Study On The Effect Of Block Copolymer Modified Graphene Oxide On The Properties Of Epoxy Resin And Its Carbon Fiber Composites

As an important thermosetting resin,epoxy resin has excellent physical and mechanical properties,electrical insulation,chemical resistance,heat and adhesive properties and excellent moulding process.As a result,they are widely used in the fields of electronics,machinery,chemicals and aerospace.Among them,epoxy resin,as one of the most important high performance composite matrix resins,has extremely important application value in the aerospace field.However,the three-dimensional cross-linked network structure of epoxy resins after curing substantially restricts the movement of epoxy molecular chains,resulting in brittle cured products,poor impact toughness and low stress cracking resistance.At present,many researchers are trying to add appropriate nano fillers to overcome the brittleness and improve the fracture toughness of epoxy composites.Block copolymers are often added to epoxy composites as toughening agents,but their modulus and strength are often sacrificed to improve toughness.Meanwhile,graphene oxide,a novel two-dimensional sheet-like carbon nanomaterial,has extremely high fracture strength and Young's modulus,and is therefore considered an ideal reinforcement for the preparation of polymer-based nanocomposites.Therefore,inspired by the strengthening effect of nanoparticles and the toughening effect of block polymers,a block polymer filler based on GO was prepared by surface initiated atom transfer radical polymerization(SI-ATRP).In the side group of the main molecular chain segment of the block polymer,glycidyl methacrylate(GMA)fragment and N-(3,4-bis(tert-butyldimethylsilyl)oxy)phenyl ethyl)methyl acrylamide(DOPAm _TBDMS)fragment can promote dispersion and toughening,respectively.The molecular structure was characterized by FTIR and XPS.The thermo-mechanical properties,mechanical properties and toughening and strengthening mechanism of the epoxy composite(FGO-E51)with different proportions of modified GO were studied by comparing the epoxy composite(FGO-E51)with the epoxy composite(E51)without addition.The amount of modified GO was 0.1%,0.25%,0.5%and 0.75%,respectively.When the amount of modified GO was 0.25wt%,the bending strength reached 151MPa,which was37.27%higher than that of pure epoxy composite.The tensile strength and impact strength of cantilever beam were increased by 50.56%and 69.89%respectively.These were attributed to the strengthening and toughening of GO and its side groups.Then,the modified GO carbon fiber composite was prepared.The bending strength,tensile strength and interlayer shear strength of FGO-E51 carbon fiber composite were studied by comparing with E51 carbon fiber composite.The results showed that the mechanical properties of carbon fiber composites are significantly improved by adding modified GO.When the addition amount was 0.25%,the mechanical properties of carbon fiber composites reached the best.The tensile strength reached 2150MPa,increased by 36.9%;The bending strength reached1830MPa,increased by 39.7%.It was proved that the mechanical properties of epoxy and carbon fiber composites can be improved by adding modified go filler.