Characterization and mechanism of natural rubber composites reinforced by modified calcium sulfate whisker

Abstract This study concentrated on the mechanical properties of natural rubber (NR) composites [modified calcium sulfate whisker (MCSW)] and the reinforcement mechanism of MCSW on NR. First, anhydrous CSW with an orthogonal crystal system bottom center structure was prepared by hydrothermal method. Subsequently, MCSW was obtained by treating whiskers with inorganic, organic compounds, which effectively coated the surface of the whiskers with an average thickness of 40.85 nm, making the surface change from hydrophilic to hydrophobic. The CSW/MCSW filler was added to the NR under the optimum experimental conditions of 70°C, 12 min, 5 times of rolling, 140°C, and 1 h of curing time. The results showed that the tensile strength, elongation at break, and crosslink density of the NR composites with 15 phr of MCSW added were increased by 80.8%, 9.0%, and 80.2%, respectively, compared with the NR without the filler. The mechanism of MCSW improving the performance of composites was revealed from vulcanization kinetics and interfacial thermodynamics. In this work, a new type of high‐efficiency environmental protection NR filler reinforcing agent was developed.