Research on block copolymer toughened hydrophobic CEP insulation materials

Commercial hydrophobic cycloaliphatic epoxies (Hydrophobic CEP) with good weatherability have been used as outdoor insulator materials in recent years while their properties of crack resistance and toughness are concerning topics because of their brittle alicyclic structure. Block copolymer (BCP) can self-assemble into the spherical structure in the liquid epoxy system due to its amphiphilic feature and the nano-scale BCP sphere homogeneously embedded in epoxy can act as toughener and show the good toughening effect. The performances of filled and unfilled hydrophobic CEP system toughened by low loading level BCP tougheners, including thermal property, mechanical properties, fracture toughness and low temperature cracking was investigated. BCP toughened epoxy showed improved elongation at break, increasing of fracture toughness, similar thermal stability and a little decreased modulus compared to normal hydrophobic CEP systems. With the improved performance and comparable processability, BCP toughened epoxy system could be used for electrical industry, especially for outdoor application.