Synthesis of Polyhedral Oligomeric Silsesquioxane mixture and characterization of hybrid epoxy composites

This paper attempts to study the relationship between the various properties and different composition of the Polyhedral Oligomeric Silsesquioxanes (POSS) mixture hybrid epoxy composites, and two kinds of low cost POSS mixtures containing diversified structure have been synthesized by polycondensation method, which could be applied as potential alternatives of expensive commercialized POSS. Lower permittivity can be obtained by incorporating POSS mixture, but permittivity value did not follow the change of content of POSS mixture. The improved AC breakdown strength was achieved with adding 5 wt% POSS mixture. Thermal properties were tested using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA), glass transition temperature of composites were increased with addition of 5 wt% POSS mixture and then decreased with higher content, while thermo-oxidation resistance of composites has significantly improved with increasing content of POSS mixture. Besides, the tensile strength of composites has no obvious change by incorporating POSS mixture in the epoxy resins, and the morphology of composites analyzed by scanning electron microscope-energy dispersive X-Ray spectroscopy (SEM-EDS) revealed the similar fracture mode of neat epoxy resin and composites and showed good compatibility between POSS mixture and epoxy.