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Alkali etching of a poly(lactide) fiber
Shih-Po Sun1, Mei Wei, James R Olson
1Polymer Program, Institute of Materials Science, and Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, Connecticut 06269-3136, USA.
ACS Applied Materials & Interfaces
|April 2, 2010
Summary
Alkali etching of poly(l-lactic acid) fibers is a surface reaction. Its rate depends on time, temperature, and alkali concentration, allowing prediction of fiber weight loss.
Area of Science:
- Materials Science
- Polymer Chemistry
Background:
- Poly(l-lactic acid) (PLLA) is a biodegradable polymer with diverse applications.
- Surface modification of PLLA fibers is crucial for tailoring their properties.
- Alkali etching is a common method for polymer surface treatment.
Purpose of the Study:
- To investigate the kinetics and mechanisms of alkali etching on PLLA fibers.
- To determine the influence of etching parameters on the surface hydrolysis reaction.
- To develop a predictive model for PLLA fiber weight loss during etching.
Main Methods:
- PLLA fibers were exposed to sodium hydroxide solutions.
- Etching parameters studied: time (0-1.5 h), concentration (0.25-3 mol/L), and temperature (25-80 °C).
- Weight loss was measured gravimetrically; mechanical properties and crystallinity were analyzed.
Main Results:
- Alkali etching was confirmed as a surface hydrolysis reaction, not a bulk reaction.
- Weight loss rate decreased with decreasing fiber radius.
- Increased fiber crystallinity was observed due to surface-limited etching.
- Etching rate showed nonlinear dependence on alkali concentration and followed Arrhenius behavior with temperature.
Conclusions:
- The weight loss of PLLA fibers during alkali etching is primarily a surface phenomenon.
- Etching kinetics are governed by a combination of chemical hydrolysis and mass transport.
- An overall expression can predict PLLA fiber weight after etching based on key parameters.
