Effects Of Functionalized Graphene Sheet Size On Curing Kinetics And Mechanical Properties Of Epoxy Resin Composites

Epoxy matrix composites are widely used in high-voltage transmission cables,sports equipment,automobile production,aerospace and other fields because of their high tensile strength,good dielectric properties,thermal stability and corrosion resistance.In order to improve the modulus,toughness and interfacial bonding ability of the epoxy matrix,the functionalized graphene oxide modified epoxy matrix has been a research hotspot in recent years.However,the difference size of the graphene oxide will change their physical and chemical properties,which in turn affect the thermal conduction,mechanics and curing behavior of composite materials.In this paper,through the design of graphene oxide sheet size and surface function groups,the dispersibility of different sizes of amino-functionalized graphene oxide in epoxy resin and its effect on epoxy resin curing kinetics and mechanical properties were investigated.In this paper,two kinds of graphene oxides with different size and narrow distribution are prepared by using two kinds of graphite flakes with different meshes and different tip sonication time.Secondly,triethylenetetramine(TETA)and diethyltoluenediamine(DETDA)were grafted onto the surface of graphene oxide.TETA grafted large and small sheet graphene oxide(L-TETA,S-TETA)and DETDA grafted large and small sheet graphene oxide(L-DETDA,S-DETDA)were prepared.The effects of L-TETA,S-TETA,L-DETDA and S-DETDA on the curing kinetics of bisphenol A epoxy resin(DGEBA/DETDA)were analyzed by isothermal and non-isothermal kinetics.The Kissinger-Akahira-Sunose(KAS)method revealed the change trend of the activation energy of the DGEBA/DETDA system during the reaction after different graphene oxides were added.Then the curing mechanism function of different systems was obtained by the model fitting method proposed by Malek.The Kamal autocatalytic reaction model revealed the effect of adding different graphene oxides on non-autocatalytic and autocatalytic reactions in the curing reaction.Two types of amino-functionalized graphene oxide/epoxy resin nanocomposites were prepared by dispersing L-DETDA and S-DETDA in DGEBA/DETDA epoxy resin matrix.The results show that when the amount of L-DETDA added is 0.1 wt%,the bending strength and modulus reach the maximum,increasing by 23.4%and 32.4%,respectively.When the amount of S-DETDA added was 0.2 wt%,the bending strength and modulus reached the maximum,which were increased by 37.2%and 10.5%,respectively.At the same time,the amino-functionalized graphene oxide/T700/epoxy unidirectional composite materials and micro-debonding samples were prepared.The results show that the enhanced effect of S-DETDA is more excellent,when the amount of S-DETDA added was 0.2 wt%,the flexural strength,interlaminar shear strength and interface shear strength of the epoxy composite are increased by 15.2%,14.1%and 54.8%,respectively.