Greatly improved thermal properties of polybenzoxazine via modification by acetylene/aldehyde groups

A novel benzoxazine resin (PHB-apa) with low curing temperature, high T-g and excellent thermal stability was developed. Be different from other benzoxazines, PHB-apa contains both aldehyde group and acetylene group on the phenol ring and the aniline ring, respectively. Other benzoxazine monomers contain only one aldehyde group or one acetylene group were chosen for comparison. Their chemical structures were proved by H-1 and C-13 Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The polymerization reaction monitored by Differential Scanning Calorimetry (DSC) and FTIR suggests that the presence of the aldehyde group in PHB-apa leads to a low curing temperature that is benefit for processing. Besides, it is noticeable that this new polybenzoxazine has outstanding thermal property due to the cooperative reaction of the aldehyde group and the acetylene group. Its T-g from Dynamic thermo mechanical analysis (DMA) and char yield at 800 degrees C under N-2 from Thermogravimetric Analysis (TGA) are as high as 459 degrees C and 77.2%, respectively. Such kind of high values is a breakthrough for thermosetting resins, which will allow its application as a heat-resistant material at a much high temperature. (C) 2017 Elsevier Ltd. All rights reserved.