Polylactic acid (PLA) is a biodegradable thermoplastic polymer which can be produced from bio-resources (crops and plant by-products), but it is highly flammable and can cause fire spread by flaming drips. Different PIN flame retardant solutions are proposed for PLA (pinfa Newsletters 29, 50). A new study assesses bio-sourced polymeric phosphorus PIN FRs, based on cellulose, and the bio-material and mineral-based PIN aluminium phytate.
Microcrystalline cellulose MCC (obtained by partial depolymerisation of plant cellulose) and natural nanocrystalline cellulose NCC (extracted from ramie fibres = China grass) were tested. PLA / cellulose fibre composites (20 or 30% fibres) achieved UL94-V0 and reduced pHRR (peak heat release rate) using these PIN FR solutions. The nanocrystalline cellulose achieved target fire performance more easily because its high specific surface area enabled better char formation.
“Cellulose/phosphorus combinations for sustainable fire retarded polylactide”, Eur. Polymer Journal 74 (2016) 218–228, L. Costes et al., University of Mons, Belgium.