what is spandex fiber and spandex fiber properties

Spandex is a lightweight synthetic fiber. It is made up of a long chain polymer called polyurethane which is

produced by reacting a polyester with a disocyanate. The polymer is converted into a fiber using a dry spinning technique.

Step-1:

1^st step is to produce the propolymer. This is done by mixing a macro glycol with a diisocyanate monomer. The two compounds are mixed thgether in a reaction vessel to produce a prepolymer. The ratio of glycol and diisocyangate is 1:2.

Step-2:

They the polymer reacts with equal amount of diamine. The reaction is known as chain extension reaction. It is also known as spinning sol.

Step-3:

The spinning sol is pumped into a cylindrical spinning cell named spinnerate. The polymer so is forces through the spinnerate, then they are heated in the presence of nitrogen and solvent gas as the liquid polymer reacts.

Step-4:

The fiber exit the spinnerate an amount of solid strands are bundle together to produce the desired thickness. then the filaments are treated with finishing agent such as magnesium separate or other polymer. The fiber are then transferred to a series of theirs of roller onto a spool. Spandex fiber is bng-chain synthetic polymer. It is composed of 85% by weight of segmented polyurethane.the segmented structure of spandex filament contains two-phase domain morphology. One is soft segment is responsible for flexibility, expansion cold and thermal stability.

Property of spandex:

The greatest property of spandex filament is elasticity. They have 99% recovery at 200% extension. The metting point is about 232℃. Yellowing and loss of strength occurs with prolong exposure to sunlight and acid fumes in the air. The use of heat is the major care concern when spandex is part of the fabric. Cold water washing is easy, but repeated use of a hot dryer will deteriorate the fiber. Choiring bleach should never be used. lorning temperature should not exceed 149℃ on a hand iron. Long time ironing fiber will be degrate.

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