Nano SiC ceramics and MOFs synergistically enhanced polylactic acid composites for efficient flame retardant performance

Abstract

Metal–organic frameworks (MOFs) are new hybrid materials with customizable three-dimensional structures, excellent stability, and tunable properties, making them promising for flame retardant applications. However, the multiple polar functional groups of the organic frameworks exhibit poor dispersion in the polymer matrix. Herein, alkali-etched silicon carbide nanoparticle (SiC_e)-functionalized MOFs were used to improve the dispersion ability of poly lactic acid (PLA) and eliminate its self-stacking and aggregation. Where the SiC/PLA, MOFs/PLA and SiC/MOFs/PLA polymers were investigated. By uniformly coating SiC_e/MOFs (PVP-modified HKUST-1 (HK_p)) onto the surface of PLA powder via the solution stir mixing method and hot-press molding process, a series of PLA composites were prepared, which displayed excellent mechanical and flame-retardant properties. When the SiC_e/HK_p content was 3%, the tensile strength and elongation at break increased by 37.3% and 30.3%, respectively. The pHRR of the composite was reduced by 33.9%, THR by 43.8%, and COPR and CO₂PR by 35.7% and 24.1%, respectively. The alkaline etching SiC method enabled the creation of toughened flame retardant composites based on MOFs by utilizing the 3D coupling effect of nano-SiC_e-functionalized MOFs. This design also ensured excellent dispersion of MOFs.