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

Abstract

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.

Modification of photosensitive resin with fumed silica

“…As the most basic curing molding material in photocurable 3D printing [13], photosensitive resin is one of the main consumables for photocurable 3D printing. Photosensitive resin is a kind of polymer colloidal substance that changes its chemical structure when exposed to light [14].…”

3D printed objects obtained by combination of radical photopolymerization and photo sol–gel reaction: towards reinforced thermomechanical properties

“…4,5 Combination of radical and cationic photopolymerization [6][7][8] is an interesting alternative to overcome these limitations. Besides compensating the shrinkage by volumetric expansion due to the ring-opening polymerization of (spiro/)epoxy compounds, [9][10][11] the living character 12 of this reaction improves interlayer adhesion. 13,14 However, the difference between the reactivity of acrylate and epoxy mono-mers can be linked to insufficient mechanical properties as long as epoxy polymerization is not sufficiently advanced.…”