Effect of thermal treatments on the laser sinterability of cryogenically milled polybutene-1. (5th September 2018) - Van den Eynde, Michael
Abstract: This paper demonstrates how thermal treatments can be used to enable the laser sintering (LS) of polybutene-1 (PB-1). One of the major issues with the examined PB-1 grade is the limited thermal operating window. At temperatures slightly below 90 °C crystallisation is too fast, resulting in warpage during processing. Above 90 °C, however, the powder becomes increasingly sticky, limiting the maximum bed temperature that can be applied in a laser sintering station. In this work, the problem is remediated by annealing the powder at 115 °C, which creates a more perfect crystal structure with a sharper melting onset. An alternative treatment of melting, slowly cooling and aging the sample at room temperature creates a powder with a stabilised crystal structure, which has a sharp melting onset at 120 °C and thus also a broader thermal window. Test parts were created on an LS machine validating the increase in processability. Graphical abstract: Unlabelled Image Highlights: The window between the crystallisation and melting peaks of the examined Polybutene-1 is too small for laser sintering. Proposed annealing and melting treatments both succeed in significantly broadening the thermal window. Studies on powder flow, coalescence and crystallisation show the viability of the Polybutene-1 powder for laser sintering. Test parts were successfully produced in laser sintering using the treated powders.