Investigation into the use of metal oxides for catalysed epoxy resin decomposition

An investigation into catalysed thermal decomposition of epoxy resin was carried out with the goal to improve the commercial viability of glass fibre reinforced plastic recycling. A variety of metal oxides were examined to find their ability at reducing current limitations associated with thermal recycling methods such as high operating temperatures and exposure time to such environments. Thermogravimetric analysis (TGA) was utilised to determine the effect of copper (II) oxide (CuO), titanium (IV) oxide (TiO2) and cerium (IV) oxide (CeO2) on epoxy degradation. CuO and CeO2 provided a reduction in second stage degradation onset temperature of around 60°C under a nonisothermal heating rate of 10°C/min; however, TiO2 exhibited no such ability. Under isothermal heating conditions, at a temperature of 500°C, all metal oxides provided a reduction in full epoxy decomposition time. CuO yielded the fastest epoxy degradation, reducing it by 12 minutes compared to epoxy alone. The epoxy first and second degradation stage activation energies were found through a kinetic study; with and without the addition of the metal oxides. It was observed that CuO transformed the epoxy degradation into a one stage process at heating rates of 30°C/min and above. CeO2 lowered the second stage activation energy however TiO2 caused an increase in both cases. The reduction in epoxy thermal decomposition temperature and time presented by CeO2 and CuO is believed to be sufficient justification for further investigation. Future work will focus on how the improvement in recycling conditions can translate into recovered glass fibre strength retention.