Study of shrinkage strains in a stereolithography cured acrylic photopolymer resin

The shrinkage characteristics of stereolithography (SL) built square laminate plates using an acrylic-based photopolymer were studied after they had been post-cured under ultraviolet and thermal exposure. The specimen plates consisted of a resin layer laser cured on an identical layer of the same material that had already been cured and post-cured. The assembled laminate was then cured, and the resulting out-of-plane displacement (warpage) due to shrinkage was recorded by means of the shadow moiré method. The exhibited warpage of the plates was related to the polymerisation shrinkage strains through the elastic lamination theory, which was implemented to calculate the magnitude of the resulting shrinkage strains. It was obtained that the acrylic-based resin plates exhibited considerable warpage, while thermal post-curing resulted to higher shrinkage in the y-axis of the plates.