In recent years, we have been reporting our research on composite yarns of mostly cotton content produced on a modified ring spinning system. Recently, we reported an improved method of producing an all staple-core spun yarn, and we have applied the same method to filament-core spinning, obtaining a yarn of greatly improved quality. The new filament-core yarn has almost total core coverage, does not strip, and is about 10% stronger (probably due to its improved yarn structure) than a conventional filament-core yarn. This paper briefly describes the new and conventional core spinning methods and evaluates nylon filament-core/cotton-wrap yarns produced with them. There is also a comparison of the cover factor, strip resistance, and microscopic cross sections of a few other core yarns (with Kevlar, fiberglass, and polyester cores). A significant improvement in the cover factor of the new yarn suggests that it may be very useful for sewing threads; ropes; twines; cables; special military, industrial, and surgical fabrics; and other textiles in which the high strength, durability, and a 100% cotton surface (for ease of finishing or coating) are important.

A new, better method of producing cotton covered/polyester staple-core yarn on a modified ring spinning frame is described. The method uses the concept of twisting a “sandwich” formed by two drafted strands of cotton (rovings) on the outside and a drafted strand of polyester on the inside, thus using a total of three rovings. The earlier method used only one cotton roving and one polyester roving [10]. The new method is simple and easily adaptable to the existing spinning frames; piecing of broken ends is also easy. A 67/33 cotton/high tenacity polyester staple-core yarn produced by the new spinning system is evaluated. The core of the yarn is almost totally covered with a firm sheath of cotton, giving the an appearance of a 100% cotton spun yarn. Compared with conventional yarns of 100% cotton and 67/33 cotton/polyester intimate blends, the core yarn is significantly stronger than the equivalent 100% cotton yarn and the intimate blend yarn of regular tenacity polyester. These yarns may be useful where a co-axial segregation of different fibrous materials is important or critical. The new staple-core spinning technology can be applied to produce yarns from a variety of core and sheath materials, such as Kevlar, PBI, Nomex, cotton, and wool, among others.

An oxalic acid-based system for chemically retting flax is tested and compared with enzymatic retting. The retting effect is substantially higher at pH 10 and 11 than at lower pH levels, and the optimal oxalic acid concentration is 50 mmol. The presence of the strong detergent sodium dodecyl sulfate (SDS) further enhances retting. The rate of retting with the oxalic acid/SDS mixture at pH 10 is strongly temperature dependent, and at 75°C the process is completed within 2 hours. Tests of fiber properties ( e.g., tex, tenacity, and elongation) indicate that the chemical/physical retting method pro duces fibers of textile quality that can be spun into flax-rich blends with cotton.

This paper discusses highloft perpendicular-laid nonwovens made with cotton, poly ester, and bicomponent bonding fibers rather than the usual synthetic fibers. Compres sional resistance and subsequent recovery properties (when the deforming forces are removed) of perpendicular-laid highlofts are compared to those made by conventional cross-laid technology. A simple thickness measurement instrument is used as a highloft compressibility gauge. The perpendicular-laid fabrics show higher compressional resis tance and their recovery properties are superior to those of cross-laid fabrics. Low cotton-content highlofts containing up to 20% cotton have a compressional behavior and dimensional stability similar to 100% synthetic fiber fabrics. These low cotton-content highlofts are economical to produce and have improved biodegradability.

With the objective of boosting ring spinning productivity, a new tandem spinning system combining air-jet and ring spinning technologies in continuous tandem is investigated. In this “air-plus-ring” tandem spinning system, a drafted roving strand as it emerges from the front roller nip feeds into a single- or dual-jet air nozzle where it is subjected to a vortex of compressed air, producing a pneumatically entangled, false-twisted, partially strengthened strand. This so-called prefabricated, air-bolstered strand continuously feeds into a standard ring spinning zone and is ultimately spun into a novel, single-component yarn. By spinning a few cotton and cotton-blend yarns with the lowest practical twist levels possible on both the tandem and conventional ring spinning systems, we show that a tandem spun yarn can be produced with a relatively lower (true ring) twist level than a pure ring spun yarn. To an extent, the tandem spinning's air-bolstering action reinforces the drafted fibrous strand, contributing to yarn formation and hence character. Since ring spinning productivity is inversely proportional to yarn twist level, the relatively lower twist level required in tandem spinning allows a proportionately higher yarn production speed (in some cases, up to 50% faster than the conventional ring spinning), while maintaining spindle speed at the traditional, optimum level imposed by the limiting traveler speed. Tandem spun yarns, however, are somewhat different from, and generally weaker than, conventional ring spun yarns. This paper briefly describes a prototype of the new tandem spinning system developed on a laboratory Spintester, and shows spinning parameters and properties of a few yarns produced on both the tandem arid conventional ring spinning systems, each employing the traditional (maximum) optimum spindle speed of 10,000 rpm for a given 5.0 cm (2 inch) diameter ring.