Properties of Natural Rubber Vulcanizates/Nanosilica Composites Prepared Based on the Method of In-situ Generation and Coagulation

摘要

Using the characteristics of silica sol dispersing well in water and easyformation of silica gel when the silica sol is heated, by mixing a system of concentrated natural rubber latex and silica sol, the silica sol can in-situ generate SiO_2 particles when heated. After coagulation of the mixed system, natural rubberanosilica composites C(NRSiO_2) were obtained. The composites C(NRSiO_2) and their vulcanizates were studied using a rubber processing analyzer (RPA), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The influence of silica conten ts on the C(NRSiO_2) vulcanizates mechanical properties, cross-linking degree, Payne effect, dissipation factor (tanδ), and the particle size and dispersion of SiO_2 in NR were investigated. The results obtained were compared with the NR/SiO_2 composites based on traditional dry mixing of bale natural rubber and precipitated silica (white carbon black). The results showed that when using a sulfur curing system with a silica coupling agent (Si69) in C(NRSiO_2), the vulcanizate had better mechanical properties, higher wet resistance, and lower rolling resistance than those without Si69. In the composites C(NRSiO_2) and their vulcanizates, the SiO_2 particles' average grain diameter was 60nm, and the good-dispersion of the in-situ generated SiO_2 in the rubber matrix were a significant contribution to the satisfactory properties of C(NRSiO_2) composites and their vulcanizates.