Page 104 - Advances in Textile Biotechnology

Enzymatic hydrolysis and modifi cation of core polymer fi bres 85

measurements, Alisch-Mark et al. (2006) and Kim et al. (2008) measured
the liquid uptake of fabric (rising height), whereas Brueckner et al. (2008)
and Liu et al. (2008) used the drop method. Results from the liquid uptake
test and the drop method are affected by porosity of the fabric. Alisch
et al. (2004), O’Neil and Cavaco-Paulo (2004) and Brueckner et al. (2008)
used a dyeing assay to determine the increase of hydroxilic groups.

4.2.2 Modifi cation of polyamide fi bres

There is no doubt that polyamide polymers have unique properties, such as
high uniformity, mechanical strength, and resistance against chemicals or
abrasion. However, textile materials made of polyamide 6.6 are uncomfort-
able to wear because perspiration cannot penetrate the material and thus
evaporate. This poor water permeability is directly related to the lower
hydrophilicity of synthetic polymers, leading to static cling and stain reten-
tion during laundering process (Guebitz and Cavaco-Paulo, 2007). The

reduced wettability and hydrophilicity also make these fibres unsuitable for

specifi c finishing treatments such as coupling of flame retardants or covalent

immobilization of proteins (Jia et al., 2006). Classical methodologies to
improve hydrophilicity of the fibre, such as alkaline or acid hydrolysis, lead

to the deterioration of polyamide fibres properties such as irreversible yel-
lowing, resistance and weight loss (Cribbs and Ogale, 2003; Guebitz and
Cavaco-Paulo, 2003; Miller and Wilmington, 1955; Shukla et al., 1997; Silva,
2002). These methodologies also require high amounts of energy and chem-
icals (binders, coupling agents, etc.), which are partially discharged to the
environment. Furthermore, some of the substances used, owing to weak
bonding with the fi bre, are released from the end-products, causing serious
health risks and reducing the technical lifetime of the products.
Chemical finishers, based on hydrophilic carboxyl-containing polymers,

are widely used to increase hydrophilicity of synthetic polymers, and their

efficiency has continuously been improved, as evidenced by numerous
patents fi led (Soane et al., 2006).
During the last two decades, functionalization of polymer surfaces has
been recognized as a valuable tool to improve their adhesion properties.
Functional groups like hydroxyl, amine and carboxylic acid groups have
been introduced at polymers surface to adjust the surface free energy. Fur-
thermore, these groups have been used to increase hydrogen binding and
to facilitate chemical bonds between substrates and adhesives. Several
studies have been carried out on the introduction of specific reactive groups

at the surface of polyamide supports in order to reach higher levels of
functionalization (Blencowe et al., 2006; Buchenska, 1996; de Gooijer et al.,
2004; Herrera-Alonso et al., 2006; Jia et al., 2006; Makhlouf et al., 2007;
Marcinčin, 2002; Saïhi et al., 2005; Tobiesen and Michielsen, 2002). Recently,

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