Abstract
Biodegradable poly(L-lactic acid) (PLLA) fibers were processed by a two-step melt-spinning method (melt extrusion and hot draw) from PLLA with three different viscosity-average molecular weights (494,600, 304,700, and 262,800). Before spinning, the polymer flakes were first milled into powders and dried under vacuum. Viscosity-average molecular weight of PLLA following the fabrication process was monitored. Tensile properties of as-spun and hot-drawn fibers were investigated. Morphology of the PLLA fibers was viewed under a scanning electron microscope. Crystallinity of these fibers was assessed by thermogram analysis of differential scanning calorimetry. Results showed that the extent of decrease in the viscosity-average molecular weight of PLLA dropped sharply by 13.1-19.5% during pulverization and by 39.0-69.0% during melt-extrusion. The hot-draw process in this study had a little effect on the viscosity-average molecular weight of PLLA. Smoother fibers could be obtained for the die temperature at least 230°C for raw materials with higher crystallinity (more than 75%) and at least 220°C for raw materials with lower crystallinity (about 60%). The as-spun fibers showed crystallinity of 16.5-22.8% and the value increased to 50.3-63.7% after hot draw. Tensile moduli of the as-spun fibers were in the range of 1.2-2.4 GPa, which were raised to 3.6-5.4 GPa after hot draw. The final PLLA fibers with 110-160 μm diameters showed tensile strengths of 300-600 MPa.
Original language | English |
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Pages (from-to) | 251-260 |
Number of pages | 10 |
Journal | Journal of Applied Polymer Science |
Volume | 81 |
Issue number | 1 |
DOIs | |
Publication status | Published - 5 Jul 2001 |
Keywords
- Biodegradable fibers
- Melt spinning
- Poly(L-lactic acid)
- Tensile properties
- Viscosity-average molecular weight
ASJC Scopus subject areas
- General Chemistry
- Surfaces, Coatings and Films
- Polymers and Plastics
- Materials Chemistry