Interface And Performance Of Rubber/Boehmite Nanocomposites

A new type filler, boehmite (BM), was utilized for the preparation of rubber basedcomposites. The surface modifications of BM were conducted. The interfacial structures andperformance were investigated fully.First, based on the reactivity of aluminols on the surface and edges of BM, two kinds ofmodifications of BM, with the silane and unsaturated carboxylic acid respectively, wereperformed. Bis-[3-(triethoxysilyl)-propyl]-tetrasulfide (Si69) was used to modify BM. Thechemically grafting of Si69on BM was verified by the results of FTIR and TGA. Theunsaturated carboxylic acids were also found to be effective in modifying BM. The structureof the modified BM was characterized to be the monodentate and bridging bidentate throughesterification and coordination respectively. The surface property of the modified BM wasfound to be substantially changed.We prepared rubber/BM nanocomposites by direct blending. BM was found to beeffective in improving the mechanical properties of SBR and NBR vulcanizates. The tensilestrength and tear strength of NBR/BM composites were3-folded and2-folded compared withthe neat NBR, respectively. Incorporation of Si69in SBR/BM or NBR/BM nanocompositescould further improve the mechanical properties. The interfacial adhesion of SBR/BM andNBR/BM composites was obviously improved by the addition of Si69. Compared withSBR/silica nanocomposites, SBR/BM nanocomposites showed much high dynamic loss in thelower temperature range (-20-0oC). Still, the SBR/BM composites modified with Si69possessed decreased mechanical loss in around60oC. Further, BM was used to partiallyreplace the carbon black in a typical tire formulation. The results demonstrated the capabilityof BM in lowering the rolling resistance and heat build-up.Methacrylic acid (MAA) was used as a novel in situ interfacial modifier for SBR/BMnanocomposites. By the BM/MAA coordination and MAA/rubber grafting reactionmechanism for the modification, the substantiated BM/MAA coordination can improve thedispersion of BM in rubber matrix. It is illustrated that interfacial interaction and the ultimatemechanical performance are significantly enhanced by the in situ modification. The stronginteraction between SBR and BM and the improved dispersion of BM in the SBR matrix areresponsible for the largely enhanced mechanical properties.