Page 100 - Advances in Textile Biotechnology

Enzymatic hydrolysis and modifi cation of core polymer fi bres 81

and difficult oil stain release. The hydrophobicity of the fibres hinders water
penetration into the pores of fabric, resulting in bad comfort properties
because perspiration is not absorbed by the material. From the consumer’s
point of view improved hydrophilicity results in a number of improvements:
improved washability, improved removal of oily stains, and enhanced
comfort.

In the textile industry various finishes, such as anti-static fi nishes, and
colouring agents are applied. Owing to the crystallinity and hydrophobicity
of the PET fibres, chemicals can hardly penetrate into the fibre or physically

bind to the fibre surface. The absence of reactive groups at the PET surface

hinders chemical reactions at the surface. Various techniques are available
to increase hydrophilicity of PET. Copolymerization (Pang et al., 2006) is a
suitable technology to adjust PET properties, though effects are not limited
to the surface of the fibre, the bulk characteristics are modified as well.

Another technique to make PET more hydrophilic is an alkaline treat-
ment at high temperature. Polyester bonds are hydrolysed and, conse-
quently, hydrophilicity is increased. However, because NaOH diffuses into
the fibre, the favourable bulk properties of polyester, particularly the

strength, are also affected. The alkaline treatment also results in pitting
corrosion (Brueckner et al., 2008; Donelli et al., 2009; Kim and Song, 2006),
not to mention increased energy consumption, the necessity to neutralize
the pH of the liquid, and increased water consumption. Plasma treatments
have been developed to modify the surface of polyesters (Höcker, 2002;
Morent et al., 2007, 2008), but the technique is rather expensive and not yet
generally accepted in the textile industry. The technique is non-specifi c,
relatively difficult to control, and ageing can occur as a result of reorienta-

tion or migration.
In the past decade new environmentally benign and specifi c processes
have been developed based on modern enzyme technology. Synthetic mat-

erials, such as PET fibres, have generally been considered resistant to bio-
logical degradation. However, the application of enzymes is not limited to
biological materials. Fairly recently it was established that enzymes are also
able to act on synthetic textile materials.
Various research groups assessed the potential of laccases, lipases, poly-
esterases (serine esterase) and cutinases in the oxidation or hydrolysis of
PET textile materials with the aim of modifying and eventually functional-
izing the material (e.g. Alisch-Mark et al., 2004, 2006; Araújo et al., 2007;
Brueckner et al., 2008; Donelli et al., 2008, 2009; Feuerhack et al., 2008; Hsieh
and Cram, 1998; Kim and Song, 2006, 2008; Kontkanen et al., 2006;
Liebminger et al., 2007; Liu et al., 2008; Miettinen-Oinonen et al., 2002, 2004;
Müller et al., 2005; Nimchua et al., 2006; O’Neill and Cavaco-Paulo, 2004;
Silva and Cavaco-Paulo, 2008; Silva et al., 2005a; Vertommen et al., 2005;
Wang et al., 2008; Yoon et al., 2002).

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