Polymer Property Enhancements of Poly(Lactic Acid) using POSS-Modified Cellulose Based Intumescing Flame Retardants

摘要

Intumescing flame retardants (IFRs) are a relatively new class of additives for improving the flammability properties of polymers and polymer composites. These additives consist of (a) an acid source, (b) a carbon source, and (c) a gas forming source. They have received significant attention because of their ability to produce a heat and fuel char barrier with little smoke and without the use of halogens. Like many other flame retardants, they require a relatively high loading (15 % to 25 % by mass) to successfully pass fire tests, such as limiting oxygen index and UL-94 vertical burn. As a result, the composites suffer significant losses in mechanical strength and melt viscosity. Furthermore, the components are often water soluble, leading to leaching of the additives, conversion of often used ammonium polyphosphate to phosphoric acid, and a loss in flame resistance upon exposure to moisture. This can also lead to decomposition of moisture sensitive polymers, such as poly(lactic acid), during compounding. Finally, the lower thermal stability of the components than many high performance polymers, such as polyamides or poly(ethylene terephthalate), preclude their use in these systems.