Synthetic Yarns Research Articles

42—THE STRETCH AND RECOVERY BEHAVIOUR OF ELASTOMERIC YARNS

The elastic properties of several polyurethane yarns and a natural-rubber filament have been measured. Part 1 of the paper deals with the behaviour of the materials in the condition in which they were supplied. In Part 2, the properties of the materials after thermal treatments at various temperatures within the range 20–220°C are presented and discussed. Thermal treatment is shown to have a pronounced effect on the stress-strain behaviour of the synthetic yarns, measured relative to their set dimensions, and on the retractive stress at a given extension. The elastic recoveries of the yarns are improved, their breaking extensions increased, and their strengths slightly decreased after thermal treatment. Relative to the synthetic yarns, thermal treatment has only a small effect on the elastic properties of rubber.

Gyroscopic Whirl of a Rotating Bobbin Mounted on a Swing-Arm

A bobbin mounted transversely at one end of a flexible arm which is pivoted at the other end, is represented by four degrees of freedom. The frequency equation is derived in non-dimensional form and changes in the frequencies of free vibration due to gyroscopic effects are discussed. Four of a possible 20 sets of frequency curves are illustrated. The analysis was prompted by vibration of a machine for winding synthetic yarn.

合繊フィラメント糸の高速増撚におけるリングとトラベラーについて

目的 近年ますます高速化を要求されつつある合繊フィラメント糸の増撚において, リング, トラベラー方式による高速撚糸とこれにともなう問題点を明らかにするため, これまでの応用実験結果と実用状況を総合して報告する. 結果 (1) 最適リングとトラベラーの形状は, スモールコニカル形の自動給油リング (V6Hh形) とHBC形トラベラーであり, 120mmφ8000rpm以上の高速撚糸において, 従来のフランジ高さ9.5～11.1mmのバーチカル形リングより秀れている. (2) 撚糸張力平均値を, デニール当りの大きさで制限した場合の最高スピンドル回転速度は, 細デニール糸においては, 軽量トラベラーの制約を受け, 太デニール糸においては可能な最大バルーニング径とその制御方法に制限される.そしてスモールコニカルリングと適合するトラベラーを用いることにより現在での実用スピンドル回転速度より20%の増加が可能である. (3) 今後の問題として, 糸質の向上, 糸とトラベラーの摩擦の減少および, バルーンストレッチの調整とその制御方法の改善などにより, リングとトラベラーの摩擦, 摩耗の面より定まる性能限界まで高速化を進めることができると考えられる.

MECHANICAL BEHAVIOR OF CRIMPED SYNTHETIC YARN

Strain recovery behaviour after static elongation was investigated on crimped synthetic yarns, when constant rate elongation was applied to the yarn.Residual strain decreases gradualy after elongation is reversed. Irreversible strain depends on the rate of elongation and on the applied elongation. Highest recovery was observed for the yarn on the applied elongation, prepared by the stuffer-box method, and the lowest for the one prepared by the conventional-twist method when ts, recovery time, is small. However, the differences of the recovery behaviour among yarns prepared by different methods become small when ts is large. The relation between after-effect- stress and residual strain is approximately linear in each yarn. The gradient of the liner relation is reciprocals of elasticity of relaxation element.

MECHANICAL BEHAVIOR OF CRIMPED SYNTHETIC YARN (2)

Load-elongation curve of a crimped synthetic yarn is divided into three regions. At the 1st region the crimps of filaments are only stretched. At the 2nd region, because the yarn is consisted of crimped filaments and filaments crimps are stretched to the true length, the filaments themselves are stretched. At the 3rd region, the filaments are themselves stretched.In this paper the load-elongtion behavior and stress relaxation at the 2nd region only will be investigated.The distribution of true length of the crimped filaments is a normal distribution. Their standard deviation ρ and mean value μ are dependent on the kinds of crimped yarns.It is easily understood that theoretical load-elongation curve is formed of standard normal distribution and stress curves of a crimped monofilament. Investigating the stress of crimped yarn theoretically, following equation may be derived;(1)where σi=stress of crimped monofilament at the 1st region.σi=stress of crimped monofilament at the 3rd region.f(εi)=probability density of distribution of true length at εi.f(εj)=probability density of distribution of true length at εj.The range of distribution of the true length for each crimped yarns is to be determined by their values of ρ max., ρ min., μ max., and μ min. Therefore by comparison of the theoretical curve and experimental curves, the identification of these curves are proved.At the second region relaxation stress is also divided into two parts, as in load-elongation behavior. One part is relaxation stress at crimp region, and the other part is at the true lengthed region. Stress relaxation may be expessed by the equation;(2)where σRi=relaxation stress for a monofilament at 1st region.σRj=relaxation stress for a monofilament at the 3rd regionRelation of quantity of relaxation stress up to a difinite time (such as 10sec) and elongation is non-linear.Because it is reasonable that difference of relaxation modulus is also non-linear to elongation, at the 1st region of elongation, relaxation modulus exhibits mainly linear property. But at the 2nd region, it is non-linear. At the third region it is also linear.

Limitations of synthetic fabrics as peritoneal substitutes.

The use of foreign substances to reinforce hernial repairs is almost commonplace today. Most popular among these materials are mesh screens of tantalum or steel and cloths made of synthetic yarns, such as Fortisan, nylon, and Dacron. In addition to their immediate function as structural supports, these substances further strengthen the closure by becoming enmeshed in fibrous tissue as time goes along. It is well known that no foreign substance is as well tolerated as the host's own tissues. Adequate surgical repair of some defects, however, is possible only with the use of substitute materials. Occasionally in clinical surgery it is necessary for the patch of foreign substance to come in direct contact with the serosal surfaces of underlying bowel, as, for example, after extensive resection of the diaphragm, pelvic peritoneum, or all abdominal-wall layers for malignancy, or when mural structures cannot be approximated for other reasons. No material has

A REVIEW OF DEVELOPMENTS IN THE PROPERTIES, PROCESSING AND UTILISATION OF MAN-MADE FIBRES

This paper reviews developments as follows. The production and consumption of man-made fibres in categories of the older rayon yarns and staple fibres, and the newer polyamides, polyesters and acrylics, with comparisons drawn between production, consumption and prices for the years 1938 and 1954/55. Some of the developments in the methods of manufacture of man-made fibres and the increasing range and properties of fibrous materials available. The improvements and developments in techniques and machinery for processing man-made yarns and staples, including sizing and yarn preparation, spinning, knitting, weaving, dyeing and finishing. Developments in dyeing and finishing to cope with the increasing variety of regenerated and synthetic yarns and staple fibres now available. Also, the dyeing and finishing of blends of these fibres with each other and with natural fibres.

The Tensile Properties of Man-Made and Synthetic Staple Yarns

The stress-strain properties, the tensile-recovery behavior, and the response to re peated tensioning (cycling) of sixteen staple yarns were investigated. Three man-made (Fiberglas, viscose, acetate) and seven synthetic (nylon, Orlon,2 Dacron,3 Dynel, Saran, polyvinyl chloride, Kuralon) textile materials were tested at standard conditions using the Instron Tensile Tester. The tensile recovery was obtained by measuring the three elongation and work com ponents. The total work of rupture was divided into the immediately recoverable work, creeping work, and unrecoverable work absorption. Dynamic tests were carried out by extending the yarns in 50 cycles to 80% of their elongation at break and measuring their response during and after this procedure. A comparison was made between tensile properties of staple yarns and corresponding multifilaments of the same material. Cycling tests were found useful in evaluating those tensile characteristics which are significant for the performance of yarns in service. It was attempted to interpret the behavior of yarns in repeated tensioning and flex abrasion from their known tensile properties.

Vinyl and Related Polymers: Their Preparations, Properties, and Applications in Rubbers, Plastics, Fibers, and in Medical and Industrial Arts.

Despite the words "medical... arts" in the subtitle, there is little in this excellent monograph to interest the physician. A few brief qualitative statements are made about toxicities of some of the monomers and of two types of polymers (orlon® [a new synthetic yarn] and polyisobutylenes). Several pages are devoted to methyl methacrylate dentures and to solutions of plastics as possible substitutes for blood plasma. On the other hand, the rest of the subtitle is correct and the author has done a superb job of reviewing the world literature (patent, periodical, trade, and military), organizing his material, presenting it for the general technical reader, illustrating it, and indexing it. Many persons will be glad to have access to the trade names of so many plastics, synthetic rubbers, and synthetic fibers. The printing is excellent.

Rayon and synthetic yarn handbook. By Dr. E. W. K. Schwarz and H. R. Mauersberger. 2nd enlarged ed. Pp. lii + 558. New York: Rayon Publishing Corp., 1936. $4.50

Journal of the Society of Chemical IndustryVolume 55, Issue 18 p. 343-343 Review Rayon and synthetic yarn handbook. By Dr. E. W. K. Schwarz and H. R. Mauersberger. 2nd enlarged ed. Pp. lii + 558. New York: Rayon Publishing Corp., 1936. $4.50 First published: 1 May 1936 https://doi.org/10.1002/jctb.5000551820AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume55, Issue181 May 1936Pages 343-343 RelatedInformation

Some Dynamic Properties of Filamentous Materials

A testing apparatus is described in which the chain-weight principle is used for the purpose of a slow and continuous load application as well as load removal. The elongation can be read with precision with the aid of a micrometer device and an indicator which has an attachment for practically eliminating parallactic errors. Readings are taken in the state of substantial equilibrium of load-versus-extension. With this machine it is possible to give special consideration to such critical points as the yield point. The instrument lends itself readily, furthermore, to the determination of hysteresis loops and also to the investigation of crimp in yarns. Reliable data are given of load extension curves of representative synthetic yarns. In addition to taking the stretch-versus-tension diagrams, as such, the hysteresis loops are determined for various points of the loadstrain curve and their theoretical and practical importance is discussed. The measurements taken of textile yarns are compared to the load extension characteristics of metals and the results are discussed in exact physical terms. The dynamic characteristics of sized yarn are discussed. The limitations of crimpage measurements are mentioned.