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:
1st 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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