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The effect of crystallinity on the deformation mechanism and bulk mechanical properties of PLLA

Paper ID Volume ID Publish Year Pages File Format Full-Text
12540 799 2005 12 PDF Available
Title
The effect of crystallinity on the deformation mechanism and bulk mechanical properties of PLLA
Abstract

Poly (l-lactide) is a widely studied biomaterial, currently approved for use in a range of medical devices, however, most in vitro studies have so far focussed upon either the bulk properties during degradation and/or deformation, or on the microstructure of the unloaded material during degradation. This study aimed to combine these approaches through the technique of simultaneous small-angle X-ray scattering and tensile testing at various stages of degradation up to 8 months, on material with a range of induced microstructures. Results showed that the amorphous material deformed by crazing in the dry, wet and degraded states, however, the mechanism by which the craze developed changed significantly on hydration. Despite this difference, there was little change in the bulk mechanical properties. Crystalline materials deformed through crystal-mediated deformation, with contributions from both cavitation and fibrillated shear, but surprisingly, differences in the length scales within the spherulitic structure caused by annealing at different temperatures had very little effect on the mechanism of deformation, though differences were seen in the bulk properties. Furthermore, hydration had little effect on the crystalline materials, though degradation over 8 months resulted in loss of mechanical properties for samples produced at higher annealing temperatures. In conclusion, the introduction of crystallinity had a huge effect on both bulk and microscopic properties of PLLA, but the spherulitic structure of the crystalline material affected the bulk properties significantly more than it did the micromechanism of deformation.

Keywords
Polylactic acid; Degradation; XRD (X-ray diffraction); Mechanical properties; Crystallinity
First Page Preview
The effect of crystallinity on the deformation mechanism and bulk mechanical properties of PLLA
Publisher
Database: Elsevier - ScienceDirect
Journal: Biomaterials - Volume 26, Issue 29, October 2005, Pages 5771–5782
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering