A novel extrusion process for the production of polymer micropellets

Traditional micropellet and powder-based polymer processing techniques, such as powder bed fusion, compression molding, and rotational molding have shown an increased demand in polymer processing. These processes require powders and micropellets with a small particle size, narrow size distribution and defined geometry for a variety of polymer resins. Therefore, micropelletization technologies, where particles in the size range of 50-1,000 mu m are generated, have been attracting growing attention over the past decade. A new technique, presented here, yields micropellets with a controlled morphology and narrow particle size distribution. In this process, a polymer melt is extruded through a capillary and is subsequently stretched with a hot airstream until flow instabilities or melt fracture cause it to break up into particles. Small changes in process conditions result in different size distributions and particle shapes, such as lenticular pellets, fibers, and strand segments. This work shows how processing parameters and different polymer materials influence the produced micropellets. Depending on the processed polymer resin and process conditions, spherical particles with sizes ranging from 50 to 1,000 mu m can be produced using the novel extrusion technique. Comprehensive design of experiment and data analysis was used to establish a more detailed understanding of the micropelletization process. POLYM. ENG. SCI., 58:2264-2275, 2018. (c) 2018 Society of Plastics Engineers