Thermal and Radiation Curing of Phenylethynyl Terminated Macromers

Abstract

The thermal and gamma-irradiation induced curing of two phenylethynyl terminated composite resin systems, DFB/BPF and PETI5A, was investigated. Thermal curing of these matrix resin samples was performed at a temperature of 360 °C, gamma irradiation of the samples was conducted at 300 °C at a dose rate of 2.2 kGy h⁻¹. The reaction and subsequent loss of ethynyl groups in the resins for both cure methods was demonstrated by observing the decrease of the 2215 cm⁻¹ peak in the Raman spectra of the resins. Fully cured resin samples were found to have glass transition temperatures of 244–246 °C and 278–280 °C for DFB/BPF and PETI5A respectively. Similar relationships between T_g and fractional conversion were observed in both resins. The apparent polymerization rate, R_p , for thermal cure at 360 °C, was found to be 4:79 × 10⁻²2%s⁻¹ in PETI5A and 3.22 × 10⁻²%s⁻¹ in DFB/BPF. Catastrophic degradation under nitrogen was observed to commence near 450 °C and 530 °C, with 5% weight losses occurring at 455 °C and 540 °C for DFB/BPF and PETI5A respectively. Gamma radiation induced cure at 300 °C was shown to be feasible, with full cure being reached with doses of 40 kGy for DFB/BPF and 100 kGy for PETI5A.