Powder Bed Fusion of Poly(phenylene sulfide) (PPS) at Temperatures Significantly Below Melting Temperature
Polymer powder bed fusion has an established history of being used to manufacture end-use parts for the medical and aerospace industries. One of the biggest obstacles to a broader adoption of this technology is the limited number of polymeric materials available for processing. While there has been progress in expanding the materials catalog, specifically with high performance, high temperature polymers, such as poly(ether ether ketone) (PEEK) and poly(ether ketone) (PEK), they often require expensive, high-temperature machines in order to minimize the difference between the processing temperature and the melting point of the polymer.
Poly(phenylene sulfide) (PPS) has a melting temperature around 285 °C, which results in a minimum temperature difference of 65 °C for many commercial printers. Although challenging according to prior literature guidelines, the authors believe “low temperature printing” of PPS is specifically important to minimize the undesirable side reactions that may occur at prolonged exposure to high temperatures. Enabling printing of a high temperature polymer, like PPS, using a more common machine is an added benefit. In this paper, the authors present evidence of printing PPS using a bed temperature of 200 °C, which is below its observed onset of crystallization temperature and in contrast to existing material screening guidelines for PBF. The presented process parameters result in final part density upwards of 89% theoretical density (1.19 g/cc) and ultimate tensile strength and elongation of 62 MPa and 3.3 %, respectively. These values are within 11 % of published values for injection molding PPS, excepting the 300% increase in elongation. The presented work outlines the polymer property informed process parameter selection and the resultant part properties. Hypotheses on the generalizability of low temperature PBF printing of high performance polymers, and steps towards updating materials and process parameter selection guidelines for PBF are also presented.
C. Chatham, T. Long, and C. Williams. “Low-temperature powder bed fusion processing of poly(phenylene sulfide)” Solid Freeform Fabrication Symposium. August 15, 2018. Austin, TX.