Study Unit 7: Manufactured non-cellulosic: polyamide NYLON

Question 1

History

Answer 1

The general public was first introduced to a truly synthetic fibre on 15 May 1940, when nylon stockings were launched after a successful mass advertising campaign. However, the history of nylon, started in 1927 when the DuPont Company decided to give a small group of scientists, under the leadership of Wallace Caruthers, unrestricted funds to do research into fibre development.

Question 2

Fibre properties

Answer 2

Nylon has a protein-like molecule and is related chemically to the protein fibres wool and silk. It is a more expensive fibre than polyester and is used in applications where its specific properties are needed. Fabrics may be fine and soft or firm, according to fibre fineness, fabric construction and finishing. Fibres can be matte or lustrous depending on fibre cross-section and additives.

Question 3

Physical structure

Answer 3

As with most other manufactured fibres, the length and diameter of nylon can be controlled. A wide range of cross-sections are produced, including, Y-shaped, trilobal, round, triangle, pentagonal and hollow. Filaments, textured filaments (about 80% of nylon filament production) and staple fibres are available.

Question 4

Properties relating to durability

1. Abrasion resistance

Answer 4

Nylon has excellent abrasion resistance. Nylon carpet fibres can outwear all other fibres.

Question 5

2. Strength

Answer 5

Nylon is a very strong fibre. It can have a tenacity between 31–45 cN/tex. Tenacity drops when the fibre is wet by about 10–20%.

Question 6

3. Flexibility

Answer 6

Nylon has good flexibility.

Question 7

4. Elongation

Answer 7

Nylon has high elongation (16% at break).

Question 8

Properties relating to comfort

1. Moisture absorption

Answer 8

Compared with natural fibres, nylon has rather low moisture absorption (moisture regain of about 3.5–5%). However, its regain is the highest for manufactured non-cellulosic fibres. Static can be a problem, particularly when the air is not humid.

Question 9

2. Heat conductivity

Answer 9

Nylon fibres are not good conductors of heat, but nylon fibres may or may not conduct heat well. Nylon can be made into very fine filaments which, if woven compactly, will result in a warm fabric. However, if extremely thin, lightweight, sheer fabrics are woven, they can be suitable for summer wear – though they are not as comfortable to wear as cotton and linen.

Question 10

Properties relating to appearance retention

1. Resiliency

Answer 10

Nylon has excellent resiliency and therefore recovers well from creasing, wrinkling or crushing.

Question 11

2. Dimensional stability

Answer 11

Nylon is thermoplastic. It can be heat set so that it will retain its shape during use and washing. High temperatures are used for heat setting. Application of temperatures higher than those used for heat-setting may cause fibre deformation, shrinkage or even melting.

Question 12

3. Elasticity

Answer 12

Nylon is a highly elastic fibre (82–89% at 3% stretch). This property makes it suitable for end-uses where stretch and recovery are important.

Question 13

Properties relating to care

1. Effect of alkalis

Answer 13

Alkalis have no effect on nylon.

Question 14

2. Effect of acids

Answer 14

Mineral acids will dissolve nylon or cause it to disintegrate. Nylon stockings have been known to disintegrate while being worn in industrial areas where acid fumes are present.

Question 15

3. Effect of sunlight

Answer 15

Sunlight causes gradual degradation of nylon. Therefore, it is not suitable for curtains.

Question 16

4. Biological properties

Answer 16

Mildew, bacteria or insects do not generally affect nylon.

Question 17

Durability

Answer 17

Excellent

Question 18

Abrasion resistance

Answer 18

Excellent

Question 19

Tenacity

Answer 19

Excellent

Question 20

Elongation

Answer 20

High

Question 21

Comfort

Answer 21

Low

Question 22

Absorbency

Answer 22

Low

Question 23

Heat conductivity

Answer 23

Moderate

Question 24

Appearance retention

Answer 24

High

Question 25

Resiliency

Answer 25

High

Question 26

Dimensional stability

Answer 26

High

Question 27

Elastic recovery

Answer 27

Excellent

Question 28

Care

Answer 28

Most items made from nylon can be machine washed
Warm water and a fabric softener to the final rinse cycle are recommended
Nylon tends to pick up colours from other items in the wash Wash white nylons separately to avoid a grey look
They can be hung out to dry (Nylon is quick drying) or tumble dried at low temperatures
Tumble drying can cause static build up
Remove articles from the dyer as soon as the cycle is completed
If ironing is required, use a warm iron. Safe ironing temperature 150 oC
Resistant to chlorine bleach

Question 29

End Uses

Answer 29

It is used in‘Dri-mac’-type jackets and tracksuits, linings, lingerie, blouses, dresses and socks.
 Its elastic recovery makes it suitable for hosiery (stockings), ski pants and swim suits.
 It is also used in luggage and carpets.
 It also has many industrial uses (eg belting, parachute fabric, cords, robes, netting, brush bristles, umbrellas and sporting goods).
Staple fibres are often used in blends with other fibres in these end uses.