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.

We examined the influence of the sewing direction on the amount of needle penetration in blind stitch machine sewing. The results obtained were as follows:The amount of needle penetration increased in the bias sewing seam comparing with the warp and weft ones, although the increasing percentages were different by fabric characteristics.From the inspection of seam stitch using a microscope, we observed some needle penetration patterns in accordance with fabric characteristics. As for the sewing directions, the patterns obtained from bias sewing seams were the most diversified.It was shown that the fabric was greatly affected by both the motions of feed dog and ridge forming disc when the needle was penetrating. In the case of bias sewing, the motion of feed dog caused the shear deformation of the fabric and in turn the tight and packed structure of woven fabrics, while no shear deformation was occurred in the case of both the warp and weft sewing. We examined that the increase of the amount of needle penetration and the diversification of patterns of needle penetration in bias direction sewmg, were caused by the change in fabric shear deformation under the feeding force mentioned above.It was shown that the shear rigidity G and tensile property EMT along sewing direction relating with the fabric deformation were quite important factors in considering the influence of sewing direction on the amount of needle penetration.