Preparation and Properties of PLA / GF / PBAT Composites for Investment Casting via Selective Laser Sintering

ABSTRACT Investment casting (IC), a precision casting technology, is plagued by toxic and harmful gas emissions (e.g., PAHs) when polystyrene (PS)‐based molds are fabricated via selective laser sintering (SLS). To address this issue with eco‐friendly alternatives, biodegradable polylactic acid (PLA) was adopted as the matrix, reinforced with glass fiber (GF) and toughened with poly (butylene adipate‐co‐terephthalate) (PBAT) for performance enhancement, thus expanding its applicability in IC molds. PLA/GF/PBAT composites were prepared by physical blending and SLS, followed by systematic characterization of their thermal, mechanical, heat‐resistant, and micromorphological properties as well as micromorphology. Results show that GF acts as a heterogeneous nucleating agent to accelerate PLA crystallization, narrow and downshift the cold crystallization peak, and improve crystalline perfection. The synergistic incorporation of GF and PBAT elevates the composite's Vicat softening temperature from 60°C (pure PLA) to ~120°C, significantly enhancing mold dimensional stability during IC heating. Moderate GF/PBAT addition facilitates the formation of dense, well‐bonded sintered microstructures, whereas excessive addition induces pores and weak interfacial bonding. With optimal filler contents, the “rigid reinforcement‐flexible toughening” synergy is realized, raising the composite's flexural strength to ~6.0 MPa and effectively ameliorating PLA brittleness.