Comprehensive physicochemical evaluation of 3D-printed medical-grade poly(lactic acid)-based composite: Mechanical, thermal, and morphological properties

Abstract

Achieving a high mineral content has become a key focus in the design and additive manufacturing of 3D-printed biodegradable composite scaffolds to enhance biodegradation, osteoconductivity, and mechanical performance. However, the effects under simulated physiological conditions, such as temperature and hydration, which are important considerations from an implant design perspective, on these composites are not well understood. In this study, we employed medical-grade composite filaments consisting of 60% Lactoprene and 40% β-tricalcium phosphate (β-TCP) to 3D print scaffolds. We used various analytical techniques to characterize these scaffolds under simulated physiological conditions, including morphological, physicochemical, and thermomechanical analyses. The composite exhibited a glass transition temperature of 28°C, which significantly reduced its mechanical properties under physiological conditions. Interestingly, when gamma irradiation was used for sterilization, the compressive modulus increased by approximately 17 times, reaching 106.5 MPa. The composite also demonstrated notable recovery behavior, particularly in hydrated samples at 37°C, indicating hyperelastic characteristics. Our results highlight the importance of studying the hydration water in high-ceramic-content scaffold composites. We provided insights into the molecular interactions between ceramic materials, polymers, and water. This study underscores the necessity of testing composite scaffolds under physiological conditions and supports future research on the degradation behavior and in vivo testing of polymers reinforced with osteogenic fillers for scaffold-guided bone regeneration.