, Timothy C. Mauldin, , , Dylan B. Timothy
A new isosorbide-based polyphosphate was synthesized and applied as a flame-retardant for polylactic acid (PLA). The storage modulus and glass transition temperature of PLA is unaffected by the inclusion of polyphosphonate, but moderate depressions of PLAs tensile strength (16 %, 28 %, and 45 % reduction from PLA at a polyphosphonate mass fraction of 5 %, 10 %, and 15 %, respectively) and strain-at-break (0 %, 17 %, and 30 % reduction from PLA at a polyphosphonate mass fraction of 5 %, 10 %, and 15 %, respectively) were observed. UL 94 flammability testing indicated that isosorbide- based polyphosphonates are effective flame retardants for PLA that are able to self-extinguish flames in less than 2 s and achieve V2 and V0 ratings at polyphosphonate mass fraction of 5 % and 15 %, respectively. Mechanisms for isosorbide-based polyphosphonate flame retardancy are discussed. Use of the biobased flame retardants described herein yields flame retardant PLA containing up to 97 % by mass of bio-derived content.
Polylactid acid, biobased, flame retardants