Mechanical properties of silane‐treated silica particle‐filled polyisoprene composites: Influence of the alkoxy group mixing ratio in silane coupling agent containing mercapto group

Abstract

Spherical silica particles were treated with a mixture of silane coupling agents with mercapto functional groups and dialkoxy or trialkoxy groups. The surface coverage, which indicates the number of layers covering the silica surface, was in the range from 1.6 to 6.0. The molecular mobility of the treated layer was analyzed with 1H‐NMR spectroscopy. The silane chain became more flexible with increasing dialkoxy structures in the mixture and with increasing surface coverage. The stress–strain behavior was measured for a composite consisting of the treated silica and vulcanized polyisoprene rubber (PIR). There was no influence of the dialkoxy and trialkoxy mixing ratio for near monolayer coverage. In the case of the pure dialkoxy and low trialkoxy contents, a higher stress was observed at the same strain for surface coverages of 2.4–3.8. However, a longer length flexible silane chain, that is, with a surface coverage of 6.0, was disadvantageous for the reinforcement effect. The results of pulse NMR analysis of the unextracted PIR on the particle surface and swelling test indicate that the reinforcement effect was strongly affected both by entanglement and the crosslinking reaction between the silane chain and PIR at the interfacial region. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Influences of the alkoxy group number and treatment condition on the structure of glycidoxy functional silane-treated layer on silica particles analyzed by1H pulse NMR

“…The glycidoxy functional silane is widely utilized for reinforcement of the interface for silica particle-filled epoxy resin, such as the encapsulating resin for a semiconductor chip. The surface treatment of silica particles with glycidoxy functional silanes was performed under the same conditions as that for the previously reported mercapto functional silanes [5,7,8]. The influence of the organic functional group of the silane on the molecular mobility of the silane layer on the silica particle surface is discussed with comparison of the previous [5,7,8] and present results.…”

“…Surface treatment was conducted in the same way as previously described [5,7,8]. The amount of silane required for monolayer coverage of the silica particles was calculated as previously described [5,7,8], using the area occupied by a single silane molecule and the specific surface area values of the silica particles.…”

“…The amount of silane required for monolayer coverage of the silica particles was calculated as previously described [5,7,8], using the area occupied by a single silane molecule and the specific surface area values of the silica particles. The quantity of silane is given as surface coverage,…”

“…The network density of the silane-treated layer on the silica particles could be controlled by varying the mixing ratio of di-alkoxy/tri-alkoxy structures. Treated silica particles were mixed with a polyisoprene rubber (PIR) matrix and vulcanized, and the effects of di-alkoxy/tri-alkoxy mixing ratio on the stress-strain characteristics of the filled PIR were investigated [5,8]. The stress at the same strain increased due to silane treatment, and was higher for the di-alkoxy structure and lightly crosslinked network structure than other structures above 300% strain.…”

“…We have investigated the effect of interfacial adhesion between inorganic fillers surface-treated with various silane coupling agents and a matrix polymer on the mechanical properties of these composites [1][2][3][4][5][6][7][8]. Surface treatment of spherical silica particles using a silane coupling agent with a mercapto group was previously [7] conducted and the structure of the silanelayer formed on the silica surface was analyzed by 1 H pulse nuclear magnetic resonance (NMR).…”