Effects of reuse on morphology, size and shape distributions of PA 12 powder in selective laser sintering and quality of printed parts

• Published in: Journal of polymer research 2023-02, Vol.30 (2), Article 48
• Main Authors: Alo, Oluwaseun A., Otunniyi, Iyiola O., Mauchline, David
• Format: Article
• Language: English
• Subjects: Agglomeration; Aspect ratio; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Circularity; Correlation coefficients; Dimensional analysis; Image analysis; Industrial Chemistry/Chemical Engineering; Laser sintering; Morphology; Original Paper; Polymer Sciences; Powders; Rapid prototyping; Recycling (Waste, etc.); Roundness; Shape; Sintering; Sintering (powder metallurgy); Statistical analysis; Thickness
• ISSN: 1022-9760; 1572-8935
• DOI: 10.1007/s10965-022-03423-6

Study of effects of reuse on the extrinsic properties of polymer powder is important for creating an effective powder recycling protocol in selective laser sintering (SLS). Therefore, this work investigated the effects of repeated use of PA 2200 powder during SLS on the powder particles’ morphology, size, and shape distributions and how this impacts the quality of printed parts. Scanning electron microscopy (SEM) imaging revealed presence of potato-shaped, elongated, and relatively few near-spherical particles in virgin and reused powders. Slight variation in the size distributions was observed with increase in the cumulative build time due to agglomeration and breaking of powder particles. The observed lower span and average size of reused powders compared to the virgin powder could be attributed to the effect of particle fragmenting being more predominant compared to effect of particle coalescence and agglomeration. From image analysis, distributions of circularity, aspect ratio, roundness, and solidity of the powder particles vary with increase in cumulative build time. The strong correlation between the cumulative build time and the various shape descriptors was also confirmed by statistical analysis. Dimensional variation was observed in the printed parts as the number of powder reuse cycles increased. Values of the correlation coefficients indicate high correlation between the thickness of sintered parts and each of span, average AR, average roundness, and average solidity while almost no correlation exists between the thickness and average circularity.