Quasi-ductile to brittle transitional behavior and material properties gradient for additively manufactured SLA acrylate

Abstract

• Quasi-ductile to brittle transitional behavior investigation of SLA acrylate. • Low curing energy leads to a ductile behavior and clean fracture surface. • High curing energy promotes a brittle behavior and rough fracture surface. • UV-curing creates a thickness-dependent material properties gradient. • Strain rate sensitivity is both a curing- and thickness-dependent variable. This research investigates the correlation between post-curing conditions, thickness, stress–strain, and fracture behaviors of additively manufactured SLA acrylate polymer, utilizing tensile tests and scanning electron microscopic fractography analysis. Due to poor polymerization, low curing energy resulted in a quasi-ductile behavior and low strain rate sensitivity. In contrast, high energy promotes the redistribution of the fracture energy from failure strain to failure stress, leading to increased sensitivity. Furthermore, poorly cured specimens show clean fracture surfaces, contrasting with their quasi-ductile behavior, whereas highly cured specimens present rough surfaces, generally associated with ductile fracture. Therefore, increasing curing energy promotes a transition from a quasi-ductile to an almost perfectly brittle behavior and influences the material's elastic, plastic, and fracture behaviors, which appear to be non-uniform throughout the thickness, especially for thicker structures.