Acrylic Yarns Research Articles

The effect of hot‐wet draw ratio on the coefficient of friction of wet‐spun acrylic yarns

AbstractA series of wet‐spun poly(acrylonitrile‐co‐vinyl acetate) yarns that were hot‐wet stretched to a draw ratio range of 2.0 × −7.0 × were made for study of surface morphology and frictional characteristics. These yarns show an increase in draw ratio. The fiber to fiber coefficient of friction, measured parallel (line contact), and perpendicular (point contact), increases with draw ratio, giving an excellent correlation between orientation and friction. The effects of hot‐wet draw ratio on the surface structure and its frictional behavior are discussed.

Acrylic Fiber Spinning with a Rotary Ring

This paper describes the results of the investigation of the possibility of high-speed and stable acrylic spinning with rotary rings. Results of the test are as follows:(1) The wear of travellers on the rotary ring is far less than that on the stationary ring.(2) At high-speed (15, 500rpm), yarn fluffs caused by the rotary ring are significantly less than those by the stationary ring.(3) Strength and elongation of single yarns produced by the rotary ring are superior to those by the stationary ring under certain spinning conditions (at 15, 500rpm and at the start of the spinning). But no significant difference is found under other conditions.(4) At high-speed rotating, melt yarn by the rotary ring is less than that by the stationary ring.(5) Yarn end-down and traveller fly-away with the rotary ring are significantly lower than those with the stationary ring.(6) The power consumption by the rotary ring does not differ from that by the stationary ring. From the above results, it is concluded that the rotaty ring is effective for high-speed spinning of acrylic yarns.

Influence of a Yarn Extractive Nozzle on the Apparent Loss of Twist in Rotor Open-End Acrylic Staple Spun Yarns

The influence of a yam extractive nozzle on the apparent loss of twist or "residual twist" has been studied for rotor open-end acrylic staple spun yarns. Four factors were studied: two quantitative factors - yam linear density at three levels and yarn twist multiplier at five levels, and two qualitative factors - three nozzle types and four rotor types. The analysis of results showed that both rotor type and extractive nozzle type exert a significant influence on residual twist, which tends to increase when the nozzle produces an increasing false twist effect on the yam and to decrease when yarn friction against the rotor increases. Residual twist increases significantly in a linear manner with both yarn linear density and twist multiplier. The nozzle type interacts significantly with all other factors (rotor type, yam linear density, and twist multiplier). An inter action between yarn linear density and twist multiplier has been also detected. Generally both nozzle type and twist multiplier exert a significant influence on the residual twist coefficient of variation.

Relation Between Twist and Abrasion Resistance of Rotor Spun Yarns

The relation between twist and abrasion resistance of polyester, polyester-cotton (50/50), and polyester-viscose (50/50) open end spun yarns was studied. The same trend observed in Part I of this study concerning cotton yams, viscose, and acrylic yarns is shown here. Abrasion resistance indefinitely increases with yarn twist (up to a twist multiplier of a = 200).

Developments in Package Dyeing

Progress in package‐dyeing yarn during the past ten years has been rapid, both in the total weight of yarn dyed, the types of fibre being dyed, and particularly in the design of dyeing machines and to a lesser extent in dyeing techniques. Polyester filament yarn is of great importance, but there have been significant developments in dyeing high‐bulk acrylic yarns. In machinery developments, the outstanding features are in the rate of flow of liquor, and the frequency with which the liquor is circulated. New techniques have been developed to take advantage of these mechanical features, so that dyeing can be commenced at 135°C and the liquor dropped at this temperature, thus minimizing oligomer problems with polyester yarn. Many new disperse dyes of high sublimination fastness on polyester fibre have been introduced and these take full advantage of the new machinery and dyeing techniques.Another factor leading to wider use of package dyeing has been the need for shorter manufacturing cycles in the production of coloured yarn, particularly for woven fabrics. Worsted yarn, which would normally have been spun from dyed top is now being package dyed on a large scale.With spun yarns, the advantages of dyeing acrylic yarn in muff form have led to the rapid growth of this method of dyeing.

Tensile properties of graphite fibers from several acrylic yarns: Ezekiel, H. M. Fibre Science and Technology, Vol 3, No 3, p 243 (1971)

Tensile properties of graphite fibers from several acrylic yarns: Ezekiel, H. M. Fibre Science and Technology, Vol 3, No 3, p 243 (1971)

Tensile properties of graphite fibers from several acrylic yarns

Graphite fibers have been made from acrylic yarns with chemically different compositions and with a wide range of tenacities and orientation. Fibers with moduli of elasticity above 60 million psi and tensile strengths above 250,000 psi could be formed from most of the yarns. The moduli of the graphite fibers from one of the yarns are shown to be substantially affected by graphitisation tensions and temperatures.

Density-Modulus Relationship in Graphite Fibers Made from Acrylic Yarns

Three types of polyacrylonitrile yarn were converted to graphite fibers. There was a linear relation between density and Young's modulus of the graphite fibers, the ranges observed being 1.58 to 2.18 grams per cubic centimeter and 25 to 112 x 10(6) pounds per square inch.

Package Dyeing of Continuous‐filament Nylon, Polyester and Acrylic Yarns

The various forms in which yarn is dyed in packages are considered. Package‐dyeing machines are then discussed. Techniques for the dyeing of continuous‐filament nylon, polyester and acrylic yarns are given. Mention is made of the drying of package‐dyed yarns and evaluation of the dyeing. Colour measurement has not yet proved to be an acceptable tool for the practical dyer, although it may eventually provide the required assistance. Detailed attention should be paid to the weighing of dyes and dyebath auxiliaries. Dye ranges should be extended for complex processes such as the package dyeing of continuous‐filament yarns.

Production of High‐bulk Acrylic Yarns by the Tow‐dyeing Route

Batches of high‐bulk acrylic yarns of up to 15,000 lb have been successfully produced by the tow‐dyeing route. The method of dyeing is described. The ‘atoz’ process is also described and the results obtained are discussed. Advantages of the method include: coloration is economical; the yarn is free from flattening, tangling and other disturbances; and fancy effects, such as marls, can be produced easily. Limitations include: it is not economic to produce quantities of less than 1000–1500 lb by the method; extreme care is required to avoid contamination of yarn with fibres of different colours; and considerable forward planning is necessary.

Fiber-to-Yarn Strength Translation of Acrylic Spun Yarns

A method is described for accurately determining the ultimate tenacity of an acrylic yarn and its fiber-to-yarn strength translation efficiency. Both of these values are essentially independent of the nonuniformity of the denier of the yarn. The method con sists of determining the denier of thin segments of yarn with the Uster Evenness Tester and then finding the tensile strength of these same yarn segments with the Instron Tensile Tester. Differences between ultimate yarn tenacities in these thin yarn sections and tenacities based on yarn skein and single-end strengths are also examined.

Dimensional Stability of High-Bulk Acrylic Knit Fabrics1

The dimensional stability of single jersey fabrics knitted from high-bulk acrylic yarns produced on the Turbo stapler is examined. Geometric changes occurring during bulking, and dimensional stability of the finished fabrics during machine-washing (120°F) and tumble-drying (165°F) are discussed in terms of Munden's theory of knit fabric stability. The effect of bulking under both relaxed conditions and with an along-wale tension of 0.003 g/den is described.

22—FACTORS AFFECTING THE THICKNESS AND COMPRESSIBILITY OF WORSTED-SPUN YARNS

Yarn-thickness measurements have been made on a range of worsted-spun yarns, apparatus being used whereby loads ranging from I to 100 g could be mechanically applied over a length of 0–5 cm of yarn. A linear relation was found when the logarithm of the load was plotted against the logarithm of the yarn thickness, and this has been used to provide a ‘thickness index’ and a ‘compression index’ for each yarn examined. It has been shown that the two most important factors influencing yarn thickness and compression are the spinning twist and the fibre crimp, these being followed closely by the fibre length. Large differences were observed between the thickness and the compression of yarns spun to the same linear density from a range of different wool qualities, and these were largely due to the combined influence of the fibre crimp, length, and diameter. Considerable increases in yarn thickness and compression were also found between acrylic fibre yarns before and after bulking. Factors exerting less influence...

Carpet Performance Evaluation

The Tetrapod Walker machine was evaluated as a device for the accelerated testing of carpets. Tufted carpets were prepared from wool, nylon, acrylic, and polypropylene yarns, in both cut-pile and loop-pile construction. Four levels of pile weight, obtained by varying the number of tufts per inch, were prepared for each carpet. The percentage loss in pile height resulting from exposure in the Tetrapod Walker was found to be a linear function of the logarithm of the number of revolutions of the Tetrapod Walker. This function was characteristic of each carpet. Specifications for a tentative test method were developed. The method involves measurement of the percentage decrease in pile height after exposure of the carpet sample to 50,000 revolutions (overnight operation) of the Tetrapod Walker. Studies on the compression and recovery properties of these carpets will be reported in a subsequent paper.

The Dimensional Stability of Acrylic Knit Fabrics

Fabrics knit from three different stable acrylic yarns have been examined for dimen sional stability both in the dry relaxed form and with length distortion. Three methods of wet relaxation were employed: wetting and drying at 115°C, immersion in boiling water, and tumble drying. While acrylic knit goods are similar to comparable goods knit from cotton or wool with respect to wet relaxation shrinkage, two important differences are demonstrated. First, the minimum temperature at which relaxation shrinkage occurs is well above room temperature. Secondly, the equilibrium loop shape is shown to be a function of the thermal history of the fabric.

HIGH-BULK ACRYLIC YARNS AND THEIR BEHAVIOUR IN WOVEN FABRICS

The essential principles underlying the use of bulked and textured yarns in woven fabrics are discussed in general terms and reference is made to some of the more important practical aspects of weaving and finishing. Factors affecting the bulking behaviour of the high-bulk acrylic yarns are considered in more detail, special emphasis being laid on the importance of yarn and fabric structure.

THE DYEING OF NEW YARNS AND FABRICS

The dyeing properties of the new synthetic fibres are reviewed under selection of dyes and the application of dyes, new techniques such as “carrier” dyeing and high-temperature dyeing being briefly described. The dyeing of novel yarns and fabrics made from these fibres is described, sections being devoted to high-bulk acrylic yarns, textured yarns, stretch yarns and novel woven fabrics. Particular emphasis is placed on the precautions that must be taken during the dyeing process in order to maintain the novel effects which have been inserted in the goods.