Pneumatic splicing was examined for various yarns spun from different fibers on different spinning systems. The retention properties of the spliced yarns compared to normal yarn are discussed; the results indicate that wet splicing gives better property retention than dry splicing. Retention of yarn properties in decreasing order was for yarns spun from polyester, polyester-rich blends, viscose, cotton, and wool, respectively. Coarse yarn, particularly that spun on a ring spinning system, contributes the most to better spliced yarn properties.

An account is given of a study of the dimensional changes of plain weft knitted fabrics made from 12s, 16s, and 22s grasicrimp yam, brought about by various processes of relaxation including dry relaxation, wet relaxation, and tumble drying. In the dry relaxed state, the nature of knitted loop depends on the yarn's physical properties and knitting variables. After full relaxation, the values K c , K w , K s , and K c /K w are independent of yarn or machine variables and approach a constant. In the full relaxed state, fabric thickness is independent of the tightness factor and depends on yam diameter and twists. The angle of wale lines with the vertical is increased with the twist multiplier and further increases after wet relaxation. Fabric bulk depends on loop length in all states of relaxation and has a linear relationship with the tightness factor after full relaxation.

The structure of a splice made by a pneumatic splicer was investigated by studying the longitudinal view and cross sections of the splice zone. The splice has three distinct regions: twisting, wrapping, and tucking/intermingling. The strength of the splice is primarily due to the tucking/intermingling region. Wrapping preserves the splice and gives a clean appearance. Twisting provides lateral forces and reduces interfiber slippage in the tucking/intermingling zone.

The dimensional and mechanical properties of plain knitted fabrics from open-end and ring spun acrylic-viscose blended yams are investigated. The fabric area shrinkage (%), thickness, and areal density of open-end spun yarns are greater but the bursting strength is less in comparison to ring-spun yarns. Knitted fabrics from ring spun yarns have a greater propensity to pill.The technical and economic advantages of openend spinning, especially of rotor spinning, mean that more staple fibers are being converted into yarns by this method. This paper discusses the use of open-end spun yams for weft knitted fabrics.Rotor spinning of yarns for knitted fabrics has several advantages such as large package size with few knots or slubs or thick places, low linting, uniform strength and evenness, low hairiness, smooth fabric appearance, as well as some disadvantages such as stiffness and a consequent harsh handle. Bumip and Saha [2] have concluded that relaxation shrinkage in knits from OE spun cotton yams is greater than that of knits from ring-spun yarns. Black's results [ 1 show significant improvements in knitting performance of OE spun cotton yams compared to ring-spun yams. He also points out that although the bursting strength of OE fabrics is lower, it would pass existing standards. Cygan [3] has shown that knitted fabrics from rotor yarns have better pilling grades. He also mentions that rotor yarns can definitely be seen as an enrichment of the acrylic field. ExperimentalThe yams in this study were all made from a blend of 1.25d, 38 mm acrylic fiber (Cashmilon) and 1.5d, 38 mm viscose fiber (Grassilene). The sliver up to the drawing stage was prepared on a Shirley miniature card and draw-frame; the delivered sliver tex was 4473.5.The specifications for the ring and open-end spun yams are shown in Table I. The Sinker body hosiery knitting machine used to make the knitted fabric samples had the following specifications: 8.89 crri diameter, one feeder, machine rpm of 35, machine gauge used for 10's and 14's count of 15.0 and for 18's count of 22.8, and a total of 110 needles for 10's and 14's count and 167 needles for 18's count. The plain knitted samples were produced TABLE I. ..for rinaaad c~od spun ~ar~. with three different stitch lengths: minimum, medium, and maximum. RELAXATION TREATMENT Samples 1.5 meters long were used in these experiments. Dry RelaxationAfter knitting, all the samples were laid, free from constraints, on a flat surface and allowed to condition for at least 72 hours in a standard atmosphere of 65 ± 2% RH at 27 ± 2°C (as given in the ASTM standand). After dry relaxation, 10 cm X 10 cm squares were marked on the samples with waterproof ink. The samples were then wet relaxed and full relaxed, after which measurements were taken.

The contribution of the three different splice elements was studied. Splice strength is primarily due to intermingling/tucking. Twisting also contributes significantly to splice strength, but the contribution of wrapping to strength is minimal.