Thermal and radiation curing of phenylethynyl terminated macromers

The thermal and gamma-irradiation induced curing of two phenylethynyl termi nated composite resin systems, DFB/BPF and PETI5A, was investigated. Therma l curing of these matrix resin samples was performed at a temperature of 36 0 degrees C, gamma irradiation of the samples was conducted at 300 degrees C at a dose rate of 2.2 kGy h(-1). The reaction and subsequent loss of ethy nyl groups in the resins for both cure methods was demonstrated by observin g 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 degrees C and 278-280 degrees C for DFB/BPF and PETI5A respectiv ely. Similar relationships between T-g and fractional conversion were obser ved in both resins. The apparent polymerization rate, R-p, for thermal cure at 360 degrees C, was found to be 4.79 x 10(-2)% s(-1) in PETI5A and 3.22 x 10(-2)% s(-1) in DFB/BPF. Catastrophic degradation under nitrogen was obs erved to commence near 450 degrees C and 530 degrees C, with 5% weight loss es occurring at 455 degrees C and 540 degrees C for DFB/BPF and PETI5A resp ectively. Gamma radiation induced cure at 300 degrees C was shown to be fea sible, with full cure being reached with doses of 40 kGy for DFB/BPF and 10 0 kGy for PETI5A.