Investigation of Mesoporous silica (KIT-6 and SBA 15-S) effect on property balance of Natural Rubber nanocomposites

Abstract

The prime objective of this dissertation is to synthesize the mesoporous materials Korean Advanced Institute of Science and Technology-6 (KIT-6) and Santa Barbara Amorphous-15 Spherical (SBA-15-S) and utilize these mesoporous silica based materials with elastomers to enhance the properties of tire tread compounds. Mesoporous silica based elastomers are developed to get better physical, mechincal and thermal properties and to synthesize materials that are environmental friendly. These filler reinforced elastomers were tested under different conditions and the properties that were analyzed are torque, scorch time. The combined studies of mesoporous silica based materials and elastomers showed that these novel materials lead to promising structural and mechanical properties. The degradation of carbon black treads have adverse effects on environment so the world is looking for alternative materials that can replace carbon black. Silica is one of the materials that was under observation for the last few decades but reinforcement level is not same provided by silica as compared to carbon black. Amorphous silica and precipitated silica have also been used in tires for many years but these tires are suffering from increased mass, higher thickness and higher noise level. Silica can reduce the green house gas emissions as well. In this study meso-porous silica materials have been synthesized and utilized as fillers in Styrene Butadiene Rubber (SBR) to investigate their effect for tire tread compounds. For this purpose, KIT-6 is synthesized by dissolving 11.8g of HCl in 217g of deionized water and mixing 6g of P123 in it under constant stirring. When uniform solution is formed add 6g of 1-butanol under constant stirring at 35oC. After 1 h, add 12.8g of Tetraethyl ortho silicate drop wise keeping the temperature constant. The resulting solution is kept under constant stirring for 1 day at 35oC. After this the solution is shifted to Teflon bottle and placed in oven for 1 day at 100oC for hydrothermal treatment. The obtained solution is filtered and dried, the solid product is then calcined at 550oC for 5 h and utilized as a filler in elastomers. SBA-15-Spherical is synthesized by dissolving 23.6g of HCl in 80g of deionized water and adding 4g of P123 under constant stirring at 35oC. As the uniform solution is formed take 40g of deionized water and add 3.04g of KCl in it separately at 25oC. Now add this solution to the first one and keep it under stirring for 1 h at 35oC. Then 3g of mesitylene is added and the solution is kept under stirring for 2 h. After that 8.5g of tetraethyl ortho silicate is added drop wise and stirred for 10 – 20mins. The solution was kept under static condition for 1 day and then shifted to Teflon bottle and kept in oven at 100oC for 1 day. The solution is hydrothermally treated which is then filtered and dried. The solid product retained after filtration is calcined at 550oC for 5 h and used as a filler. The synthesized Mesoporous silicas KIT-6 and SBA-15-Spherical are characterized by SEM-EDS, XRD, BET and FT-IR analysis for their conformity.The surface modification of meso-porous silica materials is done by dehydrating meso porous silica for 3 h at 200oC to remove adsorbed moisture. Meso-porous silica materials are grafted in dried toluene using 3-aminopropyltrimethoxysilane as amine source. Then 1g of respective meso-porous material is dispersed in 50ml of dried toluene and 3ml of AP (3- amino propyltrimethoxysilane) are added to the suspension, which is further kept under reflux for 20 h. The solid product is recovered by filtration and repeatedly washed out with toluene and octane and dried overnight at 80oC . These silylated and non-silylated meso-porous silica materials are reinforced in NR (natural rubber) to form nano composite. These nanocomposites were formed by adding 6 phr (parts per hundred parts of rubber) of meso-porous silica into NR. After the reinforcement of these functionalized and non-functionalized meso-porous materials KIT-6 and SBA-15-S into natural rubber (NR) along with the curatives the thermal and mechanical properties of these nanocomposites are determined.