Study on the effect of wet mixing process on the properties of EPDM rubber/fiber/hollow glass microsphere composite system

Compared to the traditional open mixing process used for the production of the rubber composites, wet mixing process is a lower shear force mixing method. This article revealed the influence of the open mixing process and the wet mixing process on the microstructure, density, mechanical properties, and ablation performance of ethylene propylene diene monomer (EPDM) rubber/fiber/hollow glass microsphere composite system. The results showed that the wet mixing process increased the fiber length by more than 300% compared to the open mixing process, while the fragmentation rate of the hollow glass beads was reduced by 94.4%, these effectively maintained the structural integrity of the fibers and the hollow glass microsphere filler. By using the wet mixing process, the density of EPDM composite materials can be reduced by about 20%, and the tensile strength and ablation resistance of these composites were also significantly improved. Compared to polyimide fiber and aramid fiber short fibers, the wet mixing process of solution-based rubber had a more significant effect on improving the length and ablation resistance of phenolic fiber and carbon fiber fibers which having poor shear strength.