In situ binary sol–gel reaction of various trifunctional alkoxysilane in the silane‐grafted polyolefin matrix and its effect upon the mechanical properties

The vinyltrimethoxysilane‐grafted ethylene‐propylene copolymer/trifunctional methoxysilane (EPR‐ g ‐VTMS/RTMS) composites were prepared via in situ silica sol–gel reactions. Five trifunctional methoxysilane compounds ( n ‐hexyltrimethoxysilane, n ‐decyltrimethoxysilane, n ‐tetradecyltrimethoxysilane, n ‐octadecyltrimethoxysilane, and phenyltrimethoxysilane) have been selected for this study. The water‐cross‐linked EPR‐ g ‐VTMS/RTMS composites were characterized by attenuated total reflectance‐Fourier transform infrared spectroscopy, gel content, solid‐state 29 Si CP/MAS NMR, wide‐angle x‐ray scattering, tensile strength, and field emission scanning electron microscopy measurements. The type of RTMS additive has a substantial influence on the nature of siloxane band networks and eventually the mechanical tensile properties. This finding suggests that the interaction and/or entanglement between the EPR‐ g ‐VTMS matrix and the substituent of the RTMS additives are crucial for the modifying mechanical properties. Moreover, for the water‐cross‐linked EPR‐ g ‐VTMS/C n TMS ( n = 6, 10, 14, and 18) composites, the joint evidence provided by attenuated total reflectance‐Fourier transform infrared spectroscopy, 29 Si CP/MAS NMR, and wide‐angle x‐ray scattering results suggested the formation of ladder‐type poly( n ‐alkyl silsesquioxane)s and the presence of the highly ordered structure with a thickness equal to the length of two n ‐alkyl groups in all‐ trans conformation. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers.