Sustainable styrene-butadiene composites with sisal fiber and rubber waste from footwear

Abstract

This study examines the impact of three surface treatment methods on sisal fibers used as reinforcement in styrene-butadiene rubber (SBR) composites: washing with water, alkaline treatment (mercerization), and silanization, with each composite containing 5 wt% of fibers. The preparation process involved using an internal mixer and rubber mixing mill to shape the composites, followed by vulcanization in an automated system press. The effectiveness of the treatments was evaluated using scanning electron microscopy, along with tensile tests, rheometer analysis, and measurements of hardness and density. The treatments enhanced fiber modification by increasing surface roughness through the grafting of silanol groups, thereby improving their interaction with the elastomeric matrix. Notably, composites reinforced with silanized fibers exhibited the highest performance and interaction among the various treatment methods, showing a higher modulus at 100%. Alkaline and silanization treatments reduced vulcanization time. Sisal fibers combined with SBR waste can promote sustainability in the footwear industry.