Development of eco friendly hybrid sandwich composites based on cardanol derivatives for light weight applications

Abstract

This is an age where mankind can boost of what the power of thinking can achieve; from unravelling the mysteries of earth to travelling beyond this planet in search of the unknown. This progressive journey can be credited to the development of new age materials that can be relied upon for specific applications. Syntactic foams are hollow particle filled polymers well known for their strength to weight ratio. These are employed as core materials in sandwich composites which find wide spread applications in aeronautical, space and marine structures. These high-end applications make it necessary to comprehend their characteristics under various test conditions. Various polymer matrixes can be used for the preparation of syntactic foams. Diglycidyl ether of bisphenol A (DGEBA) epoxy resin is commonly employed polymer matrixes. A major setback of this polymeric resin is its poor resistance to crack initiation and growth. Epoxy resin is thus known to be brittle and also has low impact strength. This research work aims at improving the toughness of epoxy resin by partial or complete replacement of the DGEBA epoxy with a bio based substitute. The epoxy with improved toughness is employed for the preparation of syntactic foam core hybrid sandwich composites. The toughness of epoxy resin is improved by two different methods. First method involves the replacement of conventional curing agent with phenalkamine; a new class of curing agent for epoxy resin. It is a bio-based curing agent that is synthesised using cardanol extracted from cashew nutshell liquid. Second method consists of complete replacement of the synthetic DGEBA epoxy by a green substitute based on cardanol. With this aim, epoxidation of cardanol is carried out. newline