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Probing the complex thermo-mechanical properties of a 3D-printed polylactide-hydroxyapatite composite using in situ synchrotron X-ray scattering

DOI: 10.1016/j.jare.2018.11.002 DOI Help

Authors: Tan Sui (University of Oxford; University of Surrey) , Enrico Salvati (University of Oxford) , Hongjia Zhang (University of Oxford) , Kirill Nyaza (Skoltech - Skolkovo University of Science and Technology; National University of Science and Technology “MISIS”) , Fedor S. Senatov (Skoltech - Skolkovo University of Science and Technology) , Alexei I. Salimon (Skoltech - Skolkovo University of Science and Technology; National University of Science and Technology “MISIS”) , Alexander M. Korsunsky (University of Oxford; Skoltech - Skolkovo University of Science and Technology)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Advanced Research

State: Published (Approved)
Published: November 2018
Diamond Proposal Number(s): 17541 , 21312

Open Access Open Access

Abstract: Polylactide (PLA)-hydroxyapatite (HAp) composite components have attracted extensive attentions for a variety of biomedical applications. This study seeks to explore how the biocompatible PLA matrix and the bioactive HAp fillers respond to thermo-mechanical environment of a PLA-HAp composite manufactured by 3D printing using Fused Filament Fabrication (FFF). The insight is obtained by in situ synchrotron small- and wide- angle X-ray scattering (SAXS/WAXS) techniques. The thermo-mechanical cyclic loading tests (0-20MPa, 22-56°C) revealed strain softening (Mullins effect) of PLA-HAp composite at both room and elevated temperatures (<56°C), which can be attributed primarily to the non-linear deformation of PLA nanometre-scale lamellar structure. In contrast, the strain softening of the PLA amorphous matrix appeared only at elevated temperatures (>50°C) due to the increased chain mobility. Above this temperature the deformation behaviour of the soft PLA lamella changes drastically. The thermal test (0-110°C) identified multiple crystallisation mechanisms of the PLA amorphous matrix, including reversible stress-induced large crystal formation at room temperature, reversible coupled stress-temperature-induced PLA crystal formation appearing at around 60°C, as well as irreversible heating-induced crystallisation above 92°C. The shape memory test (0-3.75MPa, 0-70°C) of the PLA-HAp composite demonstrates a fixing ratio (strain upon unloading/strain before unloading) of 65% and rather a ∼100% recovery ratio, showing an improved shape memory property. These findings provide a new framework for systematic characterisation of the thermo-mechanical response of composites, and open up ways towards improved material design and enhanced functionality for biomedical applications.

Journal Keywords: 3D-printed polylactide-hydroxyapatite composite; Mullins effect; thermo-mechanical behaviour; shape memory effect; small- and wide- angle X-ray scattering

Diamond Keywords: Additive Manufacturing

Subject Areas: Materials

Instruments: B16-Test Beamline

Added On: 22/11/2018 10:56


Discipline Tags:

Biomaterials Materials Science Composite Materials

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