Effect of thermal treatments on the laser sinterability of cryogenically milled polybutene-1

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.