Tensile Recovery Behavior of Textile Fibers

The tensile properties of wool, mohair, human hair, casein, Vicara, and silk, including their behavior when knotted, after repeated stresses (mechanical conditioning) and when swollen in water were investigated. The immediate elastic recovery, the delayed recovery, and the permanent set of these fibers were measured by means of a cycling technique using the Instron tensile tester and the Sookne-Harris fiber extensometer. Actual and relative values of elongation components under different testing conditions are demonstrated graphically from the beginning of the stretching procedure up to rupture.Wool has an outstanding elastic recovery in the dry state, and its elastic behavior is improved after mechanical conditioning and when wet. Mohair and human hair, and to some extent casein and Vicara, have elastic properties similar to those of wool. The tensile behavior of silk is different, being characterized by considerable permanent set (dry and wet) and by high immediate elastic recovery after mechanical conditioning.WOOL is the most important protein fiber, and has a combination of extraordinary properties not found in any other natural, man-made, or synthetic textile material. The present study is confined to the tensile properties-i.e., tenacity, extensibility, and elastic recovery-of wool and other protein fibers. Major emphasis is placed on recovery, since the high resilience of wool is partly responsible for its outstanding performance [4]. The behavior of wool is compared to that of five other natural and regenerated protein fibers : mohair, human hair, casein, Vicara [5], and silk. These fibers are similar to wool in that they consist of long-chain protein molecules, although some differences exist in their chemical composition, crystallinity, and crystal structure, and they are also considerably different in morphology. The aim of the present study is to learn to what extent wool-like tensile properties are present in these closely related fibers. Test MethodsTensile tests were made using two instruments : the Instron tensile tester, Model TT-B [ l, 3 ] , and the Sookne-Harris fiber tester [7,8] . It is not surprising that results obtained by such different instruments deviate somewhat from each other, reflecting the particular conditions of the tests performed. These differences, however, were found to be relatively slight.The stress-strain properties of fibers were tested first under standard conditions at 70°F (21.1 °C) and 65 % relative humidity. A 5-in. (12.7 cm.) gage length and a jaw separation rate of 5 in. (12.7 cm.) per min., corresponding to 100% elongation of the specimen per min., were used for the Instron tensile tester.Since these conditions could not be duplicated in the Sookne-Harris tester, the longest practical gage length, 2.0 in. (5.1 cm.), and the highest jaw speed, 0.2 in. (0.51 cm.) per min., corresponding to 10% elongation of the specimen per min., were used.Stress-strain curves obtained under standard conditions reveal to only a limited extent the tensile behavior of fibers. Therefo...

Section: Recovery Behavior Of the Fibers Tested Behavior Of Wool Yarnmentioning

confidence: 83%

Section: Test Methodsmentioning

confidence: 99%

The Tensile Behavior of Some Protein Fibers

Susich¹,

Zagieboylo²

1953

“…. Compnny," Immediate and delayed recovery and permanent set were evaluated according to the method described by Susich [20]. Moisture contents and regains were determined hy a standard method [31.…”

Section: Methodsmentioning

confidence: 99%

Vacuum Cross-Linking of Chemically Modified Cotton

Soignet

Benerito

Pilkington

1969

Cottons containing carboxylic acid groups display good wrinkle recovery properties after the simultaneous application of heat and vacuum. This wrinkle recovery can be removed by soaking the fabric in dilute base which converts the acid to the carboxylate salt. To reintroduce the cross link, as shown by electron microscopy, it is first necessary to convert the salt to the free acid and then subject the fabric to the heat and vacuum treatment. Wrinkle recovery values can be further improved by first treating the cotton to introduce either primary or tertiary amine groups and then treating with chloroacetic acid to introduce the carboxyl groups. Wrinkle recovery imparted by heat and vacuum is stable to acid and neutral washes. The procedure can also be used to impart and remove creases in fabrics. Because of the prolonged heating, the fabric tends to discolor, but this discoloration can be removed by mild chlorine bleaching without affecting the wrinkle recovery.

“…Elastic Recovery Visco-elastic properties have been studied by various methods, including that described by Susich and Backer (22). The recovery behavior of greige tire cords, graphically represented in this manner, indicates that permanent set of the nylon 6 cord is lower than the corresponding values for a comparable 6,6 nylon cord, when measured at zero time or after two cycles with a 5-min, interval.…”

Section: Improvements In Nylonmentioning

confidence: 99%

Nylon 6—Current Developments

Nesty¹

1959

Epsilon polycaproamide (nylon 6), with more than twenty years' effort behind it in Europe, is now established as a commercial fiber in the U.S. Historically, its development goes back at least sixty years, when it narrowly missed becoming the first truly man-made fiber. Although the molecular structure of nylon 6 is almost identical to that of nylon 6,6, its melting point is lower, probably due to special entropy considerations. Thus nylon 6 permits easier and more economical thermal processing. Thermal properties of the two nylons, even when both are modified with antioxidants, are seen to be similar in many respects, but the 6 type has more resistance to thermal creep at high loads and is more stable with respect to end-group changes. A major domestic producer has developed technology solving the old problem of excessive monomer content without resorting to washing of yarn. Properties, applications, and current developments of various forms of nylon 6 fibers are described. A large potential is shown to exist for expanded use of this versatile fiber.