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Degradation studies on highly oriented poly(glycolic acid) fibres with different lamellar structures
Horacio Montes de Oca1, David F Farrar, Ian M Ward
1IRC in Polymer Science and Technology, School of Physics and Astronomy, University of Leeds, Leeds, UK. horacio.montesdeoca@smith-nephew.com
Acta Biomaterialia
|December 29, 2010
Summary
Degradation of poly(glycolic acid) (PGA) fibers shows that semi-rigid chains connecting crystalline domains are key to maintaining tensile strength. Rapid degradation of these tie molecules leads to a swift loss of fiber strength.
Area of Science:
- Materials Science
- Polymer Science
- Biomaterials Engineering
Background:
- Poly(glycolic acid) (PGA) is a biodegradable polymer used in various biomedical applications.
- Understanding the degradation mechanisms of highly oriented PGA fibers is crucial for predicting their performance and longevity.
- The relationship between fiber morphology, structural changes during degradation, and mechanical properties requires detailed investigation.
Purpose of the Study:
- To investigate the structural changes and degradation behavior of highly oriented poly(glycolic acid) (PGA) fibers in aqueous media.
- To elucidate the role of different phases within the PGA fibers during degradation.
- To establish structure-property relationships governing the tensile strength retention of PGA fibers.
Main Methods:
- Preparation of highly oriented poly(glycolic acid) (PGA) fibers with varying lamellar morphologies.
- Degradation studies in aqueous media at 37°C.
- Analysis using small- and wide-angle X-ray scattering (SAXS/WAXS) for structural characterization.
- (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy to identify different phases and their relaxation times.
Main Results:
- Two structural models of oriented PGA fibers with distinct lamellar morphologies were developed.
- PGA crystals were observed to grow preferentially along specific crystallographic directions during degradation.
- Three distinct phases (mobile amorphous, semi-rigid, and rigid crystalline) were identified within the fibers based on relaxation times.
- The mobile amorphous phase degrades rapidly with minimal impact on tensile properties.
- Semi-rigid chains connecting crystalline domains were identified as critical for stress transfer and deformation.
Conclusions:
- The semi-rigid chains acting as tie molecules between crystalline domains are primarily responsible for the tensile mechanical behavior of PGA fibers during degradation.
- Rapid degradation of these tie molecules leads to a significant and swift loss of fiber strength.
- The crystalline phase and its growth during degradation influence the overall mechanical integrity of the oriented PGA fibers.
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