Biobased Acrylate Composites with Enhanced Strength for Additive Manufacturing

With the expanding use of polymers in additive manufacturing, sustainable resins for use in vat photopolymerization are required to reduce their environmental impact. One promising approach to achieve this is to incorporate biobased fillers that replace the acrylates in photopolymer resins as 'green' alternatives. In this study, photopolymer composites consisting of a methacrylate resin with varying calcium carbonate powder content between 0 and 50 wt.% were investigated. A digital light processing technique was used to fabricate tensile test specimens for mechanical testing. Good printability, dimensional accuracy, and good interlayer adhesion were observed for composite resin formulations that incorporated calcium carbonate up to 50 wt.%. Green parts were subsequently washed and exposed to ultraviolet radiation at various post-cure temperatures between 20 and 80 degrees C. Specimens were tested on an Instron universal testing machine to evaluate stress-strain characteristics, which included Young's modulus, ultimate tensile strength, yield strength at 0.2% offset, resilience, toughness, and percent elongation at break. Elevated calcium carbonate content and higher post-cure temperatures demonstrated higher Young's modulus values, reaching 4297 MPa for 50 wt.% calcium carbonate at a post-cured temperature of 80 degrees C, indicating increased stiffness and resistance to elastic deformation under load for the compositions with increased biobased filler content. The ultimate tensile strength of the composite resin formulations was higher when exposed to elevated curing temperatures and remained between 22 and 32 MPa for all concentrations of calcium carbonate. The biobased composites evaluated in this study demonstrated that the modification of acrylate resins with biobased filler powders such as calcium carbonate is a feasible approach to sustainably enhance the mechanical properties of polymeric materials for additive manufacturing.