Microcellular foams were produced using the bio-sourced polymer PLA (poly lactic acid) and UL94-V0 fire performance achieved using a nitrogen, phosphorus and graphene (nano carbon plate polymer) based PIN flame retardant system. PLA is a bio-sourced polymer with increasing applications, particularly in markets for “green” and biodegradable packing and films, but it is inherently highly flammable. Here, PLA microcellular foams were produced using 4 MPa pressure, CO2 and water bath foaming.
The PIN flame retardant 100D (Starbetter, China), containing 21%N and 23%P was tested at 5 – 30% dosing in the PLA and graphene at 0.5 – 1.5%. Even at 5%, the PIN FR PLA foam achieved UL94 V-0 fire performance, with higher PIN FR loadings leading to increased foam expansion. The addition of graphene improved anti-dripping and reduced foaming, so resulting in more uniform foam cell structure
“Preparation of microcellular poly(lactic acid) composites foams with improved flame retardancy”, K. Wang et al., Journal of Cellular Plastics, 2016, http://dx.doi.org/10.1177/0021955X16633644