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Project

Increasing the sustainability of polymer powder-based Additive Manufacturing

Powder-based Additive Manufacturing (AM) includes Laser Sintering (LS) and Multi-jet Fusion (MJF). In the past, LS was mainly a rapid prototyping technique. By now it has evolved into a true manufacturing technique for complex, specialty products. Several polymers are suited as starting material for LS but polyamide 12 (PA12) is most often used. The build tray of an LS machine is filled with PA12 powder, kept at a temperature a few degrees below the PA12 melting temperature. A laser locally melts the powder by which the polymer grains coalesce. When the layer is completed, the build tray is lowered, a new layer of powder is spread on top of the previous one and the sintering process continues until the product is completely printed. A large fraction of un-sintered powder remains in the build tray. It appears to be very difficult to use this remaining, un-sintered polymer powder in the next printing effort due to the thermal stress it received during the preceding run. For successful printing, this recycled powder needs to replenished with 50% virgin powder. As a result, large amounts of recycled powder are currently discarded. To increase the sustainability of this manufacturing technique the re-use rate of PA12 should be increased to no longer have to discard any recycled powder. This project wants to come to a fundamental understanding of the relationship between the currently imposed thermal protocol during LS and MJF and the resulting physical and chemical changes to the PA12 powder during sintering as well while being left aside in the build tray. With this knowledge, new laser sinter protocols will be proposed to successfully sinter powders with a high concentration of recycled PA12 powder. In a next step, it will be explored to what extent the new sinter strategies can also be put at work to print powders from other polymers.

Date:28 Sep 2020 →  Today
Keywords:Polymers, Additive Manufacturing, Laser Sintering, Sustainability, PA12
Disciplines:Physical chemistry of materials, Polymer recycling, Polymer processing, Soft condensed matter, Solid state and soft matter chemistry
Project type:PhD project