Effect Of Organic Modifiers On Structure And Properties Of Epoxy Resin-Based Nanocomposites

In recent years,polymer-based nanocomposites have been widely concerned by academics and industry all over the world,and have become a new way to realize the high performance of general-purpose polymers.There are two key factors to improve polymer performance by adding nanofillers(nanoclays,nanocrystalline diamonds,graphene,etc.):First,nanofillers are uniformly dispersed in the polymer matrix;second,polymer matrix and nanofillers can build an appropriate strength between the interface force.However,the nanofillers tend to agglomerate in the polymer matrix,which in turn leads to the deterioration of the material properties.Appropriate use of organic modifiers to modify the nano-filler and take a special material preparation process is an effective means to solve these two problems.In this paper,epoxy resin(EP)as the matrix,different kinds of organic modifiers were used to modify various nano-fillers to prepare organic nano-fillers with different properties,and then different interfacial forces were built between the EP matrix and nano-fillers.The use of this new preparation process"slurry compound"to achieve good dispersion of nano-filler in the epoxy matrix.Based on this,the influence of the interfacial forces on the thermal/mechanical properties of epoxy resin-based nanocomposites was investigated systematically.The main findings are as follows:1.Two types of organoclay,D230-Clay and D600-Clay,were obtained by modifying the clay with single-ended amine protonated polyetheramine(Jeffamine D230)and protonated polyetheramine Jeffamine D600.A bisphenol A epoxy resin(E51)/butanediol glycidyl ether(BDGE)mixture as a matrix material,two kinds of flexible epoxy/clay nanocomposites with almost the same peel structure were synthesized by"clay-ethanol slurry composite method".The results show that the glass transition temperature(T_g)of both organoclay modified epoxy resins is much higher than that of pure flexible epoxy resin.When the mass fraction of clay is 3%,the T_g of D230-Clay modified epoxy resin is increased by 87.89%and the T_g of D600-Clay modified epoxy resin is increased by 46.51%.When the mass fraction of clay is 3.5%,the tensile strength of D230-Clay modified epoxy resin is increased by 3.6 times,the tensile modulus is increased by 2.19times and the elongation at break is increased by 11.65%;The D600-Clay modified epoxy resin tensile strength is increased by 3.04 times and the tensile modulus by 1.83 times,elongation at break increased by 19.65%.It is indicated that the addition of these two types of organoclay makes the strength,modulus and toughness of flexible epoxy resin increase synchronously.In comparison,D230-Clay is more effective than D600-Clay in improving the mechanical properties of epoxy resin.This is attributed to the fact that the amino group remaining on the D230-Clay can participate in the curing reaction of the epoxy resin,thereby forming a strong interfacial force between the clay layer and the epoxy resin matrix through the chemical bond.However,the D600-Clay Only a hydrogen bond between the resin matrix force.2.Dopamine clay was used to prepare dopamine intercalation clay(D-Clay)to modify EP.EP/D-Clay nanocomposites were prepared by clay-ethanol slurry composite method,and D-Clay was well dispersed in epoxy resin.The results show that epoxy resin/D-Clay nanocomposites have significantly increased in T_g and mechanical properties(such as tensile strength,tensile modulus,and hardness)compared to pure epoxy resins.When the mass fraction of D-Clay was 3%,the T_g increased by 10.09?,the tensile strength increased by 29.34%,the tensile modulus increased by23.19%.When the mass fraction of D-Clay was 4%,the hardness increased by 53.87%and the thermal decomposition temperature increased by 25?.The hydroxyl groups carried on the surface of D-Clay can form hydrogen bonds with the EP matrix to form strong interfacial forces and the uniform dispersion of the clay layer in the EP matrix,which makes the thermal and mechanical properties of the EP/D-Clay nanocomposites.significantly improved performance.This work has provided a new type of filler(D-Clay)for the preparation of various polymer-based nanocomposites with good thermal/mechanical properties.3.Dopamine-coated nano-diamond(D-ND)was prepared by the modification of nano-diamond(ND)with dopamine hydrochloride and the EP/D-ND nano-composite with D-ND uniformly dispersed was successfully prepared by slurry method.The results show that:the D-ND modified EP,the overall performance was significantly superior to pure EP.When the mass fraction of D-ND was3%,the tensile strength of the composites increased by 12.22%,the tensile modulus increased by19.57%and the elongation increased by 38.37%.Thermal decomposition temperature increased by26?,hardness increased by 25.15%.The composites with 3.1 wt%D-ND have the best tribological properties,the friction coefficient is reduced by 11.36%,the wear scar depth is reduced by 20.93%and the wear rate is reduced by 37.67%.These properties are attributed to the presence of hydroxyl groups on the surface of D-ND and hydrogen bonding with the EP matrix to create a stronger interfacial interaction between the EP matrix and D-ND,thereby rendering EP/D-ND nanocomposites more excellent performance.