2012 Volume 53 Issue 10 Pages 826-834
The shrinkage of poly(lactic acid)(PLA) fiber fabrics with the monofilament(PLA-mono) yarn of low fineness or multifilament(PIA-multi) yarn of high fineness has been examined using mixtures of good and poor solvents. The good solvent---chloroform, dichloromethane or 1, 2-dichloroethane---was used with a poor solvent, ethanol. The degree of shrinkage for both fabrics increased with increasing the good solvent molar fraction. Higher molar fraction of the good solvent was necessary for the PLA-multi than the PLA-mono to establish the same degree of shrinkage. By using dichloromethane as a good solvent, the time required establishing the shrinkage was shorter, and the reduction of the strength of the shrunken fabrics was smaller than those of other good solvents. From the dependence of the estimated solvation equilibrium constants of the three good solvents on the temperature, the solvation enthalpy for the PLA-multi was estimated about 25% larger than that for the PLA-mono, consistent with the higher molecular orientation in the filament of PLA-multi compared with the PLA-mono, obtained from the polarized FT-IR absorption spectra. Such textile, consisting of the shrunken and the unshrunken portions, was produced that exhibited the unevenness, the irregularity of the transparency, and the color contrast after dying.
