butadiene rubber

Abstract

Four oil absorbents based on styrene–butadiene (SBR)—pure SBR (PS), 4-tert-butylstyrene–SBR (PBS), EPDM–SBR network (PES), and 4-tert-butylstyrene-EPDM-SBR (PBES)—were produced from crosslinking polymerization of uncured styrene–butadiene rubber (SBR), 4-tert-butylstyrene (tBS), and ethylene–propylene–diene terpolymer (EPDM). The reaction took place in toluene using benzoyl peroxide (BPO) as an initiator. Uncured SBR was used as both a prepolymer and a crosslink agent in this work, and the crosslinked polymer was identified by IR spectroscopy. The oil absorbency of the crosslinked polymer was evaluated with ASTM method F726-81. The order of maximum oil absorbency was PBES > PBS > PES > PS. The maximum values of oil absorbency of PBES and PBS were 74.0 and 69.5 g/g, respectively. Gel fractions and swelling kinetic constants, however, had opposite sequences. The swelling kinetic constant of PS evaluated by an experimental equation was 49.97 × 10−2 h−1. The gel strength parameter, S, the relaxation exponent, n, and the fractal dimension, df, of the crosslinked polymer at the pseudo-critical gel state were determined from oscillatory shear measurements by a dynamic rheometer. The morphologies and light resistance properties of the crosslinked polymers were observed, respectively, with a scanning electron microscope (SEM) and a color difference meter.