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The effect of layer height and post-curing temperature on the shape memory properties of smart polymers in vat photopolymerization

Anna Danielak (Department of Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark)
Siddharth Singh Chauhan (Department of Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark)
Aminul Islam (Department of Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark)
Jacek Andrzejewski (Institute of Materials Technology, Poznan University of Technology, Poznan, Poland)
David Bue Pedersen (Department of Mechanical Engineering, Technical University of Denmark, Lyngby, Denmark)

Rapid Prototyping Journal

ISSN: 1355-2546

Article publication date: 23 September 2022

Issue publication date: 27 January 2023

230

Abstract

Purpose

The purpose of this paper is to evaluate the influence of layer thickness and post-curing temperature on shape memory properties in components manufactured by stereolithography.

Design/methodology/approach

Layer thicknesses of 20 and 100 µm and 22 and 45°C for post-curing temperature were selected following the design of experiments approach. Tensile and bending tests were applied for quantitative evaluation of the shape memory effect (SME). Qualitative analysis was performed using complex geometries and computed tomography as a measurement tool. Additionally, the degree of photopolymerization and glass transition temperature (Tg) were evaluated.

Findings

The tensile test resulted in fixity and recovery ratio values close to 100%. In bending, they varied between 97%–111% for fixity and 88%–95% for recovery. The layer thickness was found to have a higher influence on the SME. In complex structures, SME was dependent on geometry and less sensitive to variation in process parameters. The post-curing temperature had a higher influence on the photopolymerization and Tg. Average Tg of 77.5°C was achieved at 45°C, compared to 73.1°C at 22°C.

Originality/value

In the current state of the art in the processing of shape memory polymers with vat photopolymerization typically, the chemical composition or the thermal and deformation patterns are studied. The effect of the processing parameters is, however, not explored. This paper aims to close the research gap and facilitate the process optimization towards high fixing and recovery characteristics.

Keywords

Acknowledgements

The authors would like to thank 3DM company for supporting information regarding the material, Professor Kristoffer Almdal for sharing his expsertise on the FTIR technique and Carsten Gundlach and Sina Baier-Stegmaier for their advice on the CT scanning process.

Declaration of interest: The authors declare that they have no conflict of interest.

Citation

Danielak, A., Chauhan, S.S., Islam, A., Andrzejewski, J. and Pedersen, D.B. (2023), "The effect of layer height and post-curing temperature on the shape memory properties of smart polymers in vat photopolymerization", Rapid Prototyping Journal, Vol. 29 No. 2, pp. 354-365. https://doi.org/10.1108/RPJ-06-2021-0138

Publisher

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Emerald Publishing Limited

Copyright © 2022, Emerald Publishing Limited

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