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Synergistic flame-retardant coating for enhanced PLA performance
New research introduces a novel flame-retardant system using DOPO-based polyamide and modified layered double hydroxides, achieving improved safety and mechanical performance for polylactic acid (PLA).
Recent developments in flame-retardant coatings have demonstrated significant improvements in the safety and performance of polylactic acid (PLA). Researchers have combined a DOPO-containing polyamide (DPA) with phytic acid/polyethylene imine-modified layered double hydroxides (MLDH) to create a synergistic system that enhances flame retardancy, thermal stability, and mechanical properties of PLA. Two modification strategies were employed: bulk reinforcement of PLA with MLDH and surface dip-coating using DPA and DPA/MLDH nanocomposites.
The study showcased the uniform dispersion of MLDH and effective coating formation through advanced analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field-emission scanning electron microscopy (FE-SEM). These analyses revealed improved interfacial interactions in the nanocomposite structure. Moreover, thermogravimetric analysis (TGA) confirmed enhanced thermal stability, with increased T10 values and char residue, effectively inhibiting flame propagation.
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Improved Flame Retardancy and Mechanical Properties
The flame-retardant properties of PLA were significantly enhanced by the dual-modification approach. The limiting oxygen index (LOI) was improved, and the peak heat release rate (pHRR) decreased by 35 %, compared to unmodified PLA. Furthermore, the system achieved a UL94 V-0 classification, demonstrating its potential for high-performance applications requiring stringent fire safety standards.
Mechanical testing further revealed substantial improvements in tensile strength, with values reaching up to 77.2 MPa, highlighting the reinforcing effect of MLDH within the PLA matrix. The research presents promising advancements for industries relying on PLA, such as packaging, automotive, and construction, where enhanced safety and durability are critical.
Source: Hajibeygi, M. & Heydari, M. Enhanced flame retardancy and thermal stability of PLA via DOPO-based polyamide and phytic acid/PEI-modified Ca-Al LDH: A synergistic approach through bulk and coating strategies. Prog. Org. Coat. 175, 109650 (2025).
