Flame retardant poly(lactic acid) biocomposites reinforced by recycled wool fibers – Thermal and mechanical properties

Abstract

The inherently poor flame retardancy and comparatively low tensile strength of poly(lactic acid) (PLA) have limited its wide adoption as alternative 'green' engineering plastic in many fields. This manuscript reports the synthesis of a new phosphorus flame retardant-phenylphosphonic 3(2-aminobenzothiazole) (P-TAB) and its combination with recycled short wool fibers (WF) for improving the flame retardancy and the mechanical properties of PLA. Fourier transform infrared (FTIR), 1 H, and 13 C nuclear magnetic resonance (NMR) spectra proved that P-TAB was effectively synthesized. Considerable reductions in heat release rate, total heat released, CO and CO 2 produced were attained with 3 wt% P-TAB and various WF loadings. The fire performance index (FPI), and fire growth index (FGI) improved by 38.2 and 48.1% respectively. The composite achieved a V-0 rating at 20 wt% WF loading and an LOI value of 28.5%. TG-IR results showed substantial reductions in evolved gaseous products. The tensile strength and Young's modulus improved significantly with the increasing content of WF in the composite.

Keratinous Natural Fibres as Sustainable Flame Retardants and Reinforcements in Polymer Composites

“…For modifying thermoplastic matrix DOPO derivatives, phosphorusnitrogen compounds, metallic oxides like aluminium hydroxide, and nano materials have been employed. Tawiah et al [104] developed a novel phosphorus FR Phenyl phosphonic 3(2-aminoben-zothiazole) (P-TAB) and added it to PLA using combinatory solvent mixing to enhance its flame retardancy and mechanical properties. They further incorporated varying percentages of recycled wool fibres, which aided in attaining a V0 rating in the UL-94 test.…”

Novel ranking framework for retrospective simultaneous assessment of fire and mechanical performances of natural fiber‐reinforced polymeric composites: Literature update from the previous decade

“…[ 32 ] Its microfibrillated cross‐linked structure results in high tensile strength. [ 33 ] When combined with thermoplastic polymer‐based composites, improvement in mechanical strength and flame resistance can be achieved. [ 34 ] Wool has higher intrinsic flame resistance than other NFs due to its considerably high nitrogen, sulfur and moisture content, low heat of combustion, high ignition temperature and high LOI.…”

Construction of crosslinking network structures by addingZnOandADRin intumescent flame retardantPLAcomposites

“…Results showed the mechanical properties and flame retardancy of the PLA composites increased. Microfibers and nano‐fillersFibers are effective filler to improve the mechanical properties of polymers. By adding fibers and flame retardant to PLA matrix, the mechanical and flame retardant properties can be improved in the meantime, for example, the recycled short wool fibers combine with the phenylphosphonic 3(2‐aminobenzothiazole) (P‐TAB), 45 the POSS‐modified nanofibrillated cellulose fibers (NFC) (PNFR), 46 porous submicron nickel oxide (NiO) fibers combined with nanosized CB, 47 the recycled bamboo chopstick fiber combined with APP and expandable graphite (EG) 38 . In addition, the fibers after modification were added into the PLA matrix as a flame retardant component in some literatures, which could effectively improve the comprehensive performance of PLA.…”