In the paper, the results obtained for the fire-retardancy of ULTEM 9085 polymer composites manufactured by the fused deposition modelling (FDM) are summarized. The effects of processing parameters of FDM such as the percentage of infill, thickness of the sample, and the number of the solid layers on either side were experimentally evaluated against fire-retardancy parameters (burn length and heat release rate). Based on the results, all test samples of ULTEM 9085 were observed to have passed the test requirements specified in Federal Aviation Regulation (FAR) & EASA Certification Specifications (CS) Part 25 of Airworthiness standards for the aviation sector. The maximal burn length (approx. 80 mm) was registered for 30 % infill samples with zero solid layers on either side. Based on the results obtained it was concluded that the burn length was almost the same in all build directions. Moreover, inconsistent results were obtained for the heat release rate as a function of the thickness of the sample for different build directions. Though, certain clear effects were obtained regarding burn length as a function of infill percentage proving that fire-retardancy is the most effective at higher infill percentages.

Abstract

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Additive manufacturing has progressed rapidly, and the unique attributes of the layer-wise material consolidation are attracting ever increasing application potentials in critical sectors such as medical and aerospace industries. A lack of materials options has been the main bottleneck for the much wider uptake of these promising new technologies. Inventing new material alternatives has been central to most of the research attention in additive manufacturing in recent times. The current research is focused on evaluating the polyphenylsulfone polymer powders for the first time as fire-resistant candidate materials for processing by selective laser sintering, the most promising additive processing method for polymeric material systems. Experimental evaluations were undertaken based on a selective laser sintering test bed. Single layer and multi-layer samples were produced for microstructural and mechanical characterisations. The microstructural evaluations and the mechanical property results indicate sufficient intra- and inter-layer consolidation together with reasonable tensile property responses. The lower viscosity and thermal conductivity characteristics rendered lower tensile strengths, which will require some further attention in the future, for better consolidation and mechanical properties.