While metal-organic frameworks (MOFs) hold great promise for a wide range of industrial applications, the challenges of handling fine crystalline powders have limited their adoption. MOF-polymer composites are one solution to this challenge, as composites or membranes are substantially easier to handle, however most existing MOF-polymer composites have low MOF loadings and suffer MOF leaching due to the weak interactions between the MOF and the polymer. In this work, we report the continuous extrusion of MOF-polymer composites containing up to 60 wt% of commercially available MOFs and successful extrusion of small amounts composites containing 70 wt% MOF, with the composite viscosity an important factor in the success of the extrusion. The MOF is well-distributed through the composite and remains crystalline despite the high temperatures and mechanical forces involved in the extrusion process. While the composites are more brittle than the base polymer and appear largely non-porous, the suspected presence of inaccessible internal pores coupled with the increased thermal stability of the composites compared to the base polymer indicate potential for the composites to be used as fire resistant materials.

Polylactic acid (PLA) is a biodegradable polymer with good processability, but its poor flame retardancy limits its wider practical use. In this work, an ethanol-assisted pre-assembled g-C₃N₄/fumed silica hybrid (gCNFS) was introduced into a PLA/ammonium polyphosphate (APP)/lignin system to improve its flame-retardant performance. The pre-assembly strategy was designed to improve the interfacial contact between g-C₃N₄ and fumed silica and regulate char formation and thermal decomposition during burning. The chemical structure and morphology of the composites were analyzed to study their thermal degradation behavior, volatile release, and post-burn char morphology. The results showed that the introduction of pre-assembled gCNFS improved the flame retardancy of the PLA/APP/lignin system. Among all formulations, PLA/Q-gCNFS-3 exhibited the best overall performance, achieving a limiting oxygen index (LOI) of 37% and a UL-94 V-0 rating. Compared with neat PLA, its peak heat release rate (pHRR) and total heat release (THR) decreased by approximately 50% and 24%, respectively, indicating effective suppression of burning intensity and total heat output. The flame-retardant mechanism of PLA/APP/Lignin with gCNFS enhanced both condensed-phase and gas-phase flame-retardant actions. In the condensed phase, a continuous and compact expanded char layer with better sealing ability and barrier performance was formed. In the gas phase, nonflammable gas release occurred, which helped reduce the concentration of combustible volatiles. Hence, the ethanol-assisted pre-assembled gCNFS is an effective strategy for improving the flame-retardant efficiency of PLA/APP/lignin composites.