Thermal-oxidative reclamation of natural rubber reinforced with silica

Abstract

The reclamation law of natural rubber reinforced with silica （SNR) swollen by a small amount of soybean oil at different temperatures and in different time was studied, and the chemical composition and micromorphology of the reclaimed pro-ducts were determined. The results showed that within the temperature range of 160 and 240 ℃, the sol content of SNR increased continuously with the increasing temperature after swollen by soybean oil of 20 phr （mass), and when reclaimed at 220 ℃ for 15 min, the mass fraction of sol in the reclaimed product increased to 50.5%, and the mass fraction of sol in the reclaimed product was only 28.7% at 200 ℃, which indicated that 220 ℃ was an important turning point temperature in the reclamation process of SNR. The increase in oxygen content in the reclaimed product was due to the violent oxidation reaction of SNR during the reclamation process. In addition, as the degree of reclamation increased, the thickness of bound rubber of loose strata on the surface of silica decreased from 25 nm to 8 nm, indicating that thermal-oxidative reclamation could achieve a high degree of detachment between nano silica and its surface bound rubber.

Keywords

• green tire; silica， natural rubber，reinforcement， soybean oil， oxidative reclamation， bound rubber of loose strata，