What is Spandex(LYCRA)??????

Lycra Fiber

Lycra Fabric

Spandex:


Spandex or elastane is a synthetic fiber known for its exceptional elasticity. It is strong, but less durable than its major non-synthetic competitor, natural latex. It is a polyurethane-polyurea copolymer that was invented in 1959 by chemists C. L. Sandquist and Joseph Shivers at DuPont's Benger Laboratory in Waynesboro, Virginia. When first introduced, it revolutionized many areas of the clothing industry.
The name "spandex" is an anagram of the word "expands". It is the preferred name in North America; in continental Europe it is referred to by variants of "elastane", i.e. elasthanne (France), elastan (Germany), elastano (Spain and Portugal), elastam (Italy) and Elasthaan (Holland), and is known in the UK, Ireland, Argentina, Australia and New Zealand primarily as Lycra. Brand names for spandex include Lycra (made by Koch subsidiary Invista, previously a part of DuPont), Elaspan (also Invista), Acepora (Taekwang), Creora (Hyosung), ROICA and Dorlastan (Asahi Kasei), Linel (Fillattice), and ESPA (Toyobo).


Spandex fibers production: 


Spandex fibers are produced in four different ways: melt extrusion, reaction spinning, solution dry spinning, and solution wet spinning. All of these methods include the initial step of reacting monomers to produce a prepolymer. Once the prepolymer is formed, it is reacted further in various ways and drawn out to make the fibers. The solution dry spinning method is used to produce over 94.5% of th.



 Solution dry spinning: 


Step 1: The first step is to produce the prepolymer. This is done by mixing a macroglycol with a diisocyanate monomer. The two compounds are mixed in a reaction vessel to produce a prepolymer. A typical ratio of glycol to diisocyanate is 1:2.[2]
Step 2: The prepolymer is further reacted with an equal amount of diamine. This reaction is known as chain extension reaction. The resulting solution is diluted with a solvent (DMAc) to produce the spinning solution. The solvent helps make the solution thinner and more easily handled, and then it can be pumped into the fibre production cell.
Step 3: The spinning solution is pumped into a cylindrical spinning cell where it is cured and converted into fibres. In this cell, the polymer solution is forced through a metal plate called a spinneret. This causes the solution to be aligned in strands of liquid polymer. As the strands pass through the cell, they are heated in the presence of a nitrogen and solvent gas. This process causes the liquid polymer to react chemically and form solid strands.
Step 4: As the fibres exit the cell, an amount of solid strands are bundled together to produce the desired thickness. Each fibre of spandex is made up of many smaller individual fibres that adhere to one another due to the natural stickiness of their surface.[2]
Step 5: The resulting fibres are then treated with a finishing agent which can be magnesium stearate or another polymer. This treatment prevents the fibres' sticking together and aids in textile manufacture. The fibres are then transferred through a series of rollers onto a spool.
.
Major spandex fibre uses: 

Apparel and clothing articles where stretch is desired, generally for comfort and fit, such as:

• activewear
• athletic, aerobic, and exercise apparel
• belts
• bra straps and side panels
• competitive swimwear
• cycling jerseys and shorts
• dance belts worn by male ballet dancers and others
• gloves
• hosiery
• leggings
• netball bodysuits
• orthopaedic braces
• rowing unisuits
• cross country race suits
• ski pants
• skinny jeans
• slacks
• miniskirts
• socks and tights
• swimsuits/bathing suits
• underwear
• wetsuits
• zentai

Compression garments such as: 

• foundation garments
• motion capture suits

Shaped garments such as: 

• bra cups
• support hose
• surgical hose
• superhero outfits
• women's volleyball shorts
• wrestling singlets
• Home furnishings, such as microbead pillows

Conclusion: 

For clothing, spandex is usually mixed with cotton or polyester, and accounts for a small percentage of the final fabric, which therefore retains most of the look and feel of the other fibers. In North America it is rare in men's clothing, but prevalent in women's. An estimated 80% of clothing sold in the United States contained spandex in 2010.

Description about count..

Yarn count/Yarn number/Linear density

Yarn count:

Count is a numerical expression which defines its fineness or coarseness.

Definition (given by Textile Institute):

“Count: A number indicating mass per unit length or length per unit mass of yarn.”

 

Yarn numbering/counting  systems:

There are two basic systems of yarn numbering:

1.     Direct system (mass per unit length)

2.     Indirect system (length per unit mass)

1.Direct system:

In a direct yarn counting system count is the weight of a unit length of yarn.

Let,

N= Yarn number or count

W= Weight of sample

L= Length of the sample

l= unit of length of the system

Then,

N =     W x l

              L

Example of direct systems: Tex, millitex, kilotex, Denier, Jute etc

 

2.Indirect system:

In an indirect yarn counting system count is the unit of length per unit of weight of yarn.

Let,

N= Yarn number or count

W= Weight of sample

L= Length of the sample

l= unit of length of the system

w= unit of weight of the system

Then,

N =     Lxw     

            lxW

Example of indirect systems: Cotton (Ne), Metric (Nm), Worsted etc

Table -1: Unit of Length & Weight(mass) in Direct counting system

Name of the System	Unit of mass	Unit of length
Tex	gm	km
Denier	gm	9km
Jute	Pound(lb)	14,400 yards (spyndle)

 

Table -2: Unit of Length & Weight(mass) in indirect counting system:

Name of the System	Unit of length	Unit of mass
Cotton (British or English)	840 yards(hank)	Pound(lb)
Metric	km	kg
Worsted	560 yards (hank)	Pound (lb)

 

Problems:

Problem-1:  If a skein of 100 m of filament yarn weighs 1.67 gm. Caculate its denier.

Problem-2:  A lea (120yd) of cotton yarn weighs 25 grains, calculate its count in the cotton system.

 

Definitions:

#Examples for indirect system:

Cotton count(Ne): It is defined as the length in hank of 840 yds per pound of yarn.

30 Ne: It is defined as the 30 hank (840x30 yds) of length per pound of yarn.

#Examples for indirect system:

Tex: It is defined as the weight in grams per km of yarn.

Millitex: It is defined as the weight in milligrams per km of yarn.

Kilotex: It is defined as the weight in kilograms per km of yarn.

10 tex: It is defined as 10 gm of weight per km of yarn.

110 denier: It is defined as 110 gm of weight per 9 km of yarn.

Count Conversion from one system to another

 

Count conversion from one system to another is achieved by conversion factors & constants.

 

1. Conversion from Direct to direct system

1. Conversion from Indirect to Indirect system

1. Conversion from Direct to indirect system

1. Conversion from Indirect to direct system

 

 

 

 

For 1 & 2 : A multiplying conversion factor is used

Unknown count = Multiplying conversion factor x Known count

 

For 3 & 4: A constant is used into which the known count is divided to give the equivalent count in the other system

Unknown count = Constant ÷ Known count

  

 

 

   Direct to direct:

Known yarn count in	Multiplying factor for unknown count in
	Tex	Denier
Tex	…	9
Denier	0.1111	...
Jute	34.45	310

 

Example:    Denier = 9 x Tex

                                Tex = 34.45 x Jute count

 

 

  Indirect to indirect:

Known yarn count in	Multiplying factor for unknown count in
	Metric (Nm)	Worsted
Cotton (Ne)	1.7	1.5

 

Example:    Worsted count = 1.5 x Cotton count

 

 

   Direct to indirect & Indirect to direct:

Known yarn count in	constant into which the known count is divided to give the equivalent count in the other systems
	Tex	Denier
Cotton (Ne)	590.5	5315
Metric (Nm)	1000	9000

 

Example:   Denier = 5315 ÷ Ne

              Tex = 590.5 ÷ Ne

 

Problem-1: Find denier count when Cotton count is 32 Ne & Tex is 10.

Relation between Yarn diameter & count:

Let,

       Yarn count = N tex

       Length of N gm yarn = 1000 m = 1000 x 100 cm = 10⁵ cm

ð    Length of 1 gm yarn =  10⁵     cm

                                                      N

Assuming,

       The specific volume of yarn = 1.1        [by experiment, an apparent specific volume of 1.1 for

                                                                          cotton was found]

       Volume of 1 gm yarn = 1.1 cm³

Length of 1.1 cm³ yarn =  10⁵     cm

                                                    N

We know,

      Volume = cross-sectional area x length

ð  1.1  =    πd²  x   10⁵                                  

                           4            N

ð  d²  =    4 x 1.1 x N         [d = diameter of yarn]                         

                           π x 10⁵

ð

d  =    0.375  x N     (cm)

                        100

ð d  ∞ N  (cm)      [For Direct system]

Now, converting the diameter in inches & tex to cotton count (Ne)

ð  d    =       0.375   x   590.5    x      1               (inch)

                               100           Ne             2.54

 

                    =           3.6                       (inch)

                           100Ne

ð d  =        1           (inch)

                     28Ne

ð d  ∞       1             (inch)     [For Indirect system]

                    Ne

Ways/methods of Count measurement

1.      Wrap reel & analytical balance

2.      Wrap reel & a Knowles balance

3.      Wrap reel & a quadrant balance

4.      Direct reading count balance

5.      Beesley’s balance ( special balance when small amount of samples available for

                                          testing)

Yarn count calculation for a doubled yarn:

Suppose a twofold cotton yarn i.e., a yarn made by twisting two single yarns together, the doubling process causes a contraction in the length of the component threads.

In an indirect system-

1/N = 1/N₁ +1/N₂

Here,

N= Resultant count (count of the doubled yarn)

N₁=N₂ = component thread count (after doubling process)

 

The effect of contraction due to doubling process cause the single yarns to become coarser-

Let,

N₁’ =N₂’= original count of the single yarn [before doubling process]

Then,

N₁’ = N₁ x (p+100)/100            [p=percentage of contraction in the length of the component threads]

 

Yarn count/Yarn number/Linear density

Yarn count:

Count is a numerical expression which defines its fineness or coarseness.

Definition (given by Textile Institute):

“Count: A number indicating mass per unit length or length per unit mass of yarn.”

 

Yarn numbering/counting  systems:

There are two basic systems of yarn numbering:

1.     Direct system (mass per unit length)

2.     Indirect system (length per unit mass)

1.Direct system:

In a direct yarn counting system count is the weight of a unit length of yarn.

Let,

N= Yarn number or count

W= Weight of sample

L= Length of the sample

l= unit of length of the system

Then,

N =     W x l

              L

Example of direct systems: Tex, millitex, kilotex, Denier, Jute etc

 

2.Indirect system:

In an indirect yarn counting system count is the unit of length per unit of weight of yarn.

Let,

N= Yarn number or count

W= Weight of sample

L= Length of the sample

l= unit of length of the system

w= unit of weight of the system

Then,

N =     Lxw     

            lxW

Example of indirect systems: Cotton (Ne), Metric (Nm), Worsted etc

Table -1: Unit of Length & Weight(mass) in Direct counting system

Name of the System	Unit of mass	Unit of length
Tex	gm	km
Denier	gm	9km
Jute	Pound(lb)	14,400 yards (spyndle)

 

Table -2: Unit of Length & Weight(mass) in indirect counting system:

Name of the System	Unit of length	Unit of mass
Cotton (British or English)	840 yards(hank)	Pound(lb)
Metric	km	kg
Worsted	560 yards (hank)	Pound (lb)

 

Problems:

Problem-1:  If a skein of 100 m of filament yarn weighs 1.67 gm. Caculate its denier.

Problem-2:  A lea (120yd) of cotton yarn weighs 25 grains, calculate its count in the cotton system.

 

Definitions:

#Examples for indirect system:

Cotton count(Ne): It is defined as the length in hank of 840 yds per pound of yarn.

30 Ne: It is defined as the 30 hank (840x30 yds) of length per pound of yarn.

#Examples for indirect system:

Tex: It is defined as the weight in grams per km of yarn.

Millitex: It is defined as the weight in milligrams per km of yarn.

Kilotex: It is defined as the weight in kilograms per km of yarn.

10 tex: It is defined as 10 gm of weight per km of yarn.

110 denier: It is defined as 110 gm of weight per 9 km of yarn.

Count Conversion from one system to another

 

Count conversion from one system to another is achieved by conversion factors & constants.

 

1. Conversion from Direct to direct system

1. Conversion from Indirect to Indirect system

1. Conversion from Direct to indirect system

1. Conversion from Indirect to direct system

 

 

 

 

For 1 & 2 : A multiplying conversion factor is used

Unknown count = Multiplying conversion factor x Known count

 

For 3 & 4: A constant is used into which the known count is divided to give the equivalent count in the other system

Unknown count = Constant ÷ Known count

 

 

 

 

 

 

 

 

 

 

 

 

   Direct to direct:

Known yarn count in	Multiplying factor for unknown count in
	Tex	Denier
Tex	…	9
Denier	0.1111	...
Jute	34.45	310

 

Example:    Denier = 9 x Tex

                                Tex = 34.45 x Jute count

 

 

  Indirect to indirect:

Known yarn count in	Multiplying factor for unknown count in
	Metric (Nm)	Worsted
Cotton (Ne)	1.7	1.5

 

Example:    Worsted count = 1.5 x Cotton count

 

 

   Direct to indirect & Indirect to direct:

Known yarn count in	constant into which the known count is divided to give the equivalent count in the other systems
	Tex	Denier
Cotton (Ne)	590.5	5315
Metric (Nm)	1000	9000

 

Example:   Denier = 5315 ÷ Ne

              Tex = 590.5 ÷ Ne

 

Problem-1: Find denier count when Cotton count is 32 Ne & Tex is 10.

Relation between Yarn diameter & count:

Let,

       Yarn count = N tex

       Length of N gm yarn = 1000 m = 1000 x 100 cm = 10⁵ cm

ð    Length of 1 gm yarn =  10⁵     cm

                                                      N

Assuming,

       The specific volume of yarn = 1.1        [by experiment, an apparent specific volume of 1.1 for

                                                                          cotton was found]

       Volume of 1 gm yarn = 1.1 cm³

Length of 1.1 cm³ yarn =  10⁵     cm

                                                    N

We know,

      Volume = cross-sectional area x length

ð  1.1  =    πd²  x   10⁵                                  

                           4            N

ð  d²  =    4 x 1.1 x N         [d = diameter of yarn]                         

                           π x 10⁵

ð

d  =    0.375  x N     (cm)

                        100

ð d  ∞ N  (cm)      [For Direct system]

Now, converting the diameter in inches & tex to cotton count (Ne)

ð  d    =       0.375   x   590.5    x      1               (inch)

                               100           Ne             2.54

 

                    =           3.6                       (inch)

                           100Ne

ð d  =        1           (inch)

                     28Ne

ð d  ∞       1             (inch)     [For Indirect system]

                    NeWays/methods of Count measurement

1.      Wrap reel & analytical balance

2.      Wrap reel & a Knowles balance

3.      Wrap reel & a quadrant balance

4.      Direct reading count balance

5.      Beesley’s balance ( special balance when small amount of samples available for

                                          testing)

Yarn count calculation for a doubled yarn:

Suppose a twofold cotton yarn i.e., a yarn made by twisting two single yarns together, the doubling process causes a contraction in the length of the component threads.

In an indirect system-

1/N = 1/N₁ +1/N₂

Here,

N= Resultant count (count of the doubled yarn)

N₁=N₂ = component thread count (after doubling process)

 

The effect of contraction due to doubling process cause the single yarns to become coarser-

Let,

N₁’ =N₂’= original count of the single yarn [before doubling process]

Then,

N₁’ = N₁ x (p+100)/100            [p=percentage of contraction in the length of the component threads]

 

contact: kazimurad_bd@yahoo.com