Flame retardant polymeric materials for additive manufacturing

The occurrence of fire in a confined environment surrounded by polymeric components can lead to disastrous consequences. This makes it essential to consider flame-retardant polymers in critical applications, such as aircraft, automobile, and building interior designs. Conventional flame-retardant methods are dependent on either adding halogen or phosphorous based chemicals to achieve the required attributes. There are also polymeric options that are intrinsically fire-resistant and can satisfy the fire safety regulatory standards such as the UL94 or FAR 25.853. However, the window of options is quite narrow, considering other aspects such as the eco-friendliness, mechanical or chemical properties, and processing difficulties. On the other hand, additive manufacturing technologies are gaining ground in recent times, gradually making application potentials in both automotive and aerospace industries. Considering the point-by-point or line-by-line material consolidation mechanics, the fire-retardant options will further shrink if they have to be processed by additive methods. Research has led to specific options such as the Nylon FR series, ULTEM series, PAEK, and PEEK, processed by both selective laser sintering and fused deposition modelling. This paper reviews the current state of the additive processing of fire-retardant materials, clearly elucidating the material, process, structure, and property relationships and the fire-retardant standards. (C) 2019 Elsevier Ltd. All rights reserved.