Improving the mechanical properties of Glass Reinforced Plastics by slight mechanical compression

Abstract

Glass reinforced plastics (GRPs) are composite materials that have been used widely in engineering. Mechanical properties of fabricated GRP products depend on the type and arrangement of reinforcement, the type of the plastic as well as the reinforcement to plastic ratio. Some of these factors are interdepended in determining the quality of the final product. In the present study, the influence of applying mechanically a slight pressure during fabrication on the properties of GRP specimens, was investigated. Specimens were fabricated using the hand lay-up method and were further processed either by a vacuum bag compression or a mechanically applied pressure. The properties of the produced composite specimens were then determined experimentally. The application of mechanical compression was found to improve their properties. The effect of the mechanically applied compression or vacuum was evident as a reduction of the specimens’ internal void volume compared to the non-compressed ones, resulting in an increase in the density by 9–12% and a reduction in the thickness of the specimens by 15–20%. Additionally, the tensile and flexural strength of the specimens were increased by more than 15% and 5% respectively when pressure was applied mechanically, reflecting an improvement in GRPs’ mechanical properties.