Pyrolysis Reaction Pathways of Waste Epoxy-Printed Circuit Board

Abstract

Abstract This article elucidates pyrolysis reaction pathways of waste epoxy-printed circuit boards (e-PCBs). Non-isothermal thermogravimetric analyses showed that waste e-PCBs decomposed via a series of reactions distinguished by three apparent reaction regions. The first-stage reaction (<250°C) can be accounted for by the cleavage reaction of N-containing cross-linkage between brominated epoxy resin (BER) and non-brominated epoxy resin (NBER). Evolved gas analysis-mass spectrometry (EGA-MS) showed that the second-stage reaction (250–500°C) can be represented by two independent decomposition reactions of BERs and NBERs to yield thermally stable intermediates. BERs decomposed more rapidly (250–350°C), whereas NBERs decomposed over broader temperature regions (250–500°C) with slower decomposition rates. Multi-shot gas chromatography/mass spectrometry also indicated that brominated compounds, brominated phenol and brominated bisphenol A, are generated mainly at lower temperature zones of the second-stage reg...