Ammonium Polyphosphate and Pentaerythritol as a Flame Retardant System for Polyamide 12 in Selective Laser Sintering

This study investigates the incorporation of an intumescent flame retardant system, based on a combination of ammonium polyphosphate (APP) and pentaerythritol (PER), into polyamide 12 (PA12) for selective laser sintering (SLS). The influence of processing parameters and filler content on the mechanical and fire properties of the manufactured components is analysed. Particle size analysis and powder density measurements were conducted to assess the powder characteristics, revealing impact on the powder density of the mixtures. DRIFT measurements show that the flame retardant additives require only minor adjustments to the energy input during SLS processing. Manufacturing was conducted with different energy densities, to assess the ideal manufacturing parameters. DSC and ATR measurements indicate that the addition of the flame retardant system alters the crystallization behaviour of PA12, promoting the formation of the α-modification and influencing the crystal morphology. Tensile tests demonstrate that while Young's modulus remains comparable to that of non-flame retardant PA12, the tensile strength and elongation at break are reduced. LOI testing confirms the effectiveness of the flame retardant system, with increasing additive fractions leading to improved flame retardancy. Cone calorimeter measurements reveal a significant reduction in both total heat released (THR) and peak heat release rate (pHRR) with the incorporation of the APP-PER system, highlighting its effectiveness in mitigating heat release and suppressing flame propagation during combustion.

Presentation language: EN