Fused filament fabrication of copolyesters by understanding the balance of inter- and intra-layer welding

Abstract

To extend the diversity of commercial materials relevant for fused filament fabrication (FFF), the relation of nozzle temperature and layer thickness with respect to final product mechanical performance is examined for the less studied group of (co)polyesters, considering tensile and impact strength and microscopic imaging. It is demonstrated that with limited polymer degradation, one can focus on increasing the layer height (from 0.1 to 0.3 mm) by tuning of the contribution of inter-layer welding, whereas with significant degradation, a lower layer height (0.1 mm) is needed to exploit the contribution of intralayer welding for which a higher nozzle temperature (e.g. 260°C) is beneficial. The relevance of degradation is studied by both melt flow index and rheological analysis. The study ultimately provides the best FFF parameters for three commercial copolyesters and highlights the competition of inter-and intra-welding as a key microscopic material design strategy.

Setting the Optimal Laser Power for Sustainable Powder Bed Fusion Processing of Elastomeric Polyesters: A Combined Experimental and Theoretical Study

“…The test specimens built in the XY direction showed higher tensile strengths and tensile strains at break. Increasing led to a decrease in the tensile properties, consistent with the recent FFF work of Fernandez et al [ 45 ]. The flexural modulus showed a small dependency on both and the build orientation, while the impact strength showed a slight increase if was increased in the XY-plane.…”

Molecular Pathways for Polymer Degradation during Conventional Processing, Additive Manufacturing, and Mechanical Recycling

“…Fernandez et al [195] assessed the influence of the filament production, the printing temperature, and the printing velocity on the degradation of copolyesters. It was observed that printing at lower velocities and at higher temperatures led to an increased degradation of one of the material grades assessed.…”

Exploiting mono‐ and hybrid nanocomposite materials for fused filament fabrication with acrylonitrile butadiene styrene as polymer matrix

“…An important design aspect is the control of the coalescence degree between FFF deposited filaments as this degree is associated to the final part strength. [8][9][10][11][12] Coalescence can be realized via the surface contact between deposited filaments, followed by neck growth driven by surface tension variation, so-called sintering, and the molecular diffusion and entanglement of polymer chains through/along the interface. 13 It has been specifically reported that the neck growth has a significant effect on the coalescence, but it is quickly hindered in FFF due to the rapid cooling rates.…”