2-Dimensional strain mapping and post curing effects on viscoelastic properties of glass fiber infused photocurable composites prepared using Vat-photopolymerization process

Purpose The purpose of this study is to explore the effect of different post-curing times on the mechanical properties, specifically the visco-elastic characteristics, Poisson’s ratio and modulus, of three dimensional (3D) printed photopolymer composites (PPCs) reinforced with short glass fibres (SGF). Design/methodology/approach This research uses digital light processing-based Vat-photopolymerization process to 3D print PPCs reinforced with SGF at volume fractions of 2%, 4%, 6% and 8%. An inter-stage stirring process was used to reinforce the SGFs in a layer wise fashion. After printing, the parts undergo post-curing for 20, 60 and 100 min. The mechanical properties are then analyzed using dynamic mechanical analysis and in situ optical measurements. In addition, two-dimensional strain mapping from digital image correlation techniques is used to assess the structural behavior. Findings This study found that composites with 4% SGF reinforcement achieved the highest storage modulus, approximately 1,550 MPa, after 60 and 100 min of post-curing. In addition, the Poisson’s ratio of these composites increased from 0.2 to 0.41 with rising temperature. By applying Poisson’s ratio correction, the modulus was observed to be 1,800 MPa. These results indicate that optimal SGF content and post-curing times significantly enhance the mechanical properties of 3D-printed PPCs. Originality/value This research uniquely combines the reinforcement of photopolymers with SGFs at varying volume fractions and the detailed analysis of post-curing times to enhance the mechanical properties of 3D printed PPCs.