Curing studies and mechanical properties of glass fiber reinforced composites based on silanized clay minerals

A commercial organically modified montmorillonite Cloisite® 15A was modified via a new silanization route by two different silane coupling agents: 3-Aminopropyltriethoxysilane and 3-Glycidyloxypropyltrimethoxysilane. This method enables the use of very high concentration of silanes for functionalization of clay minerals. The ratio of weight of silane coupling agent to that of weight of clay mineral (X) was varied from 0.1 to 6. Small angle X- ray scattering and thermogravimetric analysis were carried out on silane modified clay minerals to quantify the grafting of silanes as a function of ratio of weight of silane agent to that of clay mineral. Fiber reinforced epoxy nanocomposites containing silylated clay minerals were manufactured using vacuum assisted resin infusion molding method. Also, curing studies were carried out on fiber reinforced epoxy nanocomposites containing Cloisite® 15A at different cure temperatures, e.g. 70 °C, 80 °C, 85 °C, 95 °C and for two different curing time periods, e.g. 7 h and 10 h. Significant improvements in mechanical properties of fiber reinforced nanocomposites were obtained with incorporation of clay minerals silanized using high concentration of silanes in solvent and chosen curing schedule. The tensile modulus, tensile strength, flexural modulus and bending strength increased by 30%, 37%, 139% and 146% respectively, in nanocomposites containing clay mineral modified using 4X aminopropyltriethoxysilane. An attempt has been made to correlate the results with the morphology of nanocomposites by transmission electron microscopy and that of fractured surfaces by scanning electron microscopy.