On the use of cellulose acetate as a structural material for parts produced by fused filament fabrication

Cellulose acetate (CA) is a semi-synthetic and biodegradable polymer that represents a fair alternative as a structural material for fused filament fabrication (FFF). With very few studies on the subject, the present work aims to broaden and deepen the understanding of FFF of CA with a degree of substitution of 1.7. A fine characterisation of the microstructure and mechanical properties of printed parts and the investigation of the effect of water on this hydrophilic polymer were pursued. Highly dense plasticised CA specimens with a porosity lower than 2% were successfully manufactured. Geometrical discrepancies between the designed and fabricated parts, together with the surface rugosity, inherent from this 3D printing technique, were carefully studied by X-ray microtomography. Ultimately, the printed samples showed no alteration of the intrinsic material's composition, yield strength and tensile modulus, comforting the potential of FFF of CA-based parts for structural applications. In addition to the geometrical imperfections, the plasticising effect of water on CA was quantified as the elastic and yield properties were significantly decreased after water saturation, evidencing the need to account for the two effects when designing, storing and using FFF CA parts.