On the Relationship between Mechanical Properties and Crystallisation of Chemically Post-Processed Additive Manufactured Polylactic Acid Pieces

A P Valerga; S R Fernandez-Vidal; F Girot; A J Gamez

doi:10.3390/polym12040941

On the Relationship between Mechanical Properties and Crystallisation of Chemically Post-Processed Additive Manufactured Polylactic Acid Pieces

Polymers (Basel). 2020 Apr 18;12(4):941. doi: 10.3390/polym12040941.

Authors

A P Valerga¹, S R Fernandez-Vidal¹, F Girot^{2

3}, A J Gamez⁴

Affiliations

¹ Department of Mechanical Engineering and Industrial Design, School of Engineering, University of Cadiz, Av. Universidad de Cádiz, 10, E-11519 Puerto Real, Cadiz, Spain.
² IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.
³ Faculty of Engineering, University of the Basque Country, Alameda de Urquijo s/n, 48013 Bilbao, Spain.
⁴ Mathematical Engineering Research Group, School of Engineering, University of Cadiz, Av. Universidad de Cádiz, 10, E-11519 Puerto Real, Cadiz, Spain.

Abstract

Nowadays, improvement of the surface finish of parts manufactured by fused deposition modelling is a well-studied topic. Chemical post-treatments have proven to be the best technique in terms of time consumption and smoothness improvement. However, these treatments modify the structure of the material and, consequently, its mechanical properties. This relationship was studied in this work. In this case, on the basis of a previous study on crystallisation, polylactic acid pieces were subjected to different post-treatments to evaluate their effects on the sample's mechanical properties, i.e., tensile strength and hardness. Models were obtained according to their percentage of crystallisation, which was related to the different treatments, as well as immersion time. Dramatic changes were obtained within a wide range of material behaviour with some treatments. Specifically, changes were obtained in the maximum stress (from 55 to 20 MPa), in elongation (from 3% to 260%), and in the hardness scale (Shore D to A).

Keywords: biodegradable polymer; crystallite; finishing processes; fused deposition modelling; hardness; manufacturing design; polylactic acid; tensile strength.