Preparation Of Pupa Chitin/Chitosan And Antibacterial Finishing To Cotton Fabrics

Chitosan is the deacetylated product of chitin and its application areas are expanding because of its excellent properties. Thus the demand for chitosan is continuously increasing. China's silk reeling industry produces about 100,000 tons pupa every year. When isolating protein from the silkworm, it generates a large number of residues which contains as high as 36% chitin more than that of shrimp and crab. And silkworm pupa chitin/chitosan also has some better performance than that of shrimp and crab, so it is a superior chitin/chitosan resources. At present, the preparation of silkworm pupa chitin/chitosan hasn't realized scale production, the mainly tissue is that products quality is unstable and varies widely in different production processes. Therefore, the dissertation test takes residue in the pre-treatment of pupa protein extraction as raw material, make the silkworm pupa chitin/chitosan preparation route be further optimized and process be fixed, meantime, discuss the detail performance of products, in particular effects which is like solubility, antimicrobial, molecular structure of chitin on bleaching. Silkworm pupa chitosan on the antibacterial applications for cotton fabric is also studied. The main results are reported as follows:(1) First, protein removal with NaOH, and then desalination with the lower price of HCl. This effect of alkali on the chitin macromolecule is much smaller than acid and the proteins removal time is short in alkaline solution, it reduces the impact of acid on the molecular chain comparing traditional preparation methods of silkworm pupa chitin.(2) When studying the bleaching effect of chitin, the test uses analysis method of single-factor, in which such as H₂O₂ concentration, pH, treatment temperature, time and liquor ratio is investigated, and then using of the correctitude design which containe 4 factors optimized bleaching process, the best conditions is:H₂O₂ concentration 20%, pH value 11, temperature 80℃, the processing time 2h, bath ratio 1:40. Experimental product of chitin is white flake or powdered solid, ash content is 0.59%, nitrogen content is 5.80%, extraction rate is 39.82%, bleaching degree is 45.20%. This chitin quality of silkworm pupa is relatively stable.(3) Select the different whiteness of chitin samples in order to further study the relationship between the different bleaching effect and product performance:solubility becomes better and viscosity becomes smaller with the bleaching effect improvement.Silkworm pupa chitin has a good antimicrobial activity, the greater its whiteness is, the better its antibacterial activity is. Silkworm pupa chitosan has good antimicrobial activity, the greater its whiteness is, the better its antibacterial activity is. IR spectra of chitin molecular structure before and after bleaching are observed and found the basic skeleton of chitin do not change, bleaching is better, the molecular chains became shorter, hydrogen bonds are destroyed by the interactions and the crystallinity decreased, which is key reasons that silkworm pupa chitin reaction performance increases, the result provides a theoretical basis in order to further solve the difficult problem of chitin solution, contribute to the depth study of chitin in other development and application of performance.(4)Preparation technology of chitosan is:NaOH concentrations 40%, temperature 90℃, change alkali solution every 4 hours for three times, and treatment time 12h. It was shown that chotisan is white powder or flake, ash content is 0.53%, viscosity is 38.7mpa.s, molecular weight is 4.2×104, deacetylation degree is 94.9%.(5) On the basic of confirming silkworm pupa chitin/chitosan have good antimicrobial activity, complete finishing process of silkworm pupa chitin/chitosan for cotton fabric by the two times of Baptist-rolling technology. The result is showed that Solid-liquid ratio of silkworm pupa chitin on the cotton fabric is 58%-65% treatment effect is not satisfactory and the antimicrobial activity is lower after finishing; Otherwise, Solid-liquid ratio of silkworm pupa chitosan on the cotton fabric is 80%-85%, antimicrobial is better. Therefore, the test uses chitosan as an antimicrobial agent in the finishing of cotton fabrics. With the increasing of chitosan concentration, the antimicrobial effect gradually are changed better. When the chitosan concentration is 2.0%, antimicrobial rate of the Staphylococcus aureus is 100%, antimicrobial rate of Escherichia coli is 99.01%. After the pupa chitosan finishes cotton fabric, antimicrobial rate increases gradually to Staphylococcus aureus and Escherichia coli with the reducing of washing time, after washing by 40 times, the antimicrobial rate can reach 87.15%. The bacteria is almost no growth 24h later, indicating that antimicrobial effect of chitosan sustained,24h can be fully bactericidal and inhibit bacterial growth.(6)The test studies the wear performance changes of cotton fabric through comparing different washing time after antibacterial finishing. Finished cotton fabric startes to decrease with washing time permeability increase, the washing time continues to increase, the fabric breathability is improved; The finished fabric samples markes improvement in crease recovery, and strengthens the daily wear performance of fabric; The stiffness of finished sample is increased, fabric strength and whiteness is decreased. The result provides at feasibility heoretical basic for further research and development of antibacterial textiles using silkworm pupa chitosan.