Polylactide (or poly lactic acid PLA) is a biodegradable polymer which can be sourced from agricultural by-products, see pinfa Newsletter n°50. However, a challenge for PLA use in many applications is to ensure fire safety, because the polymer is highly flammable and poses important melt dripping challenges.
In this study, a cross-linked silicone-containing macromolecule (CSi-MCA), synthesised in a one-step reaction, was tested with ammonium polyphosphate (APP). APP is a PIN flame retardant recognised to offer high levels of health and environmental safety (see e.g. pinfa Newsletter n°74). A loading of 5% w/w CSi-MCA and 10% w/w APP in polylactic acid showed production of a compact and continuous protective char layer during combustion, with peak heat release rate reduced by more than 50% compared to straight PLA, and achieved UL94-V0 at 3mm.
““One-pot” synthesis of crosslinked silicone containing macromolecular charring agent and its synergistic flame retardant poly(L-lactic acid) with ammonium polyphosphate”, Y. Guan et al., Polymers Advanced Technology 2017 http://dx.doi.org/10.1002/pat.4017