Synthesis and characterization of amino-terminated hyperbranched polymer and its effect on impact resistance of epoxy resin thermosets

Amino-terminated hyperbranched polymer (HBP-NH2) was synthesized from diethylenetriamine (DETA) and methyl acrylate (MA) by melt polycondensation through AB3 and AB2 route, and its chemical structure was characterized by attenuated total internal reflectance infrared spectroscopy (ATR-IR) and 1H nuclear magnetic resonance (1H-NMR) spectroscopy. Then, the influence of HBP-NH2 content on the toughness improvement and fractural surface morphology of diglycidyl ether of bisphenol A (DGEBA) cured systems was investigated through impact resistance test and field emission scanning electron microscopy (FESEM), respectively. The results indicated that HBP-NH2 can enhance the toughness of epoxy cured system near 61 % than the neat DGEBA cured thermosets. FESEM images show that the toughness enhancement of epoxy system should be based on shearing deformation mechanism (the thermosets modified with low content of HBP-NH2) and the second phase toughening mechanism (the thermosets modified with high content of HBP-NH2).