Shear viscosity measurements on Polyamide‐12 polymers for laser sintering

Purpose – Laser sintering kinetics and part reliability are critically dependent on the melt viscosity of materials, including polyamide 12 (PA‐12). The purpose of this paper is to characterise the viscosity of PA‐12 powders using alternative scientific methods: constrained boundary flows (capillary rheometry) and rotational rheometry.Design/methodology/approach – Various PA‐12 powders were selected and characterised by both techniques. Measurement of molecular weight was also carried out to interpret the viscosity data.Findings – Results demonstrate conventional pseudoplastic flow in all PA‐12 materials. Zero‐shear viscosity has been quantified by rotational rheometry; a notable observation is the striking difference between virgin/used PA‐12. This is interpreted in terms of molecular weight and chain structure modifications, arising from polycondensation of PA‐12 held at the bed temperature during laser sintering.Research limitations/implications – Accurate zero‐shear viscosity data provide scope for us...

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