Towards understanding the breakdown and mechanisms of glass fiber reinforced polyester composites in sub-critical water using some of the most employed and efficient additives from literature

This study describes the hydrolysis of glass fiber reinforced unsaturated polyester (UP) composites using some of the most employed and efficient additives from the literature. This includes the use of KOH, a mix of KOH/phenol and reference experiments without additives. Sub-critical water in a temperature range of 200–325 °C and a constant pressure of 300 bar were chosen as process parameters to cover a wide temperature range. It was possible to explain the mechanisms producing the majority of the different reaction products identified by GC-MS. The monomer phthalic anhydride was only recovered in the experiments without additives and was most stable at 200–250 °C. The increase or decrease in the production of monomers and other reaction products at different temperatures with and without additives has been clarified by the GC-MS investigations, which introduces new possibilities for tailoring the production of monomers and various chemical compounds via hydrolysis of polymer composites.