title: Alkali etching of a poly(lactide) fiber.
abstract: Alkali etching of a poly(l-lactic acid) fiber was studied by exposing the fiber surface to sodium hydroxide solutions. The factors examined included the etching time (0-1.5 h), alkali concentration (0.25-3 mol/L), and etching temperature (25-80 degrees C). The extent of etching was determined gravimetrically. Both weight loss and mechanical testing results suggest that alkali etching is strictly a surface hydrolysis reaction, as opposed to a bulk reaction, and thus the weight loss rate decreases with a shrinking fiber radius. A slight increase in the fiber crystallinity observed from thermal analysis was interpreted as a result of surface-limited etching on a sheath-core fiber microstructure. The dependence of the rate on the alkali concentration is nonlinear, suggesting that the fiber weight loss rate is subject to both chemical hydrolysis and transport limitations. The dependence of the rate on the temperature follows the Arrhenius equation. The fiber weight after etching can thus be predicted by an overall expression combining all factors: time, temperature, concentration, and fiber diameter.
authors.affiliation: Polymer Program, Institute of Materials Science, and Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, Storrs, Connecticut 06269-3136, USA.
authors.forename: Shih-Po
authors.initials: SP
authors.lastname: Sun
authors.forename: Mei
authors.initials: M
authors.lastname: Wei
authors.forename: James R
authors.initials: JR
authors.lastname: Olson
authors.forename: Montgomery T
authors.initials: MT
authors.lastname: Shaw
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D003460:Crystallization; D006868:Hydrolysis; D007700:Kinetics; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning / Q000379:methods; D015233:Models, Statistical; D011091:Polyesters / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D011091:Polyesters; C033616:poly(lactide); D012972:Sodium Hydroxide