Viscous sintering kinetics of biopolymer filaments extruded for 3D printing. (August 2019)

• Record Type: Journal Article
• Authors: Chaunier, Laurent; Valle, Guy Della; Lourdin, Denis; Réguerre, Anne-Laure; Cochet, Kévin; Leroy, Eric
• Is Part Of: Polymer testing. Volume 77(2019)
• Publication Date: 2019-08
• Subjects: Image analysis -- Material extrusion -- Model -- Viscous sintering -- Zein; Polymers -- Testing -- Periodicals; Polymères -- Tests -- Périodiques; 620.1920287
• DOI: 10.1016/j.polymertesting.2019.04.020
• Languages: English
• ISSNs: 0142-9418

Abstract

Abstract: 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 follow-up 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 AM-ME processing. A processing window (120–130 °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. Graphical abstract: Image 1 Highlights: Viscous sintering between filaments is assessed to access the temperature dependence of the phenomenon's characteristic time. Morphological analysis of coalescing cylinders' cross section is performed. Cross section convexity index is a sensitive indicator of the temperature dependence of the sintering quality. Characteristic time for viscous sintering, tvs, of plasticized zein was determined in the temperature range 80–140 °C. For plasticized zein, tvs at 120–130 °C matches that of ABS in 3D printing conditions.