Study On The Low Shrinkage And High Strength Epoxy Acrylate Based UV-curing 3D Printing Materials

Building materials are the most critical materials in UV-curing 3D printing.Their properties directly affect the quality of final parts.Because of the special process of UV-curing 3D printing,the disadvantages of the building materials which can be used for UV-curing 3D printing include high curing shrinkage and poor mechanical properties etc.In this paper,a kind of epoxy acrylate(EA)based UV-curing 3D printing building materials low shrinkage was prepared by self synthesis hyperbranched polyester acrylate(L-HBP)as building materials repolymer and then using graphene oxide(GO)to enhance its modification.Finally,a low shrinkage,high strength EA based UV-curing 3D printing building materials was obtained.Firstly,the hyperbranched polymers L-HBP was synthesized and the optimum synthesizing conditions was determined,then the curing properties and injection properties of L-HBP were studied.The results showed that L-HBP may induce UV polymerization and the curing volume shrinkage rate of L-HBP UV-curing specimen(the ratio of L-HBP to active monomer was 8:2)was 2.86%.The viscosity and surface tension of L-HBP at 60? were 151.33mPa·s and 29.10mN/m,respectively.It was proved that L-HBP possessed good curing properties and injection properties,which could be used as prepolymer to prepare low shrinkage EA UV-curing 3D printing building materials.L-HBP and EA with good mechanical properties were used as prepolymer of the building materials.The effects of weight content of each component on the curing volume shrinkage rate,viscosity,curing speed and others properties of the building materials were studied.The research showed that L-HBP with low viscosity was used as prepolymer,which could significantly reduce the content of small molecular active monomer in the building materials,so that the concentration of C=C double bonds in the building materials decreased,and the volume shrinkage of the cured materials decreased accordingly.When 40wt% L-HBP was added,building materials possessed the best comprehensive property,and the curing volume shrinkage rate was 3.97%,which was reduced by 45.48% compared with the building materials prepared only by using EA as prepolymer.The surface of GO was grafted by polymethyl methacrylate(PMMA),obtaining GO-g-PMMA which was used to enhance for low shrinkage EA based UV-curing 3D printing building materials.The GO treated by PMMA could be dispersed uniformly in the building materials,and with the building materials between the formation of chemical cross-linking point made the interaction between the chain and the chain was enhanced,adding appropriate amount of GO-g-PMMA was able to obviously improve the mechanical properties of the building materials.When 0.1wt% GO-g-PMMA was added,the tensile strength,flexural strength and impact strength of the cured materials reached the maximum,which were 32.87 MPa,51.29 MPa and 10.70kJ/m2,respectively,compared with the unmodified building materials,they were improved by 49.47%,66.91% and 56.89%,respectively.