Abstract
The bulkiness of ten kinds of textured synthetic yarns has been determined by the following nine different methods to investigate the suitable testing method : (1) Testing method for the bulkiness of the fabrics into which the yarn is knitted. (2, 3) Testing methods for the bulkiness of the yarn layer prepared as below ; single yarns taken out from a hank treated or untreated in hot water are arranged side by side in the shape of yarn sheet. Three pieces of yarn sheets are piled up into a yarn layer so that yarn sheets intersect at right angles each other. (4, 5) Testing methods for the bulkiness determined by using the specimen weight caluculated from nominal denier of the yarn or using the weight considering yarn crimp extension index. (6, 7) Testing methods for the bulkiness of a yarn bundle cut off by a metallic rectangular cutter with knife edges, using a hank treated or untreated in hot water. (8, 9) Modified testing methods described in (6, 7); thickness of hank is, at first, measured prior to cutting off the hank toavoid deformation in thickness of yarn bundle due to cutting pressure.
The experimental results have been compared each other by the factor analysis to investigatethe relative locations of testing methods and problems to which each testing method is concerned. The results of comparative investigation showed that : (1) Testing methods for yarn bulkiness expressed as specific volume in cm3/g were divided into the two major categories, that is, the testing methods for cross-sectional compressibility and those for cross-sectional compactness ofyarn bundles. (2) Testing methods with a treatment of hanks in hot water were related to yarn compactness. On the other hand, testing methods without treatment of hanks in hot water were. related to yarn compressibility. (3) No correlation was found between yarn bulkiness and bulkiness of fabrics into which the yarn was knitted.
