Spunlike yarns having free ends are made from continuous filament yarn by fluid-jet texturing. The fibrous elements that make up the yarn have irregular and varying cross-sectional shapes, said fibrous elements being forked and merged in a fortuitous manner. The spunlike yarns may also contain fibrous elements that extend substantially continuously throughout the length of the yarn.
A polyester filament yarn made by treating a polyester filament with an aqueous alkali solution, which filament is composed of a core extending over the length of filament and a plurality of fins bonded to the core over the length of the core and radially extending from the core, and which satisfies the following three requirements: wherein SA and DA are cross-sectional area and diameter of the core, and SB, LB and WB are cross-sectional area, maximum length and maximum width of the fins, respectively. The fins are at least partially separated from the core by the alkali treatment. A fabric composed of the filament yarn has soft touch and feeling, high bulkiness and uniform appearance.
High strength, high modulus, continuous filament aromatic polyamide yarns are stretch broken under high tension while being sharply deflected in a lateral direction by mechanical means to provide a sliver which is processed by conventional means to a high strength, high modulus spun yarn. The broken ends of the fibers are highly fibrillated to fibrils having lengths of 50-350 times the diameter of the unfibrillated portion of each fiber.
A method for preparing cross-sections of yarn samples along the plane perpendicular to the yarn's longitudinal axis is disclosed. This method involves the steps of passing the yarn through a hollow capsule so that the axes of the yarn and the capsule are aligned in parallel, tensioning the yarn to remove any crimp, forming a solid stub inside the capsule to fix the position of the tensioned yarn, and then cross-sectioning the stub perpendicular to its longitudinal axis.
Ferromagnetic recording elements with improved physical properties have from 20 to 50% of the volume of ferromagnetic particles replaced by nonmagnetic particles of a size smaller than the thickness of the magnetic layer.
A PTFE fiber that is adapted to be sewn at high speeds. The fiber has a toughness greater than about 0.36 grams per denier (g/d). A range for the toughness is from about 0.36 to about 1.01 g/d, with a preferred range being from about 0.50 to about 0.80 g/d. The toughness of the inventive PTFE fiber is most preferably about 0.60 g/d. The inventive fiber has a peak engineering stress greater than about 1.6 g/d and a break strain greater than about 15.5 percent. A preferred range for the peak engineering stress is from about 3.0 g/d to about 5.0 g/d, and a preferred range for the break strain is from about 20 percent to about 50 percent. Most preferably, the peak engineering stress is about 4.4 g/d, and the break strain is about 24 percent. In another aspect, this invention provides a process for making a fiber that involves providing a PTFE fiber and heating the PTFE fiber to a temperature of from about 300.degree. C. to about 500.degree. C., while overfeeding the PTFE fiber at an overfeed of up to about 70 percent. A preferred range for the temperature is from about 350.degree. C. to about 450.degree. C., and a preferred range for the overfeed in the overfeeding step is from about 10 percent to about 20 percent. Most preferably, the temperature in the heating step is about 400.degree. C. and the overfeed in the overfeeding step is about 15 percent. The PTFE fiber may be used as a filament for an improved dental floss, and is also suited for an improved bearing material.
