Powder bed fusion of poly(phenylene sulfide)at bed temperatures significantly below melting

In this paper, the authors present evidence of printing poly(phenylene sulfide)(PPS), a high-performance polymer, via powder bed fusion (PBF)using a bed temperature of 230 °C, which is significantly below both its observed melting temperature (T_m ˜ 285 °C)and its observed onset temperature of crystallization (T_c ˜ 255 °C). This contradicts existing material screening guidelines for PBF, which suggest maintaining bed temperature above the observed onset of crystallization. The authors believe that printing PPS at a comparatively-low bed temperature is beneficial for minimizing the occurrence of PPS side-reactions (e.g., chain extension, branching, and crosslinking)during printing and for enabling processing of a high-temperature polymer on “standard” PBF printers, which typically have maximum build temperatures below 250 °C. Existing methods for theoretically determining processing bounds were used to predict a range of energy densities at which PPS can be printed. One combination of process parameter values was selected based on machine constraints imposed by typical PBF machines not designed to print high-temperature polymers and used to fabricate multilayer, complex parts. The presented process parameters result in final part density upwards of 1.18 g/cm³ and ultimate tensile strength and elongation of 62 MPa and 3.3%, respectively. 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.