Influence of rheology on 3D printing with heterogeneous reactive polyurethane reagents

Wu, Y., Zhou, Z., Lu, X., Stimpson, A., Casarino, A., Hayes, W. ORCID: https://orcid.org/0000-0003-0047-2991, Tuck, C., Wildman, R. and Irvine, D. (2026) Influence of rheology on 3D printing with heterogeneous reactive polyurethane reagents. Materials Advances. ISSN 2633-5409 doi: 10.1039/D5MA01460C (In Press)

Abstract/Summary

The successful printing of multi-layer, multi-material polyurethane woodpile structures with good structural fidelity and rigidity was demonstrated by via polymerisation-based reactive extrusion processing. Two heterogenous, viscoelastic feed-streams, i.e. a diol and a polymeric isocyanate reagent (which was selected to improve flow-process safety), which contained fumed silica microparticles reagents were mixed and printing performance was shown to be governed by relative rheological properties of the feeds and by the polymerisation exotherms generated upon mixing. The influence of the polymer rheological characteristics on the polymerisation, exotherms and extent of reaction achieved has not been extensively explored to date. To understand the impact of feedstock characteristics on the printing process, polydimethylsiloxane coated fumed silica particles were added the two polymer feeds. These were designed to act as: (a) inorganic functional materials to modify the materials properties of the printed devices, (b) an additive that modify the feed materials rheology and (c) inorganic fillers that moderate the polymerization exotherm. The experimental results demonstrated that the viscosity and elasticity of the poly(isocyanate) feed, which is tuned through silica particle content, must be comparable to or lower than those of the diol feed. This requirement was attributed to the mixing characteristics that develop when the two feed streams were combined, which ultimately determined the interfacial reactive area created and dictated the rate/extent of the step-growth reaction.

Item Type	Article
URI	https://centaur.reading.ac.uk/id/eprint/129699
Identification Number/DOI	10.1039/D5MA01460C
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Publisher	Royal Society of Chemistry
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