Processing and characterising photo-sensitive polymer in the rapid prototyping process

Abstract

The curability of an acrylic-based photo-polymer used in building rapid prototypes has been studied. Differential scanning calorimeter (DSC) was used to monitor the degree of curing after laser scanning. Rapid prototypes formed using the Stereolithography (SL) method have to undergo post-curing for increasing their strength and rigidity. This study attempts to reduce, if not eliminate, post-cure distortion by characterising curing behaviours. The curing characteristics of the photo-polymer at the micro-level were studied using Raman spectrum analysis. Specimens of single photo-polymer lines were created using a SL machine. Raman spectroscopy was used to quantify the curing percentage at different areas on the cross-section of these lines. Curing percentage before and after post-curing were also obtained from the experiments for analysis. The difference in the percentage of post curing gives an indication to the distortions faced. It was found that uncured and partially cured resins trapped within the photo-polymer resulted in in-homogeneity of curing in the specimens, causing shrinkage and distortion.