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A cross-linking strategy with moderated pre-polymerization of resin for stereolithography
- Ni, Rongping, Qian, Bin, Liu, Chang, Liu, Xiaofeng, Qiu, Jianrong
- RSC advances 2018 v.8 no.52 pp. 29583-29588
- adjuvants, compression molding, crosslinking, ethylene glycol, hardness, mechanical properties, poly(vinyl chloride), polyethylene glycol, resins, shrinkage, slurries, viscosity
- Compared with parts fabricated via traditional methods, such as injection or compression molding, polymeric parts produced by 3D stereolithography (SLA) have poorer mechanical properties. Here, we demonstrate a cross-linking strategy used in the coating field to attain long chains for resin pre-polymerization to obtain final resin parts which can expand the application of SLA. Isophorone diisocyanate (IPDI), 2-hydroxyethyl methacrylate (HEMA) and polyethylene glycol (PEG)-based prepolymer have long chains, making it easier for them to form dense structures. However, the prepolymer has high viscosity and can solidify in the absence of a laser. Thus, three kinds of adjuvants were added to dilute the prepolymer to make the slurry suitable for 3D-printing. Slurries were cured with different laser powers and scanning speeds. Diluents are found to affect the curing properties differently. With the diluent 2-hydroxyethyl acrylate added into the prepolymer, shrinkage of printed parts is lower than 1.3%. With the diluent ethylene glycol monophenyl ether, the density range of printed parts is between 1.187 g cm⁻³ and 1.195 g cm⁻³, which is higher than that of commercial PVC and PET. The three resins vary in density and hardness within a small range when the scanning speeds change. A relatively flat surface, high density and hardness can be obtained when the laser power is at 195.5–350 mW. Resin with this cross-linking strategy can expand the underutilized stereolithography's application from prototyping to actual parts by producing more functional components with excellent performance.