Studies of anhydride-cured epoxy networks with bonded and unbonded polyhedral oligomeric silsesquioxane (POSS)
Teo, Herman Jun Kai
Date of Issue2011
School of Materials Science and Engineering
This work is focused on the effect of polyhedral oligomeric silsesquioxane (POSS) compounds bearing reactive and non-reactive groups on the properties of resultant epoxy-anhydride hybrids and the underlying mechanisms. With rapid developments in nanotechnology, there has been great interest in polymer nanocomposites such as epoxy-based hybrids. POSS compounds have been incorporated in amine-cured epoxies for property improvements. In contrast, POSS/epoxy hybrids based on anhydride cure agents are seldom studied due to challenges such as the kinetically-controlled cure process and the requirement of catalysts for effective curing which may lead to complex reaction kinetics. However, the benefits of longer pot lives, better controlled curing, higher thermal and dimensional stabilities may outweigh the detriments. Kinetics, morphological and thermal studies were carried out to elucidate the effect of a POSS-epoxy on the properties of an epoxy-anhydride system in which the epoxy has self-catalytic sites. The POSS tether length difference on the cure kinetics was investigated. Tailoring POSS tether chemistry to reduce the cure kinetics difference between resin components was also studied with a novel POSS-anhydride. Anhydride-cured epoxy hybrids containing POSS-imidazolium (POSS-IMC) surfactants and corresponding modified clays have been prepared. Their catalytic effects were examined with correlation to the resultant morphologies and impact on the thermal properties. Interfacial interactions of non-reactive POSS on the thermal properties of epoxy-anhydride hybrids have also been investigated with octa-phenyl POSS (OPS) and its brominated derivatives.