Research On Synthesis And Properties Of Urushiol-based Benzoxazine

A series of urushiol based benzoxazine monomers containing saturated aliphatic amine, unsaturated aliphatic amine and aromatic amine had been prepared by solution method using the main components of the Chinese lacquer, urushiol as phenol source, formaldehyde as aldehyde source and primary amine compounds as amine sources. The molecular structures of the obtained benzoxazine monomers were characterized and the polymerization reactions were studied. The contents were shown as follows:1. Urushiol based benzoxazine monomers UBz-1, UBz-2and UBz-3were synthesized utilizing urushiol, formaldehyde and saturated aliphatic amines including n-propylamine, n-hexylamine and n-octylamine. The chemical structures of benzoxazine monomers were identified by fourier-transform infrared spectroscopy (FTIR) and1H nuclear magnetic resonance spectroscopy (1H NMR). Differential scanning calorimetry (DSC) and FTIR were used to monitor the curing process of benzoxazine monomers. The thermal properties of obtained polybenzoxazines were evaluated by DSC and thermo gravimetric analyses (TGA). The results showed that the polymerization of the monomers could be starting at a relatively lower temperature than regular benzoxazines, and the temperature of polymerization became low with the increasing of the aliphatic chain in the aldehyde source. The obtained polybenzoxazines showed good thermal stability properties.2. Urushiol based benzoxazine monomers UBz-4and UBz-5had been synthesized using urushiol, formaldehyde and unsaturated aliphatic amines including allylamine and propargyl amine. Subsequently, the benzoxazine monomers were thermo-cured into the polybenzoxazines. Their chemical structures were identified by FTIR and1H NMR. The curing reactions of both monomers were monitored by DSC and FTIR. The thermal properties of polybenzoxazines were evaluated by DSC and TGA. The results showed that the monomers could be cured at a low temperature and the thermal properties of obtained polybenzoxazines were higher than the urushiol-based polybenzoxazines containing saturated aliphatic amine. 3. Urushiol based benzoxazine monomer UBz-6was prepared from urushiol, formaldehyde and p-toluidine using the molar ratio of1:2:1, the corresponding polybenzoxazine (PUBz-6) was obtained by the thermal-curing of UBz-6. The chemical structure of UBz-6was determined by FTIR and1H NMR spectroscopy. The curing reaction of UBz-6was monitored by DSC and FTIR. The thermal property of obtained polybenzoxazine was investigated by DSC and TGA. The results showed that the obtained polybenzoxazine PUBz-6was one novel polybenzoxazine resin with high Tg (237℃).4. The toughness properties of benzoxazine resins were modified with the E-51epoxy resin. The curing behavior of the blends between benzoxazine monomer UBz-6and E-51epoxy resin (UBZ-6/E-51) was monitored by DSC. The thermal mechanical property and thermal stability of UBz-6/E-51copolymers were evaluated by dynamic mechanical analysis (DMA) and TGA. The results showed that temperature of thermal-curing decreased and the toughness of polymers was further improved.