Preparation and properties of polymer microspheres filled epoxy composite films by UV-curable polymerization

Interfacial adhesion between fillers and matrix is important to the properties of their composites. In this study, hollow and solid polymer microspheres/epoxy composite films were, prepared via powder mixing method and UV-curable polymerization. Interfacial adhesion was established by chemical bonding among the epoxy groups of the microspheres and epoxy matrix. The tensile strength and modulus of polymer microspheres/epoxy composite films first increased and then decreased with increasing the content of fillers. The specific tensile strength and modulus of hollow microspheres/epoxy composites were higher than those of solid microspheres/epoxy composites. The fracture mode of the composite films changed from crack of the polymer microspheres to interfacial debonding with increasing the filler's content. Characteristics of shear yielding deformation, particle bridging and crack bowing mechanisms were identified from the microscopic image of tensile fracture surfaces. The improvement of tensile properties compared with neat epoxy resin was discussed on the basis of percolation mechanism. The hollow polymer microspheres/epoxy syntactic foam films retained high electrical resistivity and UV-shielding property. The UV-curable hollow polymer microspheres/epoxy syntactic foam films with good strength could be used as electrical insulating materials. (C) 2016 Elsevier Ltd. All rights reserved.