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

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 A degrees C. In the thermal degradation, the 10 % mass loss temperature of the polybenzoxazine is 353 A degrees C and the char yield is about 48 % at 800 A degrees C in nitrogen, while 415 A degrees C and close to 0 % at 650 A degrees C in air.