Comparison of coupling effectiveness among amino-, chloro-, and mercapto silanes in chloroprene rubber

Abstract

The present work focuses mainly on the uses of silane coupling agents in chloroprene rubber (CR) reinforced with precipitated silica (PSi). Grafting of organoalkoxysilane onto surfaces of PSi was conducted, and the characteristics of surface-modified PSi were determined by BET technique, light-scattering particle size analysis, DRIFT and29Si NMR spectroscopy. The 3 types of silane coupling agents used in this work were as follows: 3-aminopropyl triethoxysilane (APTES), 3-chloropropyl triethoxysilane (CPTES) and bis (3-triethoxysilylpropyl) tetrasulfide (TESPT). Processability of compounds and mechanical properties of vulcanizates were then investigated, and compared for the effectiveness of silane coupling agents used in property enhancement. The results reveal that the silane type affects not only the compound processability, but also the vulcanizate mechanical properties. Among 3 silanes, the CPTES and TESPT are capable of reducing the fillerfiller interaction to greater extent than the APTES, leading to superior compound processability. Moreover, the amino and mercapto groups of APTES and TESPT, respectively, significantly enhance the mechanical properties of CR vulcanizate more effectively than the chloro groups of CPTES. This might be ascribed to the combined effects of enhanced rubber-filler interaction and improved filler dispersion. © (2013) Trans Tech Publications, Switzerland.