Understanding physical changes and strength loss of E-glass fibres following exposure to elevated temperatures

The strength loss of glass fibres (GF) following exposure to elevated temperatures is a long-established phenomenon, yet the mechanism or mechanisms responsible for the strength decrease are not fully understood, aside from acknowledgement that surface flaws must become more severe by some means. As disposal of GF based composite materials by landfill has become untenable in many regions, interest in composite recyclability has increased. Separation of GFs from thermosetting polymers generally requires the use of high temperatures, which produces very weak fibres with minimal commercial value. In this context an understanding of the strength loss mechanisms is of importance in terms of efforts to mitigate fibre damage or to recover the strength of previously heated fibres. In addition to fibre strength loss, numerous other physical and chemical changes to heat treated (HT) or recycled GF have been described in the literature