Study on curing shrinkage and mechanism of DHOM-modified epoxy-acrylate-based UV-curing 3D printing materials

UV-curing 3D printing technology is one of the technologies with the highest molding efficiency and accuracy in the field of 3D printing. At present, the main problems of UV-curing 3D printing materials include the high curing shrinkage and the low toughness. In this work, free radical/cation hybrid curing system was developed, the effects of expansion monomer (DHOM, 3,9-diethyl-3′,9′-dihydro-xymethyl-1,5,7,11-tetraoxaspiro[5,5]undecanone) on the curing shrinkage, toughness, and other properties of the epoxy acrylate-based UV-curing 3D printing materials were investigated. The results showed that when the added amount of DHOM was 15 wt%, the best comprehensive performance of UV-curing 3D printing materials was obtained. At this time, the curing shrinkage rate decreased from 6.13% to 3.47%. The main reason was that DHOM undergoes ring-opening polymerization under the action of cationic photoinitiator, resulted in volume expansion. The impact strength increased from 9.61 to 12.13 KJ/m2, which was because that the ring-opening reaction of DHOM reduced the curing shrinkage of the resin system and released the internal stress between the resin molecules. © 2020 Wiley Periodicals LLC