23
2018). This improves the wetting characteristics of substrates and is also beneficial
for subsequent coating operations, such as with fluoropolymers and titanium and
zinc oxide particles.
Hydrolytic treatments have also been carried out with enzymes, and there is a
long history of such cellulose treatments, and now it has been expanded to include
other fibers such as wool, where it is used as an anti-felting treatment (Kaur and
Chakraborty 2015). The modification of the enzymatic surface of the dyed material
has been used to remove part of the color and increase the abrasive effects during
the garment wash down processes. As an example, cellulases have been used to
degrade the surface of cellulosic fibers surface and intensify the color release in the
denim wash down, which replaces substantial amounts of oxidants, e.g. hypochlorite or potassium permanganate, and therefore reduces pollution (Schimper et al.
2011). In recent research works, enzymatic hydrolysis of polyesters has been carried out with cutinases, esterases and lipases, as a means to generate hydroxyl and
carboxyl groups on the surface and increase the roughness (Kim and Song 2010;
Lee and Song 2010; Vecchiato et al. 2017). A similar approach has been used with
polyamides by using acylases, amidases, peptidases and proteases (Song and Kim
2013; Kim and Seo 2013; Abo El-Ola et al. 2014; Periyasamy et al. 2017; Kanelli
et al. 2017).
3.2.2 Crosslinking
Unlike grafting treatments, crosslinking treatments are generally performed to
change the bulk properties, e.g. to improve the mechanical properties of the fibers
(resilience), impart morphological and chemical stability, as well fix functionalization agents. In the latter case, the treatment processes can be tailored to limit the
effects on the fiber surfaces.
3.2.2.1 Treatments to Improve Mechanical Resilience
Cellulosic fibers easily absorb moisture/water and swell, which leads to a breakdown of non-covalent interactions between polymer chains. This causes the chains
to move from their original configurations under external stress. Upon removal of
moisture/water, the non-covalent interactions are restored. The displaced polymer
chains do not return to their original configurations, and these changes are reflected
as creases in cellulosic apparel (Schindler and Hauser 2004). Crosslinking treatments are used as a means to improve crease strength, since the treatment retards the
swelling of the fiber in moisture/water and, therefore, the chain displacement is also
retarded. A large proportion of crosslinking treatments on cellulosic fibers to impart
crease strength are performed using N-methylol reagents derived from melamine or
urea reactions with formaldehyde (e.g. N,N’-dimethylol urea (DMU), N,N’dimethylol-4,5-dihydroxyethylene urea (DMDHEU) and trimethylol melamine
3 Reactive Modification of Fiber Polymer Materials for Textile Applications
2018). This improves the wetting characteristics of substrates and is also beneficial
for subsequent coating operations, such as with fluoropolymers and titanium and
zinc oxide particles.
Hydrolytic treatments have also been carried out with enzymes, and there is a
long history of such cellulose treatments, and now it has been expanded to include
other fibers such as wool, where it is used as an anti-felting treatment (Kaur and
Chakraborty 2015). The modification of the enzymatic surface of the dyed material
has been used to remove part of the color and increase the abrasive effects during
the garment wash down processes. As an example, cellulases have been used to
degrade the surface of cellulosic fibers surface and intensify the color release in the
denim wash down, which replaces substantial amounts of oxidants, e.g. hypochlorite or potassium permanganate, and therefore reduces pollution (Schimper et al.
2011). In recent research works, enzymatic hydrolysis of polyesters has been carried out with cutinases, esterases and lipases, as a means to generate hydroxyl and
carboxyl groups on the surface and increase the roughness (Kim and Song 2010;
Lee and Song 2010; Vecchiato et al. 2017). A similar approach has been used with
polyamides by using acylases, amidases, peptidases and proteases (Song and Kim
2013; Kim and Seo 2013; Abo El-Ola et al. 2014; Periyasamy et al. 2017; Kanelli
et al. 2017).
3.2.2 Crosslinking
Unlike grafting treatments, crosslinking treatments are generally performed to
change the bulk properties, e.g. to improve the mechanical properties of the fibers
(resilience), impart morphological and chemical stability, as well fix functionalization agents. In the latter case, the treatment processes can be tailored to limit the
effects on the fiber surfaces.
3.2.2.1 Treatments to Improve Mechanical Resilience
Cellulosic fibers easily absorb moisture/water and swell, which leads to a breakdown of non-covalent interactions between polymer chains. This causes the chains
to move from their original configurations under external stress. Upon removal of
moisture/water, the non-covalent interactions are restored. The displaced polymer
chains do not return to their original configurations, and these changes are reflected
as creases in cellulosic apparel (Schindler and Hauser 2004). Crosslinking treatments are used as a means to improve crease strength, since the treatment retards the
swelling of the fiber in moisture/water and, therefore, the chain displacement is also
retarded. A large proportion of crosslinking treatments on cellulosic fibers to impart
crease strength are performed using N-methylol reagents derived from melamine or
urea reactions with formaldehyde (e.g. N,N’-dimethylol urea (DMU), N,N’dimethylol-4,5-dihydroxyethylene urea (DMDHEU) and trimethylol melamine
3 Reactive Modification of Fiber Polymer Materials for Textile Applications