Page 47 - New Cloth Market November 2022 Digital Edition

Chitosan-Based Sustainable Textile Technology: Process, Mechanism, Innovation & Safety

molecular skeleton. In addition, it phosphate and 6% resin shows presence of ethanol. The final product
functions as blowing agent and 36.557% residue, while the is washed with fresh ethanol to remove
releases nitrogen as a result of decomposition temperature is reduced extra nickel (II) nitrate hexahydrate
molecular destruction. by 25°C compared to the untreated and dried at 60°C in a vacuum dryer. It
fabric [70]. is then blended with polyvinyl alcohol
Therefore, a potential nitrogen- (PVA) that provides film or fibers or
phosphorous bonding could be Furthermore, apart from a reaction nanofibers [75] to synthesize flame-
established as flame retardant mixture, layer-by-layer (LBL) deposition and chemical-resistant materials. The
materials. Chitosan-based flame processes are also examined for heat release rate of nickel chitosan
retardant materials have been designed developing a nanolayer formation [68] phosphate (NiPCS) blended PVA
by chitosan-phytic acid [68], chitosan- on substrate or fabric. In this process, decreases substantially compared to
sodium polyphosphate [69], chitosan the solution of chitosan is prepared the raw PVA. The microscale
phosphate (chitosan-orthophosphoric using HCl and phytic acid salt (2 wt.%) combustion calorimeter test has
acid) [70], chitosan phosphate-nickel in deionized water. exhibited the peak of heat release for
[71], chitosan melamine phosphate PVA at 155 W/g, while NiPCS blended
(chitosan-melaminesodium The branched polyethyleneimine (1 PVA having a peak at 40 W/g [71].
hexametaphosphate) [72], chitosan- wt.%) is used to increase the adhesion
diammonium hydrogen phosphate [73], of cotton fabric as a primary layer. The Besides, the total heat release rate is
etc. It is expected that the presence fabric is dried and dipped sequentially decreased by NiPCS from 18.2 to 10.4
of ammonium nitrogen in chitosan in positively and negatively charged kJ/g, which underlines the main action
would provide the synergistic effect solutions. The process continues up to of NiPCS. Moreover, the increased
with phosphate groups against flame desired level of the bilayer to achieve amount of NiPCS enhances the char
or fire [74]. The preparation of chitosan effective layers for flame retardancy. formation that resists the transfer of
phosphate has been conducted using After the dipping process, it is wrung oxygen and heat. This process leads
many processes. For example, 23 g to release excess solution and dried to delay the thermal decomposition of
chitosan has been added to a solution at 70°C for 2 h. The thinnest coating materials due to the improvement in
that contains urea (40 g), phosphoric which is approximately 10 nm thick has thermal stability at high temperature.
acid (40 ml), and dimethylformamide been achieved at pH 4. The thickness
(350 ml) at 100°C for 5 h. At the end of contains 30 bilayers on the cotton Chitosan: a hydrophobic material for
the process, the product is filtered and fabric surface where one bilayer water repellent textile
washed with isopropyl alcohol (50%) consists of one positive and negatively
and dried at 60°C. In this process, a charged layers. More than 90% Superhydrophobicity is observed in
commercial resin, knittex FLC, has residues were left, while the flame duck feather, wings of butterflies, the
been provided by Ciba-Geigy propagation is completely stopped legs of water striders, etc. The specific
(Switzerland). The resin allows the during the vertical burn test. In addition energy of surface is a quantitative
capturing of phosphate by crosslinking to chitosan phosphate, Shuang and his value to comprehend the understanding
and by forming a network to fix the coworkers have focused on the metal of how water droplets interact with a
chitosan with cellulose. In addition, the ion binding ability of chitosan surface. It is highly relevant to the
increased amount of resin phosphate that results in a synergistic contact angle and roughness factors
concentration (2–8%) leads to a effect and enhanced flame retardant [76]. Nanoscale chitosan coating may
reduction in tensile strength (140-114 property by adding nickel ions [71]. The be applied on the surface of cotton and
kg) and elongation at break (21–15%). process involves 2 g chitosan and 30 polyester fibers to achieve rough
In contrast, the tensile strength and ml methanesulfonic acid in magnetic surface. These rough surfaces are
elongation at break increase for using stirrer putting on an ice bath in inert further treated with silicon [77] and
a higher concentration of chitosan atmosphere to avoid moisture, by fluoride [78] to reduce the surface
phosphate. It also guides to increase adding phosphorus pentoxide (10 g). energy. The fabrics are dipped for 1 min
the amount of phosphate (0.095– in a chitosan solution in 1% acetic acid
0.314%) content in the coated fabric The chitosan phosphate is achieved before being squeezed. The wet fabric
and shows higher residue contents by from the reaction and washed with is neutralized by ammonia gas for 1
releasing very less volatile components acetone, methanol, and ether. The min and dried 80°C for 5 min [79]. The
compared to untreated fabric. A drying process is realized at 60°C dipping-padding process with chitosan
compensation effect works between using vacuum. Nickel (II) nitrate allows forming a thin film on the fabric
the concentration of chitosan hexahydrate and the dried chitosan surface. Later on, ammonia treatment
phosphate and resin. The cotton phosphate react in the ratio of 10:1 with changes the pH of the wet fabric, and
surface treated with 8% chitosan each other at 60°C for 1 h in the insoluble-nanoscaled chitosan is

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