Formulation and Study of New Eco-Friendly Intumescent Polylactic Acid Based Materials

Polylactic acid (PLA) is a biodegradable and bio-based polymer obtained by polymerization of lactide or lactic acid, both arising from renewable resources like cereals’ starch. Polylactic acid is also a semycristalline thermoplastic polymer and has mechanical properties in between polystyrene and polyethylene terephthalate. In the last decades the interest on this polymer raised very fast and its industrial production increases very rapidly, in the same way the number of published researches have exponentially increased. Nowadays the main PLA applications consist on food packaging, disposable tableware, biomedical items and textiles. Future and new PLA applications are focusing towards electric, electronics, and transport field. The materials for this kind of applications must have good flame resistance properties and several flame and burning tests must be passed before these materials can be applied. PLA does not have flame resistance properties and burn in air in case of a fire source. Focusing my research to solve this issue, PLA based materials with different flame retardants additives have been formulated and tested. Intumescence has been studied as mechanism to achieve good flame resistance properties, and halogen-free, non-toxic and eco-friendly additives have been used trying to maintain the material biodegradability. New eco-friendly intumescent polylactic acid based materials have been developed, using low load of halogen-free, not toxic and biodegradable additives (6, 10 and 14%). Bio-based and biodegradable carbonizing agents such as starch, sorbitol, coffee grounds, glycerol phosphate, cellulose and Kraft lignin have been tested (2%), and V-0 UL94 classification, LOI values over 32% and GWIT over 775°C were archived in presence of different amount of ammonium polyphosphate (4, 8.5%) for all the carbonizing tested. The presence of zinc borate increased the flame resistance of the materials yielding the lowest total heat release in synergy among all carbonizing agents tested.