Thermal and Flame Resistant Properties of Poly (Lactic Acid)/Poly (Methyl Methacrylate) Blends Containing Halogen-free Flame Retardant

AbstractFlame retarded poly(lactic acid)/poly(methyl methacrylate) (PLA/PMMA) blend was prepared using melt compounding technique in the presence of isopropylated triaryl phosphate ester flame retardant [FR; 20 parts per hundred resins (phr)]. The effect of FR on the thermal and flame resistant properties of PLA/PMMA blend was studied. The flammability of PLA/PMMA blends was evaluated by UL-94 vertical burning test while the morphology of the residues was analyzed using field emission scanning electron microscope (FESEM). Thermogravimetric analyzer (TGA) was utilized to characterize the thermal decomposition behaviors of PLA/PMMA blends. The UL-94 result revealed that the inclusion of FR has shorten the after-flame time and improved dripping behavior of PLA/PMMA blend, achieving V-0 ranking in the test. An extensive and continuous carbonaceous char-like layer was found on the surface of the PLA/PMMA/FR residue, indicating the existence of condensed phase mechanism by FR. The incorporation of FR has accelerated the thermal degradation of PLA/PMMA blend at low temperature, but enhanced thermal stability of the blend at elevated temperature