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Preparation of Chitosan Modified Polyurethane and Wool Keratin and Their Appliaction on Antifelting Finishing of the Wool Fabrics

Author: ShiJiHua
Tutor: YanKeLu
School: Donghua University
Course: Textile Chemistry and Dyeing and Finishing Engineering
Keywords: chitosan wool keratin anti-felting finishing polyurethane strengthen
CLC: TS195.56
Type: PhD thesis
Year: 2014
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Abstract

Wool is a kind of natural protein fiber with scale layer structure, whichhas good hydroscopicity, warmth-retention and elastic properties. However, the characteristic scale layer with directional friction effects can easily generatefelting and would affect their performance greatly. Chlorideand its derivatives were used for wool anti-felting finishing in traditional process.However, AOX (absorbable organic halogen) was produced during this process and polluted the environment seriously. Waterborne polyurethane, a kind of free chlorine anti-felting finishing agent, could cover the scales of wool fiber due to the formation of a thin film. The huge amount of waterborne polyurethane is applied to get better anti-felting, which results in the hardening of fabric and bad handle feeling.Using biomass material chitosan to enhance waterborne polyurethane will reduce the usage of wool felting agent, which leads to the formation of a thinner film. As a result, this could not only improve the handle feeling, save the cost, but also improve the biodegradability of finished wool fabric. In addition, huge amount of wool generated in China are disposed as waste. Wool keratinextracting from waste wool was used as agent for anti-felting application. The valuable protein from the wasted wool could be more reasonable and effective use by this way.Therefore, the subjectstudied on preparation of polyurethane which was modified by chitosan and anti-felting finishing processes of wool fabric treated by modified polyurethane, as well as the anti-felting finishing processes of wool fabric treated by keratin extracted from the waste wool. At the same time, the related properties of the chitosan/polyurethane composite films and chitosan/keratin composite films were studied. This provides theoretical support for the industrialization of new technology in the future.In the first part, the anti-felting finishing technology of wool fabric with polyrehane modified by chitosan was studied. There is nearly no report about the effect of the size of molecular wight of chitosan on enhancement of polyurethane. So an appropriate molecular weight within a certain scope of chitosan was seleted and prepared. And the chitosan could be mixed with polyurethane in any proportion in practice. And the mixture could be prepared immediatelywhen needed. This would lay the foundation for industrialized application.Firstly, the chitosan with high molecular weight was hydrolyzed with H2O2under mocrowave irradiation in anticipation of obtaining11kinds of chitosan with different molecular weights. The effects of concentrations of H2O2and irradiation time were investigated by the single factor test. The structure of the product was confirmed by FTIR spectrum analysis. The changes in the molecular weights of the hydrolyzed chitosan are strongly dependent on the reaction time and the concentration of H2O2.Secondly, eleven kinds of the hydrolyzed chitosan were mixed with polyurethanein in certain proportion. Then they were used for antifelting finishing of wool fabrics. The effects of the chitosan molecular weights, dosage of polyurethane, and the quality percentage of chitosan on the stability, uniformity and anti-felting of the mixed solutions were mainly researched. The optimum process of antifelting finishing was determined by the results of shrinkage area and mechanical properties tests. The results showed that the area shrinkage was0.3%,which meets the requirements of factory production of common standards when the proportion of chitosan with molecular wight of3X104D was4%in proportion of polyurethane and the concentration of polyurethane was60g/L.A small amount of low molecular weight of modified chitosan was blended with polyurethane to improvethe uniformity and stability of the compound solution greatly. The solution could be prepared when needed. This could be suitable for industrial application. The amount of modified polyurethane was reduced by45%. Meanwhile, the handle feeling of the processed fabric was improved and the strenght of the fabric was enhanced.The second part was about the systematic research of chitosan/pu composite membrane performance. The polyurethane modified by hydrolyzed chitosan with viscosity molecular wight3×104D forms membrane easily.The results of DMA tests showed that the tensile strength of the modified polyurethaneincreases by40%. The chitosan effectively enhanced the polyurethane. In addition, the chitosan mainly interacted with the soft segment of the polyurethane, and undermined the interaction between the soft segment and the hard segment of the polyurethane. This could induce the increase of the micro phase separation degree and the glass transition temperature (-52℃to-45℃). Thermodynamic test results showed that the modified polyurethane has better thermal stability. FTIR test results showed that the chemical crosslinking existed between the chitosan and polyurethane.The biodegradability test results found that the addition of chitosan could effectively improve the biodegradability of polyurethane and could make its strength to decrease respectively65.7%and70.7%under the conditions of water degradation and enzyme degradation conditions. The modified polyurethane membrane surfaces appeared grooves and cracks.The third part was about wool keratin processes for wool fabric shrinkproof.Firstly, the technique of enzyme extracted wool keratin was systematically studied. Theprocessing temperature, processing time, processing bath pH value and enzyme dosage were investigated by the single factor test.And then the optimum process was selected. The analysis and comparision of the structure and properties of keratins extracted respectively by protease, molten urea and oxidation-reduction method through SDS-PAGE、ATR-FTIR, WAXD, TG and DTG tests. The dissolution mechanisms of the wool were also explored. The tests results showed that the dissolution rate and production rate of keratin protein extracted by enzymatic method were90.1%and90.1%respectively. The disulfide bonds of keratin molecular structure fracture partially ruptured and the molecular weight of the keratin was less than2kD. The keratin was in the form of apolypeptide and the crystallinity was45.22%. Its thermal stability is inferior to those extracted by the molten urea method and oxidation-reduction method.Secondly, the wool keratin solutions were applied on woolen fabric directly.The processes of different wool keratin applied on antifelting finishing of wool fabrics were discussed. Keratin with large molecular has better anti-felting effect. The effects of different processes of pure keratin, pure reductant, rough keratin, keratin/reductant, pretreatment-keratin/reductant on antifelting effect and mechanical properties were compared. Results showed that Better antifelting effect was obtained when the keratin and the reductant acted synergistically. Additional reductant and hydration pretreatment could promote the anti-felting effect. The reductant could retain the-SH of the keratin and reduct the disulfide bond in wool fabric to produce more-SH. The-SH of the keratin and wool fabric restructured to generate new disulfide bond to strengthen the combination of the keratin and wool and enhance their resistance of washing. The hydrophilization pretreatment could increase the hydrophilicity of wool and make the keratin easier to contact with the wool fabrics.The shinkage area of the processed wool fabric under the optimum condition was decreased from11.1%to1.2%. This reached the IWS standard. And the strength loss of the processed fabric was small and the handle feeling of the fabric was soft. There was no yellowing phenomenon.The fourth part was about the preparation and characterization of the keratin-chitosan composite membranes. Keratin has good hydrophilicity. Keratin film was brittle, whichaffects its application performance and is the reason for its bad antifelting effect of the wool fabric. And the chitosan and keratin reacted in the presence of the EDC to form the composite biofilm which had certain mechanical strength.The characterization and analysis of the keratin-chitosan composite biofilms were tested by Fourier transform infrared spectroscopy, X-ray diffraction spectrum, thermogravimetric analysisand so on. The results of above tests showed that chitosan and keratincrosslinked in the presence of EDC. When chitosan and keratin quality ratio was7:3, the bio-composite film has the best thermal stability and the most regular molecular arrangement.The contact angle tests found that the hydrophilicity of biological composite membranes gradually decreased with the increase of the content of chitosan. Strength test results showed that the breaking stress generally increase with the increase of the content of the chitosan. When chitosan and keratin quality ratio was7:3, the strength was the best.

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CLC: > Industrial Technology > Light industry,handicrafts > Textile industry,dyeing and finishing industry > Dyeing and finishing industry > Finishing > Chemical finishing > The wool proofing shrinkproof finishing
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