Synthesis and properties of modified PMR-matrix resin type polyimide and composite with non-carcinogenic diamine

Abstract

Modified PMR prepolymer was prepared using the bis(3,5-dimethyl-4-amino phenyl)phenyl methane and characterized by elemental analysis and Fourier transform infrared (FTIR), proton (1H) and carbon-13 (13C) nuclear magnetic resonance (NMR) spectral techniques. Differential scanning calorimetry analysis shows that melting and curing take place in the temperature range 205–230°C and 255–330°C, respectively. The uncured and cured prepolymer undergo two-step (317 and 347°C) and single-step (559°C) decomposition, respectively. The temperature of 10% weight loss and char yield at 1000°C were found to be 450°C and 36 wt%, respectively. FTIR and thermogravimetric analyses of the modified-PMR resin powder and fully imidized prepolymer, heat treated at different temperatures, reveal that imidization and cross linking happen in the temperature range 250–275°C and 275–325°C, respectively. The prepolymer was found to undergo photo-cross linking (271 nm). Carbon fibre (T300)-reinforced modified PMR composite was found to have a flexural strength of 469 MPa, flexural modulus of 50 GPa and interlaminar shear strength of 34 MPa.