Impact resistance enhancement by adding epoxy ended hyperbranched polyester to DGEBA photocured thermosets

Epoxy-functionalized HBP was synthesized and used as toughening additive in epoxy based UV-curable formulations. The addition of the HBP-epox induced an increase of epoxy group conversion, probably through both an activated monomer mechanism, involving the residual hydroxyl groups, and a copolymerization reaction, involving the epoxy functionalities present on the surface of the HBP. Phase separation was reached during UV-Curing, which assured to maintain the good thermomechanical properties of the cured epoxy matrix improving the impact resistance.