Polymerization behavior and thermal properties of benzoxazine based on 4,4′-diaminodiphenyl ether

Abstract

The thermally activated ring-opening polymerization behavior of benzoxazine based on 4,4′-diaminodiphenyl ether was investigated by Fourier transform infrared and differential scanning calorimetry, and the thermal properties of the corresponding polybenzoxazine were studied by dynamic mechanical analysis, thermogravimetry-mass spectrometry, and differential thermal analysis. In the ring-opening polymerization reaction, the C–O–C absorption peak of the oxazine ring at 1,054 cm–1 disappeared first, and the C–N–C absorption intensity of the oxazine ring decreased gradually with time rising. The activation energies of the non-isothermal polymerization are 83.4 and 87.4 kJ mol–1 evaluated with Kissinger and Flynn–Wall–Ozawa methods, respectively. Dynamic mechanical analysis shows the glass transition temperature of the resultant polybenzoxazine is 188 °C. In the thermal degradation, the 10 % mass loss temperature of the polybenzoxazine is 353 °C and the char yield is about 48 % at 800 °C in nitrogen, while 415 °C and close to 0 % at 650 °C in air.