Physical Properties Of Spandex

Synthetic fibers with high breaking elongation (400% +), low modulus and high elastic recovery rate. Chinese trade name for multi-block polyurethane fiber. Also known as elastic fiber. Spandex has high elongation (500% ~ 700%), low elastic modulus (200% elongation, 0.04 ~ 0.12g/denier) and high elastic recovery rate (200% elongation, 95% ~ 99%). In addition to greater strength, other physical and mechanical properties are very similar to natural latex silk. It is more resistant to chemical degradation than latex filament, has moderate thermal stability, softening temperature of about 200℃ or more. Most dyes and finishing agents used for synthetic and natural fibers are also suitable for dyeing and finishing spandex. Spandex is resistant to sweat, seawater, and various dry washes and most sunscreens. Long-term exposure to sunlight or chlorine bleach will also fade, but the degree of fading varies greatly depending on the type of spandex.
Spandex has such high elasticity because its polymer chain is composed of a low melting point, amorphous "soft" chain segment for the parent and embedded in the high melting point, crystalline "hard" chain segment. A network structure is formed between the molecular chains of the flexible chain with a certain crosslinking. Due to the small interaction force between the molecular chains, it can be freely expanded and expanded, resulting in large elongation performance. The molecular binding force of the rigid chain segment is relatively large, and the molecular chain will not extend indefinitely, resulting in high resilience. Most of the cross sections of Radon filaments are dog-bone-shaped, while some filaments have smooth or jagged surfaces. The breaking strength is the lowest in all textile fibers, only 0.44 ~ 0.88CN/dtex (the strength of polyether type is higher than that of polyester type). The hygroscopicity range is small, generally 0.3-1.2% (the hygroscopicity of the compound wire is slightly higher than that of the monofilament). Heat resistance varies greatly depending on the variety, most fibers are stored in the range of 90 ~ 150 ° C for a short time, the fibers will not be damaged, the safe ironing temperature is below 150 ° C, and can be heated and wet washed. The dyeing performance is better, can be dyed into a variety of colors, the dye has a strong affinity for the fiber, can adapt to the vast majority of varieties of dyes, and has good chemical resistance, resistance to most of the acid and alkali, chemical agents, organic solvents, dry cleaning agents and bleach, as well as sun and snow resistance, but not resistant to oxides, easy to make the fiber yellow and strength reduced.