Viscous sintering kinetics of biopolymer filaments extruded for 3D printing
Résumé
The characteristic time for viscous sintering of thermoplastics is an important parameter in industrial processes such as welding, rotational moulding but also additive manufacturing. For Additive Manufacturing by Material Extrusion (AM-ME), it gives information about spreading dynamics. An experimental setup was designed to characterize the viscous sintering of cylindrical filaments (extruded for AM-ME) under controlled thermal conditions. It consists of a small thermally controlled oven, coupled with an image acquisition system to followup the coalescing cylinders' cross section shape. The evolution of the bonding angle and the convexity index can be calculated to evaluate the temperature dependence of the characteristic time for viscous sintering and the final sintering quality. This approach was applied to glycerol plasticized zein, a biopolymer formulated for AMME processing. A processing window (120-130 degrees C) was identified where a high convexity index is reached within a characteristic sintering time close to that of ABS in AM-ME processing conditions.
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