2. New technologies for textile functionalization
2.8. Biotechnological treatments
Biotechnological treatments
- in the
textile industry - enzymes are well known and used as biological agents - by enzymatic biopolishing
Enzymes in textile bioprocessing:
Cellulase
- removal of
protruding and tangled fibers from the surface -
result:
cleaning, softness and shine of the material. Procedure
is
especially important for lyocell fibers - due to the occurrence of
fibrillation!
Transglutaminase - in wool for shrinkage resistance,
increased strength,
feel, softness, wettability, dyeing, reduction of release tendency and
protection against damage due to the use of commercial detergents.
Lipases and
esterases
- for polyester fibers for increasing hydrophilicity and absorption properties; lipase are usufull in denim bleaching as lacase-based
bleaching.
Advantages of
enzymes: processing at a lower temperature, without use of harmful
chemicals. Disadvantages of enzymes: poor stability, poor compatibility with other chemical agents, longer processing time, relatively high cost.
Today, using of biomolecules is promising for treatment of synthetic fibers.
Group of researchers are used Polylysine (PLL ) biomolecule - as a surface coating agent for simultaneously imparting hydrophilic and antibacterial functions to PA fiber.
It well known that polyamide (PA) fiber possess lower hydrophilic properties and poor wearing comfort and without antibacterial function, but in the same time PA fiber is after polyester (PES) fiber, on the second place of applied fiber for production underwear, outerwear, sports/leisure wear and decorative fabrics.
Polylysine biomolecules are used to fabricate PA as material with the hydrophilic and antibacterial surface by a dip coating technique.
Chemical mechanism: The Schiff base reaction between the aldehyde groups of glutaraldehyde (used as crosslinker) and the amino groups of PLL and PA fiber was utilized to increase washing resistance.
Results: Final effects on the hydrophilicity of PA fabric were studied by the wetting time of water droplet, while the coating effect was further confirmed by water contact angle, moisture adsorption and capillary effect tests. The functional surface of the PLL coated fabric was proved by scanning electron microscope, X-ray photoelectron spectroscopy, and charge effect.
Conclusions: The PLL coated fabric exhibited excellent hydrophilic and antibacterial properties with good washing durability. This research suggests that PLL biomolecule can be used as a surface coating agent for imparting hydrophilic and antibacterial functions to PA fiber in the same time.
Fig. 2.8.1. The effects of the dip coating conditions of PLL on the PA fabric.
The
PLL coated fabric exhibited
excellent hydrophilic
and antibacterial properties with good washing durability.
Source: W. Zhank et al.: Progres in Organic Coatings, 142, 2020, 105571, https://doi.org/10.1016/j.porgcoat.2020.105571
Surface of PLA sutures - high hydrophobicity - poor biocompatibility and cellular affinity.
Treatment: PLA sutures were etched by lipase firstly, and then grafted with chitosan - In order to increase the hydrophilicity (number of hydroxyl (-OH) bonds increase),
- the optimal conditions of treating PLA sutures by lipase were as follows: 45 Celzius degree reaction of temperature, 4.5 g/L concentration of lipase and 8 h reaction time.
- the optimal conditions of grafting chitosan onto PLA sutures were as follows: 4 h reaction time and 3 g/L concentration of chitosan. The chitosan grafted and loaded on the surface of PLA sutures, and in some areas of the sutures which led to a rough surface and large friction coefficient.
Fig. 2.8.2. FTIR: (a) original PLA suture; (b) PLA suture treated by lipase. Fig. 2.8.3. FTIR: (a) PLA treated by lipase; (b) chitosan, (c) PLA grafted with chitosan.
Fig. 2.8.4. SEM images of polylactic acid (PLA) sutures: (a) original PLA sutures; (b) PLA sutures grafted with chitosan (x500); (c) PLA sutures grafted with chitosan (x2000); (d) PLA sutures grafted with chitosan (x5000).
Source: Textile Research Journal 2019, Vol. 89(16) 3291–3302, sagepub.com/journals-permissions DOI: 10.1177/0040517518811936
Enzymatic Bleaching
The use of laccase has increased in the denim industry, particularly in the bleaching process. A sustainable replacement for traditional NaOCl bleaching is lacase-based bleaching. However, the laccase cannot be used on denim clothing that contains Lycra. The laccase is typically a “redo” type of enzyme with molecular oxygen serving as an electron acceptor. Under an aqueous environment, lacasse oxidizes and attacks the mediator, which produces free radicals (1-3). As a result, the free radicals continue to destroy indigo to produce isatin and anthranillic acid.
Table 1. Various research on enzymatic bleaching
- Choudhury, A. K. R. Environmental Impacts of Denim Washing, Muthu, Subramanian Senthilkannan-Sustainability in Denim. In The Textile Institute Book Series; Woodhead Publishing, 2017; pp 49– 81. DOI: 10.1016/B978-0-08-102043-2.00003-4.
- Liu, X.; Kokare, C. Microbial Enzymes of Use in Industry. In Biotechnology of Microbial Enzymes; Brahmachari, G., Ed.; Academic Press, 2017; pp 267– 298. DOI: 10.1016/B978-0-12-803725-6.00011-X.
- Madhu, A.; Chakraborty, J. N. Developments in Application of Enzymes for Textile Processing. J. Clean Prod 2017, 145, 114– 133, DOI: 10.1016/j.jclepro.2017.01.013.