Abstract
Peroxide cross-linked silica filled natural rubber composite was prepared from a commercial natural rubber (NR) latex containing ammonia and silica generated in situ by using a sol-gel reaction of tetraethoxysilane (TEOS). The silica content was ten parts per one hundreds rubber by weight. Morphology of the in situ silica in the soft composite, which was observed by transmission electron microscopy, showed that the in situ silica was formed into aggregates in a few hundreds nanometer level. Reinforcement effects of the in situ silica and strain-induced crystallization (SIC) were investigated by simultaneous time-resolved wide-angle X-ray diffraction and tensile measurements at SPring-8. The effect of silica filling in situ was larger than that of SIC in the soft composite. The sol-gel reaction of TEOS in the NR latex is supposed to have an advantage in generating an interaction between in situ silica and non-rubber components on the surface of rubber particles through quaternary ammonium ions. This interaction may bring about a unique mechanical properties to the in situ silica filled soft composite. The method using NR latex may be useful for preparation of high performance soft composites.
