Synthesis and modification of epoxy resins using recycled poly(ethylene terephthalate)

Abstract

AbstractDevelopment of a method of degradation of poly(ethylene terephthalate) (PET) wastes for the preparation of materials for the synthesis and modification of epoxy resins, development of a method of preparation of epoxy resins, characterization of epoxy resins so prepared, and optimization of the composition of epoxy resins modified with recycled materials were the goals of this work. Therefore, the conditions required for the strong degradation of waste PET by glycolysis reaction were chosen. Glycols with different length of alkyl chain were tested. Composition and structure of the degradation products were determined by GPC and spectroscopic methods (i.e. FT‐IR, 1H‐NMR, and 13C‐NMR). Next, the products of waste PET glycolysis were used as polyhydroxylic reagents for the synthesis of epoxy resins by their reaction with epichlorohydrin. Bis(2‐hydroxyalkyl)‐terephthalate was used as a model compound. The products were applied in the preparation of compositions with Bisphenol A‐based low‐molecular‐weight epoxy resins. It was found that modification of epoxy resins with the products of PET degradation led to the improvement of their tensile and flexural strengths, hardness, and thermal stability. Better results were obtained for the products with longer alkyl fragments. The incorporation of alkylether chains from PET glycolysis not only increased water absorption of the modified resins, but also improved their chemical stability against 10% HNO3, 75% H2SO4, and ethyl acetate. Copyright © 2008 John Wiley & Sons, Ltd.