Author：Baby & Adult Diaper Materials FROM：Diaper Materials Manufacturer TIME：2023-03-03
Spandex yarn is a fiber made of a block copolymer with polyurethane as the main component. It has the characteristics of large elongation, high elastic recovery rate, low elastic modulus and good fatigue resistance. This article introduces the reasons for the high elasticity of spandex yarn and the main varieties.
The high elasticity of polyurethane fiber is different from general elastic yarn, which is determined by the characteristics of polymer macromolecular composition and supramolecular structure. The soft segment is composed of aliphatic polyester or polyether, which can be regarded as an easily stretched spring; while the rigid segment is composed of urethane and urea groups, like a rigid ball. The net composed of small balls connecting the springs to each other is an elastic body with a certain strength. The two segments are linked together by a covalent bond. Because each single bond in the soft segment rotates in different degrees around its adjacent single bond, the long chain segment with curved shape is like a messy coil, and its shape is constantly changing. The macromolecules have great adaptability under the action of external force and the length also has great room for stretching, which endows the spandex yarn with the characteristics of high elongation and high elastic recovery.
The main varieties of spandex yarn include bare silk, core-spun yarn, covered yarn, and twisted yarn.
Bare silk is the earliest developed variety and can be used for processing without spinning. Due to the large friction coefficient and poor sliding properties of bare filaments, they are not used directly for weaving fabrics, and are generally suitable for interlacing with other chemical fiber filaments on knitting machines. The main textile products are tights, sportswear, leggings, surgical bandages, etc.
The most widely used variety of spandex yarn is core-spun yarn, which is a yarn spun with spandex as the core yarn and one or several non-elastic short fibers (cotton, wool, acrylic, polyester, etc.)
The core yarn provides excellent elasticity and the outer fibers provide the desired surface characteristics. Clothing fabrics such as wool core yarns not only have the appearance and warmth retention of general wool fabrics, but also stretch freely when worn.
Covered yarn is also called wrapped yarn. It is an elastic yarn formed by using spandex as the core and covering it with synthetic fiber filaments or yarns in a spiral manner. Covered yarn has a stiffer feel, thicker yarn, and thicker woven fabric. It is mainly used for elastic fabrics such as socks, elastic belts, and leggings.
The twisted yarn, also known as the ply yarn, is made by combining and twisting with two other inelastic yarns while drafting the spandex. The twisted yarn is mostly used for weaving thick and thick fabrics, and the hand is slightly hard.
Spandex yarn is a kind of high elastic synthetic fiber made of linear polymer substance containing more than 85% polyurethane segments. Knowing about spandex yarn will help people to better apply it.
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