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Multi-walled carbon nanotubes (CNTs) as nano-reinforcements were introduced to facilitate the laser sintering process and enhance the thermal and mechanical properties of polymeric composites. A dual experimental-theoretical method was proposed to evaluate the processability and predict the process parameters of newly developed CNT-coated polyamide 12 (CNTs/PA12) powders. The thermal conductivity, melt viscosity, phase transition and temperature-dependent density and heat capacity of PA12 and CNTs/PA12 powders were characterized for material evaluation. The composite powders exhibited improved heat conduction and heat absorption compared with virgin polymer powders, and the stable sintering range of composite powders was extended and found to be favourable for the sintering process. The microstructures of sintered composites revealed that the CNTs remained at the powder boundaries and formed network architectures, which instantaneously induced the significant enhancements in tensile strength, elongation at break and toughness without sacrificing tensile modulus.

Well‐dispersed nanocomposite powder with spherical morphology and suitable particle size for processing by laser sintering was successfully produced by coating polyamide 12 (PA12) powder particles with carbon nanotubes (CNTs). Flexural, impact, and tensile test specimens produced by laser sintering the PA12–CNT powder showed no distortion and good definition. The density of the PA12–CNT laser‐sintered parts was higher than that of neat PA12, which the authors propose is mainly due to higher laser absorption by the CNT particles. Compared to the laser‐sintered PA12 parts, PA12–CNT parts showed enhanced flexural, impact, and tensile properties without sacrificing elongation at break. This enhancement may be attributed to the good dispersion of the CNT in the PA12 matrix and denser laser‐sintered parts. Considering the low weight percentage of CNT used (0.1 wt%), it would seem that the method used in this work is a cost efficient and effective way to produce polymer nanocomposite powders for laser sintering, while maintaining the optimum powder morphology for the laser sintering process and enhancing the mechanical properties of the laser‐sintered part. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers