Synthesis and characterization of aramid composites reinforced with silanized graphene platelets

Abstract

The synthesis and characterization of aramid composites reinforced with graphene platelets are reported. Hydroxy-functionalised graphene platelets were modified with two sol–gel binders (aminopropyl- or aminophenyl-trialkoxysilanes) and then chemically linked with aramid chains. The effect of the two sol–gel binders on the physiochemical and mechanical properties was evaluated. Chemical changes during the sol–gel reaction and subsequent amidation process in the nano-composite preparation were evaluated by the XPS and FTIR analyses. Thin films of these composites with different proportions of graphene were prepared. Morphology of the hybrids prepared was studied by the SEM technique. Properties of the composite films were studied by dynamical mechanical thermal (DMT) analysis to measure their glass transition temperature (T_g) and storage modulus. These properties have been compared with previously reported values using pristine graphene (Gr) as a filler. The increase in thermal mechanical properties on addition of silanized graphene (SiGr) showed a large shift in the T_g and more increase in storage modulus by chemically binding SiGr sheets on the aramid chains. Aminophenyl-trialkoxysilane was found to give better results due to the presence of phenyl groups which were more rigid than propyl groups present in aminopropyl-trialkoxysilane. The effect of chemical bonding and the possible π–π secondary bond interactions between the matrix and graphene platelets on the properties of the resulting hybrids are discussed.