Bio-based benzoxazine-terminated hyperbranched polyesters

In this study, a novel bio-based benzoxazine-terminated hyperbranched polyester (HB-Dfa) was designed and synthesized using renewable diphenolic acid and furfurylamine as raw materials through self-polymerization and Mannich condensation reaction . Meanwhile, the copolymers based on HB-Dfa and benzoxazine monomer (P-ddm) were prepared to investigate the effect of HB-Dfa on the properties of traditional benzoxazine. The chemical structure of HB-Dfa was elucidated by fourier transform infrared (FTIR) and nuclear magnetic resonance ( 1 H NMR) spectroscopies. The curing behavior and curing kinetics were investigated by differential scanning calorimetry (DSC), showing that it possessed a low temperature of exothermic peak and activation energy value compared with the P-ddm. Hence, the curing process of P-ddm was facilitated by the introduction of HB-Dfa. The thermomechanical and thermal properties of P-ddm/HB-Dfa copolymers were determined by dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. Compared with the pure P-ddm resin, the introduction of HB-Dfa remained most of glass transition temperature ( T g ), cross-linking density and thermal stability, which could promote the curing reaction and reduce the curing temperature of the copolymers . In addition, HB-Dfa exhibited a low dielectric constant (2.46 ≥  k  ≥ 2.16) and a low dielectric loss ( f  ≤ 0.05) at frequencies range of 2–18 GHz, which could effectively modify the dielectric properties of the copolymer system.