Curing kinetics, thermal, and adhesive properties of acetylene‐terminated benzoxazine

The acetylene-terminated benzoxazine monomer (BB-apa) has been synthesized using 2,2-bis(4-hydroxyphenyl)butane, 3-aminophenylacetylene, and paraformaldehyde. The structure of the monomer was characterized by FTIR spectroscopy and 1H NMR spectra, which indicated that the reactive oxazine ring and acetenyl groups existed in molecular structure of BB-apa. The polymerization behavior was monitored by FTIR and non-isothermal differential scanning calorimetry (DSC), which showed that the BB-apa had completely cured with multiple polymerization mechanisms according to oxazine ring-opening and ethynyl addition polymerization. The curing kinetics results revealed that the introduction of ethynyl groups can accelerate the ring-opening polymerization of benzoxazine, leading to a lower curing temperature and apparent activation energy. Moreover, the thermoset derived from the BB-apa exhibits higher thermal stability and lap shear strength (at 350 °C) with the glass transition temperature of 353 °C compared with the traditional benzoxazine polymer without ethynyl groups (BB-a). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44547.