Abstract:

6-Methyl-3-methacryloxyethyl-3,4-dihydro-2H-benzo[e][1,3]oxazine(MEBM) was synthesized by simple esterification reaction of 2-(6-methyl-4H-benzo[e][1,3]oxazin-3-yl)-ethanol(MB-OH) with methacryloyl chloride. MBEM/N-Phenylmaleimide copolymer[P(MBEM-co-NPMI)] was synthesized with N-phenylmaleimide(NPMI) and MBEM by free radical solution polymerization using azodiisobutyronitrile(AIBN) as initiator and toluene as solvent. The corresponding polymers of PMB-OH, PMBEM and P[P(MBEM-co-NPMI)] were obtained by thermal cross-linking of MB-OH, MBEM and P(MBEM-co-NPMI), respectively. The molecular weight of the resulting copolymer was determined by gel permeation chromatography(GPC). The structure and chemical composition of MBEM and P(MBEM-co-NPMI) were characterized by Fourier transform infrared spectroscopy(FTIR) and nuclear magnetic resonance spectroscopy(¹H NMR, ¹³C NMR). The curing behavior of all substances was also studied by differential scanning calorimetry(DSC) and FTIR. Thermal properties of the cross-linking polymers of PMB-OH, PMBEM and P[P(MBEM-co-NPMI)] were investigated by dynamic mechanical analysis(DMA) and thermal gravime-tric analysis(TGA). The results show that the temperatures in maximum loss factor of the cross-linking polymers of PMB-OH, PMBEM, and P[P(MBEM-co-NPMI)] are 92, 129, and 181℃, respectively. The temperatures in maximum loss modulus of the cross-linking polymers of PMB-OH, PMBEM and P[P(MBEM-co-NPMI)] are 56, 91 and 156℃, respectively. Under N₂, the temperatures of the cross-linking polymers of PMB-OH, PMBEM and P[P(MBEM-co-NPMI)] at 5% mass loss are 257, 244 and 260℃, respectively, and the temperatures at 10% mass loss are 280, 266, 284℃, respectively. Their ultimate char yields are 23.2%, 17.8% and 14.0% at 800℃, respectively. These results suggest that P[P(MBEM-co-NPMI)] has excellent heat resistant performance.

Key words: Benzoxazine, Methacryloyl chloride, N-Phenylmaleimide, Thermal property