Effect of trace diphenyl phosphate on mechanical and thermal performance of polyimide composite films

How to achieve polyimide (PI) with better thermal and mechanical properties is a great challenge. In this study, flame-retardant diphenyl phosphate (DPhP), was incorporated in to heterocyclic diamine contained PI films to form phosphorus-polyimide composite films (P-PIs). The structures, element distribution, thermal and mechanical properties of P-PIs were characterized by FT-IR, SEM, EDS, DMA, TGA, and tensile test. The results indicated that the incorporation of phosphorus can significantly enhance the thermal and mechanical properties. The 5% weight loss temperature in air and the glass transition temperature (Tg) of P0.6-PI film were 577 and 405 °C, which were 50 and 16 °C larger than the neat PI film, respectively. In addition, the P0.6-PI film also showed improved tensile strength, modulus and toughness by 47%, 57% and 76%, respectively, as compared to the neat PI film.