Study On Properties Of Epoxy Resins Modified By Inorganic Nano-particles And Polyurethane

For the excellent properties performed in material mechanics, electrical insulating and adhesion, epoxy is celebrated and holds a dominant position in global three universal thermoset plastics. Though epoxy has been used in a wide variety of engineering applications, the disadvantages of epoxy restrict a further application occurred in high level. There are many methods for modified epoxy. Previous studies mainly based on single modification methods, but the real way to merge two or more rarely. In this paper, the epoxy resin was modified by thermoplastic polyurethane and inorganic particles then prepared nanocomposite material which had better synergistic effect than the resin modified with a single mothed.PU-EP precursor was prepared by epoxy as matrix, polyurethane as toughening agent, methyl tetrahydrophthalic anhydride as the curing agent. The optimal content of polyurethane was 30wt% in the PU-EP precursor by the mechanical properties and thermal stability testing. SiO₂/PU-EP nanocomposite was prepared by PU-EP as organic precursor and nano-silica as filler. The mechanical properties, thermal stability and electrical property of composites were investigated by electronic tensile machine, TGA, dielectric spectrum analyzer, high resistance meter and withstand voltage tester. The results showed that doping of appropriate amount of nano-silica could improve mechanical properties and thermal decomposition temperature of nanocomposite, the shear strength and impact strength of 2wt% SiO₂/PU-EP were increased to 27.40MPa and 25.07KJ/m². Dielectric constant and dielectric loss were increased compared to the pure epoxy, the volume resistivity and the breakdown strength of SiO₂/PU-EP nanocomposite decreased with the SiO₂ content increased.Same content and different types of inorganic nano-SiO₂, Al₂O₃ and TiO₂ particles were added into organic precursor of PU-EP, then prepared the SiO₂/PU-EP, Al₂O₃/PU-EP and TiO₂/PU-EP nanocomposites. The mechanical properties and thermal stability of nanocomposites were investigated by electronic tensile machine, TGA. The results showed that the mechanical property and thermal stability of the Al₂O₃/PU-EP composite was the best when the adding amount of the nano-Al₂O₃ is 2wt%.