Chemical recycling of glass fiber reinforced epoxy resin cured with amine using nitric acid

An approach to chemical recycling of amine cured epoxy resin using nitric acid solution has been proposed [Dang W, Kubouchi M, Yamamoto S, Sembokuya H, Tsuda K. Polymer 2002;43:2953–8. [1]]. 1,8-p-Menthanediamine cured bisphenol F type (BPF/MDA) epoxy resin was decomposed in nitric acid solution, and then the decomposed product was repolymerized with original resin. In this paper, applicability of the proposed approach to glass fiber reinforced bisphenol F type epoxy resin cured with diamino diphenyl methane (DDM) was investigated. It was concluded that the approach was applicable to BPF/DDM epoxy resin, and potentially to all of amine cured epoxy resin. Flexural strength of the recycled resin was higher than that of virgin resin until the content of the neutralized extract, which was available from degradation of BPF/DDM epoxy resin, was not more than 30 wt% of the original resin. The reinforcement of glass fiber could be separated and recovered. The existence of the reinforcement did not affect decomposition the matrix.