Infrared spectroscopy evidence for the hydrosilylation of rubbers and hydrogen-containing polysiloxane via heat processing

摘要

The hydrosilylation reaction is very important in silicone-introducing reactions and in the crosslinking of silicone rubbers. In this study, through Fourier transform infrared spectroscopy, the hydrosilylation reaction between hydrogen-containing polysiloxane (H-PDMS) and several kinds of rubber, including styrene-butadiene rubber (SBR), nitrile-butadiene rubber (NBR), chloroprene rubber (CR), and natural rubber (NR), with heat processing was researched. The IR spectra of each compound film were determined after reaction with H-PDMS under 110°C for different times. Through the quantitative estimation of the progress of the hydrosilylation reaction in the course of the heat processing, we established a method for calculating the changes of the peak areas of the Si-H bond and vinyl groups of each sample at each reaction time and computed the ratio of the integral area of Si-H and C=C to that of each compound. The Si-H content decreased 85 and 30% in SBR-Si and NBR-Si, respectively. However, the ratio of the integral area of transmittance of Si-H in NR-Si and CR-Si changed very little during the whole process. The Si-H content decreased less than 20% in NR-Si and CR-Si. All ratios of the integral area of transmittance of the vinyl groups (R _(Vinyl)) of each compound decreased as the reaction time increased at 110°C; the decrease values were very small. The rates of all R Vinyl decreases were slow, and the decreasing sequence was the same as the order of decreasing Si-H content. The hydrosilylation reaction between H-PDMS and SBR was quite smooth in the heat processing and better than that between H-PDMS and NBR. The hydrosilylation reactions of H-PDMS with NR and CR were less satisfying. The results show that polyolefin rubbers can be modified or crosslinked by H-PDMS via heat processing.