Page 99 - Advances in Textile Biotechnology

80 Advances in textile biotechnology

Table 4.1 Examples of polyamide compositions (adapted from Yang, 1989)
Nylon-6,10 —[—NH—(CH 2 ) 6 —NH—CO—(CH 2 ) 8 —CO—]—
Nylon-6 —[—NH—(CH 2 ) 5 —CO—]—
Nylon-11 —[—NH—(CH 2 ) 10 —CO—]—
Nylon-6,T —[—NH—(CH 2 ) 6 —OCO—(C 6 H 4 )—OCO—]—
mX,D,6 —[—NH—CH 3 (C 6 H 3 )—NH—CO—(CH 2 ) 4 —CO—]—
Nylon-6,6–6,10 —[—NH—(CH 2 ) 6 —NH—{—CO—(CH 2 ) 4 —CO—} 60 ={—CO—
(60 : 40) (CH 2 ) 8 —CO} 40 —]—

in which the linkage of the molecules occurs through the formation of the
amide groups. Polyamides may be made from a dicarboxylic acid and a
diamine, or from an amino acid or its lactam that is able to undergo self-
condensation. One of the most common polyamides, nylon 6.6, is produced
by the interaction of hexamethylenediamine and adipic acid. When ε-
caprolactam is the starting material, nylon 6, which consists more than 100
units of 6-aminohexanoic acids is obtained. Examples of polyamide com-
positions are presented in Table 4.1, but this chapter will emphasize the

modification of nylon 6.6 fi bres.

Polyamide properties and applications
The high strength, elasticity, lustre, abrasion resistance, dyeability and
shape-holding characteristics of nylon make it suitable for many applica-
tions. In clothing and home furnishings, nylon is an important fi bre, espe-
cially in socks, stockings, lingerie, stretch fabrics, sporting goods, carpets,
luggage, and materials used in upholstering of furniture. Industrial uses of

nylon fibre include automobile tyres, ropes, seat belts, parachutes and sub-
strates for coated fabrics such as artificial leather, shower and fi re hoses,

and disposable clothes for the health-care industry. In addition, engineering
plastics made of nylon exhibit high melting points; strength, toughness and
chemical inertness, and are used as bearings, zippers, gears, automobile fan
blades and pulleys (Yang, 1989).

4.2 Enzymatic hydrolysis and modifi cation of
poly(ethylene terephthalate) and polyamide:
basic principles, methods and technologies

4.2.1 Modifi cation of poly(ethylene terephthalate) fi bres
PET fibres have numerous favourable properties (see section 4.1.1) com-

pared with other textile fibres, but there are considerable disadvantages,
such as hydrophobicity, build-up of electrostatic charge, pilling tendency

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