Effects of adding nano silica on hardness and tensile properties of stereolithography 3d printed parts

3D printing is one of the emerging technologies that can create any complex 3D objects by layer by layer printing approach. The purpose of the present study is to study the effects of adding silica nanoparticles to a methacrylate-based UV curable resin on hardness and physical and mechanical properties of the printed parts by projector-based stereolithography (DLP) ,due to it's higher resolution, higher speed and higher capabilities for industrialization. Silica was chosen as additive due to its ability to increase the physical and mechanical properties of the final parts as well as reducing the final price of printed parts. For this purpose, silica nanoparticles were added to the resin in 1, 3 and 5 wt. % with the help of the ultrasonic homogenizer. To investigate the physical and mechanical properties of the specimens, barcol hardness, tensile, FTIR and SEM tests were also performed. In this study, silica nanoparticles were added to the resin at three different weight percentages with the best results showing at 3 wt. % of nano-silica with 5.7% increases in tensile modulus respectively due to better distribution. Furthermore results showed the surface modification of silica nanoparticles enhanced the specimen’s strength further up to 8.8%. The surface hardness increase for the last layer of the samples containing 5% wt. silica nanoparticles in non-post cure state was 76% compared with the pure sample, and 16% after the post cure step (105 minutes). The results showed adding nanoparticles in order to increase hardness of the specimens is so effective.