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

The curability of an acrylic-based photo-polymer used in building rapid pro totypes has been studied. Differential scanning calorimeter (DSC) was used to monitor the degree of curing after laser scanning. Rapid prototypes form ed using the Stereolithography (SL) method have to undergo post-curing for increasing their strength and rigidity. This study attempts to reduce, if n ot eliminate, post-cure distortion by characterising curing behaviours. The curing characteristics of the photo-polymer at the micro-level were studie d using Raman spectrum analysis. Specimens of single photo-polymer lines we re created using a SL machine. Raman spectroscopy was used to quantify the curing percentage at different areas on the cross-section of these lines. C uring percentages before and after post-curing were also obtained from the experiments for analysis. The difference in the percentage of post curing g ives an indication to the distortions faced. It was found that uncured and partially cured resins trapped within the photo-polymer resulted in in-homo geneity of curing in the specimens, causing shrinkage and distortion. (C) 1 999 Elsevier Science S.A. All rights reserved.