In-situ X-ray and thermal imaging of 3D printed PLA*

In-situ WAXS together with FLIR imaging was performed during 3D FDM printing of PLA filaments. The results highlighted the importance of the temperature profiles during printing on the structure/property relationships of the samples. Printing along short axis resulted in increased thermal retention, higher degrees of crystallinity and mechanical strength relative to samples printed along the long axis. Neutron reflectivity used to construct a model of the interdiffusion between filaments as a function of time and temperature. Lattice Boltzmann calculations were used determine the temperature of the filament as a function of nozzle temperature and extrusion speed. The thermal conduction between filaments in the vertical and horizontal direction was measured at four different nozzle temperatures and the interdiffusion was determined by scanning electron microscopy. The data showed large difference during printing between adjacent filaments. Fusion, was shown to occur when the diffusion length exceeded R_g of PLA, occurred first in horizontal direction when the nozzle temperature exceeded 215°C and in the vertical direction when it exceeded 245°C.