Directly grafting octa(aminophenyl) polyhedral oligomeric silsesquioxane onto carbon fibers for superior interfacial strength and hydrothermal aging resistance of silicone resin composites

Abstract

Introducing nano-scale reinforcements into carbon fiber (CF)-matrix interface is a useful method to enhance interfacial strength of composites. In this work, we demonstrated a facile and high efficient strategy of preparing octa(aminophenyl) polyhedral oligomeric silsesquioxane (OapPOSS)/CF hierarchical reinforcements (CF-g-POSS) by directly grafting OapPOSS on CFs by covalent bonding. OapPOSS distributed on fiber surfaces uniformly, and enhanced surface polarity as well as roughness significantly. CF-g-POSS exhibited a low contact angle and high surface free energy, which helped to change the wettability between CF and the matrix. Simultaneous enhancements of interfacial shear strength (IFSS) and interlaminar shear strength (ILSS) of CF-g-POSS/methylphenylsilicone resin (MPSR) composites were achieved, increasing 47.83% in IFSS and 59.04% in ILSS compared to those of untreated composites. These enhancements could be attributed to OapPOSS interface with providing sufficient covalent bonding and strong mechanical interlocking. Additionally, anti-hydrothermal aging behaviors were also increased obviously owing to the introduction of SiOSi bonds at the interface.