Spandex | Properties, Manufacturing process | Uses

 

Spandex

Spandex

The term spandex is an anagram of the word ‘expands’, which is a familiar name in North America. In continental Europe, it is characterized by forms of 'elastane', including élasthanne (France), elastan (Germany, Sweden), elastano (Spain), elastam (Italy), and elastaan (Netherlands); And in the United Kingdom, Ireland, Portugal, Spain, Latin America, Australia, New Zealand, and Israel, it is commonly known as ‘Lycra’.

Spandex is a synthetic fiber known for its exceptional elasticity that is a polyether-polyurea copolymer that was invented in 1958 by chemist Joseph Shivers at DuPont's Benger Laboratory in Waynesboro, Virginia. Generically spandex is composed of at least 85 percent polyurethane by weight. These fibers are commonly used for their highly elastic properties. The trademarked fibers of this group are Lycra, Numa, Spandelle, and Vyrene. Such fibers substitute natural and synthetic rubber fibers for many textile purposes.

Properties of spandex

i. Spandex can be stretched repeatedly and is still found very close back to its original length and size

ii. It can be stretched generally more than 500% without breaking

iii. It is stronger, more durable, and has higher retractable strength than rubber

iv. It is lightweight, soft, smooth, supple fiber

v. It provides a combination of comfort and fit in garments, prevents bagging and sagging

vi. Heat-settable - Helps to convert baked fabrics into flat fabrics or flat fabrics into permanent round shapes

vii. These are dyeable

viii. It is resistant to corrosion by body oils, sweat, lotions, or detergents

ix. It is abrasion-resistant

x. Spandex fabrics are sewn, with little or no damage from needle cutting compared to older types of elastic materials.

xi. Available in fiber diameters ranging from 10 deniers to 2500 deniers

xii. It is available in clear and opaque lusters.

Spandex fabric


The manufacturing process of spandex

Spandex fibers are produced in four ways such as melt extrusion, reaction spinning, solution dry spinning, and solution wet spinning. The solution dry spinning method is popularly used to produce more than 94.5% of the world's spandex fibers. The process is-

A. 1st Step is to produce the pre-polymer

In this step, it mixes micro glycol with diisocyanate monomers. These are mixed in a reaction vessel to produce a pre-polymer. A common ratio of glycol and diisocyanate is 1: 2.

B. 2nd step is to produce the spinning solution

Pre-polymer reacts with equal amounts of di-amine. It is known as a chain extension reaction. The applied solution is mixed with a solvent to produce the spinning solution. The solvent helps to make the solution thinner and easier to handle and then it can be thrown into the fiber production cell.

C. 3rd step - the solution is pumped into a cylindrical spinning cell

The spinning solution is pumped into a tubular spinning cell where it is cured and converted into fibers form. In this chamber, the polymer solution is forced through a metal plate called a spinneret. This results in the solution being marginalized in the strands of the liquid polymer. As the strands pass through the cell they are heated in the presence of a nitrogen and solvent gas. This process results in the liquid polymer chemically reacting and forming a stiff strand.

D. 4th step is making fiber

As the fibers leave the cell, several strong strands bundle together to produce the desired thickness. Each of the fibers in the spandex consists of many individual fibers that adhere to each other due to the natural adhesion of their surface.

E. 5th step is to stick together and produce textiles

The resulting fibers are treated with a finishing agent that may be magnesium stearate or polymer. This treatment helps the fibers to stick together and produce textiles. The fibers are then transferred through a series of rollers in a spool.

Uses of spandex

i. It is used to support, shape, or mold the body or to keep textiles from stretching out of shape during use.

ii. It is used primarily in knit foundation garments, action wear, intimate apparel, shapewear, hosiery, furnishings, and narrow fabrics.

iii. It is used in medical-surgical and supports hoses, bandages, and surgical wraps.

iv. Blends of 2% to 40% spandex with other fibers is a common matter.

v. Spandex yarns are also possible to weave or knit.

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