Controlling the distribution of fire retardants in poly(lactic acid) by fused filament fabrication in order to improve its fire behaviour

This study focused on the development of skin/core structures with flame-retarded poly (lactic acid) (PLA) compositions, by additive manufacturing. For this purpose, the technique of Fused Filament Fabrication (FFF) was chosen. Plate samples were also manufactured by injection moulding for comparison purpose. The nature of the flame retardants (FR), their contents and their distribution in the samples were varied. The fire behaviour was investigated by cone calorimeter tests. The microstructure was characterized and related to the fire performances of each flame-retarded PLA structure. The results showed a significant decrease of the time to ignition (TTI) of 3D printed samples compared to the injected ones, due to their higher porosity. However, for a given total FR content, concentrating FR close to the radiated surface proved to be a promising solution in order to optimize fire performance while preserving the mechanical properties of neat PLA. (C) 2019 Published by Elsevier Ltd.