Pyrolysis of brominated polyethylene as an alternative carbon fibre precursor

Polyethylene as a polymeric precursor for carbon fibre production has attracted much attention over recent years. Not only is it a low-cost commodity polymer, it has a higher theoretical carbon yield (at 100%) than polyacrylonitrile (at 67%) and is very readily melt processed into fibres. The challenge is to efficiently dehydrogenate and graphitize polyethylene fibres. This paper explores the use of bromine as a novel oxidant to functionalise polyethylene prior to carbonisation, leading to efficient cyclisation and carbonisation on heating. Through a process of low-temperature photo-induced liquid-phase bromination followed by dehydrobromination at moderate temperature and subsequent carbonisation to 800 degrees C, a carbonaceous product was obtained in high carbon yield (>90%). The effects of a range of process conditions, as well as the use of different types of polyethylene and polyethylene blends, were explored. (C) 2019 Elsevier Ltd. All rights reserved.