Effect of Cellulose Nanocrystals on Fire, Thermal and Mechanical Behavior of N,N′-Diallyl-phenylphosphoricdiamide Modified Poly(lactic acid)

Presented herein is a deep investigation of the fire, mechanical and thermal performances of poly(lactic acid) (PLA)-based nanocomposites, which were obtained by combining cellulose nanocrystals (CNC) with various contents of N, N'-diallyl-phenylphosphoricdiamide (P-AA) via a two-steps masterbatch melt extrusion process (glycidyl methacrylate grafting on PLA and CNC premixing with PLA). Results have shown that the value of the limiting oxygen index (LOI) increased to 28.8% and a V-0 rating in UL94 test was obtained when 2 wt% of P-AA was added in the presence of cellulose nanocrystals (3 wt%). The incorporation of CNC induced a decrease of both PHRR and THR values in micro combustion tests; meanwhile, the nucleating and plasticization effects of CNC and P-AA were evidenced. Results from tensile tests and dynamic mechanical thermal analysis (DMA) showed that the addition of CNC importantly enhanced the mechanical performance of P-AA containing systems, while the thermal stability of the nanocomposites was slightly improved in the presence of the cellulosic nanoreinforcement.