ABSTRACT The inherent flammability of polylactic acid (PLA) restricts its use in applications requiring both transparency and high fire safety, such as electronics and automotive interiors. This study demonstrates that a halogen‐free, solid phosphate ester FR can be used to formulate a transparent PLA compound that successfully meets stringent industry standards while preserving key physical characteristics. The compound, containing 15 wt% of the phosphate ester (PLA FR 15), achieved a UL‐94 V‐0 rating and a glow‐wire flammability index (GWFI) of 960°C at thicknesses of 1.6 and 3.2 mm, with effective suppression of flaming melt dripping. Optical transparency was largely maintained, as confirmed by UV–vis spectroscopy showing transmittance nearly identical to neat PLA. The additive also functioned as a multifunctional agent, enhancing melt processability, exhibiting a moderate decrease in tensile strength and elongation at break, and maintaining impact strength without increasing density. Thermogravimetric analysis indicated a slight increase in thermal stability, with the onset degradation temperature rising from 345°C to 355°C. The results indicate that this specific phosphate ester provides a balanced solution to the classic conflict between flame‐retardancy, transparency, and mechanical performance in PLA.
Karaca et al. (Thu,) studied this question.