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Printability and mechanical performance of biomedical PDMS-PEEK composites developed for material extrusion

journal contribution
posted on 08.01.2021, 12:09 by James Smith, Simin Li, Elisa Mele, Athanasios Goulas, Daniel Engstrom, Vadim Silberschmidt
Polydimethylsiloxane (PDMS) materials are widely adopted in the manufacture of facial prostheses, lab-on-chip devices and scaffolds for soft-tissue engineering applications; however, their processing by additive manufacturing (AM) has proved challenging. Liquid silicone rubbers (LSRs) are favoured for their high shape fidelity when cast, but their low viscosity and surface tension often prevent self-support, post-extrusion. Poly(ether) ether ketone (PEEK) particle reinforcement through interfacial bonding has proven to enhance key properties of PDMS, expanding their end-use functionality. Still, the impact of such particles on the printability of LSR-PDMS is not explored. In this study, for the first time, solvent-free biocompatible PDMS-PEEK composites (up to 30 wt% PEEK) were successfully characterised for material extrusion (ME) printing. Rheological analysis confirmed shear-thinning of all PDMS-PEEK composites under applied load (within the tolerances of the printer) and dominant storage moduli at rest (i.e. prints can self-support), considered highly desirable for ME-based printing. Attained rheological datasets were used to guide initial printability studies, which revealed finer track fidelity with rising fractional content of PEEK, at comparable print speed and displacement values. Composites with higher PEEK content demonstrated significant increases in Shore A hardness and stiffness (in tension and compression) in bulk form. Last but not least, enhanced shape fidelity (thanks to PEEK reinforcement) and geometrical autonomy further expanded the manufacturing freedom of PDMS, whereby infill density could be controlled in order to increase the range of mechanical performance, previously unachievable with conventional casting fabrication. Fundamentally, this could lead to the manufacture of bespoke spatially graded multi-material structures and devices that could be used to replicate the heterogenous properties of soft human tissues and in other advanced material applications.

Funding

EPSRC Centre for Doctoral Training in Additive Manufacturing and 3D Printing

Engineering and Physical Sciences Research Council

Find out more...

National Institute of Health Research (NIHR) Children and Young People MedTech Co-operative (NIHR CYP MedTech)

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering
  • Mechanical, Electrical and Manufacturing Engineering

Department

  • Materials

Published in

Journal of the Mechanical Behavior of Biomedical Materials

Volume

115

Publisher

Elsevier

Version

AM (Accepted Manuscript)

Rights holder

© Crown Copyright

Publisher statement

This paper was accepted for publication in the journal Journal of the Mechanical Behavior of Biomedical Materials and the definitive published version is available at https://doi.org/10.1016/j.jmbbm.2020.104291.

Acceptance date

21/12/2020

Publication date

2021-01-05

Copyright date

2021

ISSN

1751-6161

Language

en

Depositor

Dr Thanos Goulas. Deposit date: 6 January 2021

Article number

104291