Assessment of the high temperature performance of phenolic—phosphate resin composites

AbstractThe thermal stability of a phenolic‐phosphate resin, prepared by the transesterification of triphenyl phosphate and resorcinol and cured with hexamethylene tetraamine, has been compared with that of a conventional phenolic resin. Thermogravimetric analysis (TGA) of the resins, in air, demonstrated that the phenolic‐phosphate resin had the superior thermal resistance. Accordingly, to assess the performance of phenolic‐phosphate resins as thermally stable binders in composites, long‐term heating ageing studies at 250°C were carried out on asbestos‐filled moulded test specimens. The results of these tests were less welldefined than the TGA results, for the phenolic composite had the higher flexural strength (108.5 MNm−2) initially compared with 56.7 MNm−2 for the phenolic‐phosphate composite. However, after 1000 h heating at 250°C neither system retained a useful level of flexural strength, although the phenolic‐phosphate composite (18.35 MNm−2) was stronger than the phenolic composite (5.4 MNm−2).