Comparison between the properties of polyamide 12 and glass bead filled polyamide 12 using the multi jet fusion printing process

This study investigates the material and mechanical properties of both polyamide 12 (PA12) and reinforced glass bead PA12 composites, fabricated using a production scale additive manufacturing (AM) process. The printing studies were carried out using the production scale, Multi Jet Fusion powder bed fusion process. The study demonstrated that the chemical functionality and the thermal properties of the printed PA 12 parts and the glass bead composite, were similar. Almost identical infrared spectra were obtained demonstrating the same chemical functionality. Based on DSC measurements, the melting temperature was 184 degrees C and 186 degrees C and the associated cooling cycle temperature was 150 degrees C and 146 degrees C for the composite and the PA12 respectively. The percentage crystallinity of the glass bead composite was 24 %, compared with the 31 % obtained for the PA12 only parts. Based on mechanical tests, the addition of glass beads increased the tensile and flexural modulus by 85 % and 36 % and lowered the tensile and flexural strength by 39 % and 15 % respectively. The effect of print orientation during the MJF process was evaluated based on porosity and mechanical performance. Using X-ray micro computed tomography, it was demonstrated that the porosity of the PA12 and composite parts were less than 1 %. Polymer and composite parts printed in the ZYX orientation were found to exhibit both the lowest porosity and highest mechanical strengths.