worldwide, in large quantities crab and shrimp As such, the shells of shellfish are thrown into the environment without being evaluated.
- With today's increasing environmental laws and the re-evaluation of wastes, new products have started to be obtained from these shells.
- At the beginning of these products kit is coming.
- kitIt is the second most common biopolymer in the world after cellulose.
- Chitosan, the main derivative of chitinLike many sectors, it also has a wide range of use in textile processes.
Worldwide, large quantities of crab and shrimp shells are thrown into the environment untreated by seafood manufacturing companies. Especially in recent years, with the re-evaluation of wastes on the agenda, instead of being left to rot, shellfish are re-evaluated by chemical or biological methods and new products are obtained.
Among the products made in this way chitin and its derivative, chitosan. Chitosan, a natural biopolymerEspecially for the last 50 years, it has been an interesting material for researchers.
- kit which has many advantages over chitosan food, cosmetics, agriculture, medicine, paper and tekstil It has been used in many industries, including
A large amount of water and energy is consumed during textile finishing processes. However, dyestuffs and auxiliaries left in the waste water also have a polluting effect. Pollution and chemicals used to remove the color of wastewater cause additional pollution. All these factors pose a threat to the increasingly stringent environmental laws. For this reason, the search for new substances that can replace toxic chemicals and waste water load in the textile industry continues.
Chitosan, a biopolymer that can be obtained in abundance from natural sources,
- It is not toxic to living things,
- Chemical and physical properties
In terms of its superior properties compared to other biopolymers, it appears as a suitable material in the textile industry like many other industries.
Chitin and chitosan
Shell solid and liquid wastes that cannot be used in seafood processing factories create a great potential. Shellfish processing residues constitute 1050% of solid waste in the USA. These residues reach approximately 5x10 tons in the world. Remnants of seafood processing factories are used in sea, stream, etc. In addition to causing a very important problem such as pollution, it also poses a great risk for the environment.
From the perspective of Turkey, on average, 6383-6890 tons of waste is generated for shrimp, 2741-2840 tons for oysters, and 6328-1800 tons for mussels. However, unfortunately, shellfish processing residues cannot be adequately evaluated in Turkey.
Shellfish processing residues solid and liquid analyzed in two ways.
- Chitin and its derivatives from solid residues,
- Soup and crustacean concentrates from liquid residues
It is obtained.
Chitin and chitosan, a natural and non-toxic biopolymer, are mainly obtained from crab and shrimp shells.
Besides, insect shells are also rich in chitin source. Approximately 23,5% chitin in insect shells While this ratio is between 17% and 32% in crab and shrimp, respectively. There is 6.29% nitrogen in shrimp chitins and 6.24% in crab chitins.
- Chitosan is a polysaccharide obtained as a result of acetylation of chitin.
- Chitin is the second most common biopolymer in the world after cellulose.
- It is the main component of shellfish such as crabs and shrimps, and is also found in the skeleton of insects and in the structure of cell walls of fungi.
Although there are many derivatives of the kit, the most important it is chitosan. Chitosan was first discovered by Henri Bracannot in 1811. Bracannot tried to dissolve chitin found in mushrooms in sulfuric acid, but was unsuccessful. In 1894, Hoppe-Seyler treated chitin in potassium hydroxide at 180oC (deacetylation) and obtained “Chitosan”, a product with reduced acetyl content.
In 1934, two patents were obtained, one on the production of film and the production of fiber from chitosan. In the same year, he was very well oriented by Clark and Smith. chitosan fiber production has also been successfully carried out.
The first comprehensive publication on chitin and chitosan was made by Muzarelli in 1977. Later, various international symposiums and researches on this subject and ongoing studies have survived to the present day. Academic and industrial research to find and apply new application areas of these versatile materials is still extensive and intensive.
Generally speaking, the shell of marine animals such as crabs, lobsters and shrimps consists of 30-40% protein, 30-50% calcium carbonate and calcium phosphate and 20-30% chitin.
Protein base in shellfish allergic in humans may cause.
Therefore, complete removal of protein is particularly in biomedical applications very important for its use. For this purpose, the covalent bonds in the protein complex of chitin are broken and the process is called deproteinization. However, due to the danger of depolymerizing the biopolymer of the chemicals used, it is necessary to be careful during the process.
Usage Areas of Chitosan
- From medicine to food
- From agriculture to cosmetics,
- From pharmacy to wastewater treatment
- To the textile industry
It can be used in countless fields.
Although chitosan is widely used in various countries, this rate is lower in our country. It is also used for many purposes in the textile industry.
- It provides antimicrobial properties,
- Providing non-shrinkage in wool fabrics, -
- Reducing the amount of salt in reactive dyeing,
- Gaining dyeability of cotton with acid dyestuffs,
- It provides antistatic properties,
- It is used as a deodorant,
It can be counted. Moreover, There are also various antimicrobial fibers produced from a mixture of chitosan and other fibers..
As an example of these;
- Crabyon (mixture of chitosan and viscose, TEC SERVICE),
- chitopoly (chitosan and polynosic fiber blend (Fuji)
It can be given.
Chitosan has gained a lot of importance in medical textiles. Since the mid-1960s, studies on this subject have been carried out in many Asian countries, especially in Japan. Chitosan is widely used to provide tissue, especially in wound treatment.
Chitosan in the medical field;
- Imitation leather,
- surgical sutures,
- artificial blood vessels,
- Controlled drug release
- Contact lens making
- Cholesterol control (fat binder),
- Tumor inhibitor, antifungal, antibacterial and hemostatic effect etc.
It can be sorted as
In-vivo tests have shown that chitosan has no adverse effects on the human body. If chitosan is used as a tablet, it can be broken down by the lipase enzyme in the saliva or stomach. As a result of decomposition, non-toxic products such as amine sugars are released.
Chitosan also has a cholesterol-lowering effect. Due to its polycationic structure, it interacts with negatively charged lipids and lowers cholesterol.
USE OF KITOSAN IN TEXTILE FINISHING
The use of chitosan in the textile industry; fiber production and textile finishing processes are divided into two main categories: Chitin and chitosan also have uses as films.
Chitin and Chitosan Fibers
Chitin and chitosan fibers have been known for many years. First of all, the kit artificial silk fibers used as raw material in production. Subsequently, many studies were carried out for the production of chitosan fibers in the 1920s and 30s. However, these studies were interrupted by the discovery of nylon in the years that marked the beginning of a new era in the fiber industry.
Renewable resources have been researched since the 1970s. Meanwhile, with the re-concentration on chitin and chitosan, new properties were discovered:
Due to its properties, it has many advantages in terms of environment such as binding heavy metals. Due to all these features, research on chitin and chitosan has been increasing in recent years.
As it is known, all chemical fibers are obtained as fiber spinning from melt and spinning from solution. Chitin and chitosan contain very strong bonds due to the hydroxyl, acetamide and amino groups in their structures.
- Therefore, their melting points are also quite high. Therefore, melt spinning, one of the fiber spinning methods, is not suitable.
- On the other hand, both polymers can only dissolve in polar solvents at high boiling temperatures due to strong polar groups. This method is not suitable for dry fiber spinning as it is based on the evaporation of the solvent during fiber spinning.
- The most suitable fiber spinning method for chitosan is wet fiber spinning..
It is necessary to prepare a stable fiber spinning solution in order to spin the fiber from the kit.
Chitosan Fibers Production
Chitosan is more easily soluble than chitin. The first study on the production of chitosan fibers was made in 1980. For fiber production, 3% chitosan was dissolved in 0,5% acetic acid and sent into a 5% NaOH bath after passing through nozzles. In this way, fibers with a strength of 2.44 g/den and an elongation at break of 10.8% were obtained.
- A similar process was obtained by adding 3% Nalaurylsulfate in 1% chitosan 2% acetic acid solution.
- In addition, chitosan fibers were obtained by using dichloroacetic acid as solvent and CuCO3-NH4OH as coagulant.
- In another study, a urea-acetic acid mixture was tested as a solvent for chitosan. The coagulation bath consists of 5% NaOH. In this way, 3,2 denier, 12,2 g strength and 17,2% elongation at break fiber were obtained.
- In another R&D, chitosan fibers were obtained according to the wet fiber spinning method by using 2% acetic acid as a solvent. In the study, the effects of epichlorhydrin concentration, which is used as a crosslinker, on the mechanical, thermal and morphological properties of the fiber were investigated. From the experimental results, it was determined that the swelling properties decreased with the increase of epichlorhydrin concentration, the change in concentration did not create a significant disadvantage on the mechanical properties of the fiber, and the best epichlorhydrin concentration was 0.05 M in terms of fiber properties.
- In another R&D, chitosan was dissolved in acetic acid and coagulated in various coagulation baths (solutions containing copper sulfate + ammonia solution, ethylene glycol + NaOH and Na2SO4 or sodium acetate). The researchers obtained modified chitosan fibers by treating chitosan with tropocollagen. Tropocollagen (50%) and collagen consist of peptide chain in triple helix structure and are found in connective tissues. These fibers, which are also compatible with blood, have been made suitable for use in artificial tissues and bandages for humans and animals.
- In another R&D, a water-soluble chitosan derivative was obtained and then fiber was drawn from it and used in the production of bandages. After producing bandages from these fibers, a trial was conducted on patients for a week. As a result of the trials, it has been seen that chitosan, which has a very compatible structure to the tissues, provides faster healing compared to the bandages produced from other fibers. It has also been determined that chitosan strengthens skin regeneration.
- In another R&D, chitin and chitosan fibers were obtained by electrospinning method. As is known, in the electrospinning method, high voltage is applied to the polymer solution and electrically charged jets are formed. These jets are then dried, collected on a plate, and thus nanofibers are produced. Nanofibers have a variety of uses due to their large surface area and extremely high porosity. The fibers obtained by electrospinning by using 3-6% chitin and HFIP (1, 1, 1, 2, 2, 2-hexafluoro-2-propanol) as solvents by weight, were then subjected to acetylation with 40% NaOH, after washing. Then, it was dried under vacuum and chitosan nanofibers were obtained. Fibers with different degrees of deacetylation were also obtained by this method. For this, 2-4% acetic acid was used as a solvent, and a mixture of CuSO4-NH4OH or CuSO4-H2SO4 was used as a precipitation bath. The fiber obtained is in the form of a copper-chitosan mixture, and only chitosan fiber remains after the copper is removed in the next stages. As a general result of the studies, it was determined that the most ideal settling bath composition for chitosan fibers was a mixture of NaOH and Na2SO4.
Since chitosan is an expensive material, it is only used as a special purpose fiber.
Its main use is in medical textiles, including antimicrobial and wound healing.
Use of Chitosan in Cotton Dyeing
Since chitosan is cationic in acidic conditions, it can easily absorb anionic dyestuffs such as direct, acid and reactive dyestuffs thanks to electrostatic attraction forces. Some cotton lots cause dyeing problems in the production and dyeing of cotton fabrics. Cotton cannot absorb the dyestuff properly and light and dark colors may appear.
Small knots, called neps, in immature cotton fibers do not take up the dyestuff as well as mature cotton fibers. As a result, it is stained very lightly or appears as colorless spots. Immature cotton is caused by various reasons such as disease, insect impact, premature farming and unsuitable weather conditions.
Use of Chitosan in Wool Treatment
One of the undesirable properties of wool fibers “felting” features come. Felting occurs as a result of the intertwining of the fibers as a result of the mechanical effect in the aqueous medium. While this situation is an advantage in felt production, it is an undesirable situation especially in woolen products in the form of clothing due to their tendency to shrink.
Felting is caused by the flake layer on the wool fibers. The flakes on the upper surface of the wool fibers show different frictional resistances from root to tip and from tip to root under any mechanical action, and this causes the fibers to move in one direction.
As a result of the arrangement of the flakes on the wool fiber towards the fiber end, the fibers always tend to move towards the root direction. The difference in friction resistance in both directions creates a scale on the felting ability of the fibers, and this is called the "directed friction effect".
It is expressed as directed friction effect = End-to-root friction coefficient - Root-to-end friction coefficient.
Various non felting finishing processes are applied to make woolen products machine washable. These,
- disintegrating methods (chemical modification),
- Added methods (physical modification),
- Combined methods (Chlor-Hercosett method)
- New methods (oxidation+enzyme, plasma)
It can be grouped under four main groups.
One of the ene ski methods applied to impart shrinkage to wool fibers. Chlorine-Hercosett method. One of the biggest drawbacks of this method is that it creates an AOX load in the waste water. Due to the increasing environmental laws in recent years, various restrictions have been imposed on such substances and the search for new environmentally friendly methods has begun. As an alternative to chlorination, ecological methods such as permonosulfate, enzymatic treatments and plasma are recommended. In addition, wool fibers are also treated with various polymers to cover the flake layer. One of the polymers gaining importance in this regard is chitosan.
With the use of chitosan biopolymer instead of synthetic polymers in woolen products, many advantages over other polymers, especially chemical and biological compatibility, come to the fore.
When chitosan is applied to wool fibers, the flake layer on the fiber surface is covered with polymer and the desire of the fibers to move in different directions is restricted.
When chitosan is applied to the wool fabric, its surface is covered with chitosan and a layer is formed. During dyeing, the dyestuff that binds to the chitosan on the fiber surface via amine groups migrates towards the fiber over time, and more dyestuff is bound to the fiber by re-binding dyestuff anions to the emptied parts. As can be seen, the dyeing mechanism in chitosan-treated wool does not only occur by direct diffusion into the fiber, but there are other possibilities as well. Since the number of groups to which the dyestuff can be bonded is higher in chitosan-treated wool, it absorbs dyestuff faster than untreated wool. At the same time, the chitosan on the surface also facilitates the migration of the dyestuff to the fiber in the advanced stages of dyeing.
Use of Chitosan in Antistatic Finishing
- Synthetic fibers with hydrophobic structure such as polyamide, polyester, polyacrylnitrile do not absorb water or moisture, and static electricity occurs as a result of friction.
Static electrification; It causes many negativities such as electric shock, contamination of fibers, deterioration of electronic devices such as computers.
In the research, it was tried to use chitosan, which has a high moisture holding capacity, as an antistatic agent. For this purpose, PES fabrics were first subjected to alkaline pretreatment and then treated with a chitosan/malonic acid mixture. It has been observed that the loading of synthetic fibers can be reduced by static electricity after treatment with chitosan, a hydrophilic polymer.
Use of Chitosan in Textile Printing
The use of chitosan as a combined binder and thickener in pigment printing was investigated and compared with a commercial paste system with a molecular weight of 171,000 chitosan. Chitosan printing paste was obtained by first dissolving the chitosan in dilute acid and then adding pigment and mixing until a homogeneous dispersion was obtained. Polyester and polyester/cotton fabrics were printed with chitosan pigment printing paste and fixed at 150oC for 6 minutes after curing at room temperature.
It has been observed that fabrics printed with printing paste prepared with chitosan give very good results in terms of color fastness compared to fabrics printed with other system. The only negative of the study is that the paste prepared with chitosan gives slightly lower results in terms of color yield. It is thought that this may be due to the lower stability of the pigment dispersion in chitosan paste, and it is stated that studies will continue in this direction.
Use of Chitosan as a Sizing Agent
In this study, the usability and degradation of chitosan as a sizing agent were investigated. As mentioned before, chitosan has been used as a sizing agent because it has a good film-forming property. However, since the removal of chitosan, which is used as a sizing agent, may cause problems later, studies have also been carried out on this subject. Enzymes such as cellulase, xylinase, pectinase, papain were tested for desizing. As a second method, Van-Slyke fragmentation was tried.