| Due to excellent water-and oil-repellent properties of fluoroalkly compounds, the copolymers of derivatives of PFOS(Perfluorooctane sulfonates) and PFOA(Perfluorooctanoic Acid) are widely used in water-repellent, oil-repellent and anti-fouling fields over the past few decades.Yet the study was found that PFOS and PFOA existed serious threat to ecological environment and biological health. Therefore, some international organizations including the ZDHC(Zero Discharge Of Hazardous Chemicals), required the banning use of long chain fluorinated compounds since January 1, 2015. This provide the new opportunities and challenges to new agent and finishing technology involving water-repellent field.In order to having excllent water-repellent property, this study is to build rough surface on cotton fiber, and then finish the rough surface with low surface energy material. Firstly, prepared nano microcrystalline cellulose(NCC) by acid hydrolysis, using it to create a rough structure. The preparation conditions of NCC were optimized. Influence of preparation conditions to particle size of NCC were discussed, according to Potential and nano-particle size analyzer and SEM. Structure and property of NCC were charactered by FT-IR, X-ray diffraction and thermogravimetry. The results indicate that optimized preparation conditions of NCC are: H2SO4 concentration is 60wt% to 65wt%, temperature is 40-50 ℃, and acid hydrolysis time is 2 to 3 h. And the prepared NCC have the same molecular structure and crystal structure with microcrystalline cellulose(MCC). Compare with MCC, NCC have higher crystallinity, lower thermal stability and thermal cracking rate.To added Methacrylic Acid Stearyl Ester, allyl glycidyl ether and polyhydrosiloxanes into the reaction system, synthesized water-repellent f inishing agentwith low surface energy by hydrosilylation reaction. The synthetic conditions of modified s ilicone was optimized. Influence of concentration of water repellent agent, curing temperature and washability of treated fabric to water repellency were evaluated by spray test and static contact angle test. The results show that the optimized condition of the synthesis of modified silicone are: the hydrogen content of hydrosilicone oil is 0.2%, the ratio of carbon-carbon double bond/silicon hydrogen bond and the eighteen methacrylate/allyl glycidyl ether is1.2:1and 9:1, respectively. FT- IR test show that the expected structure of modified organic silicon are formed. And the modified organic silicon have the excellent solubility in ethyl acetate solution.The water repellency grade and static contact angle of the treated fabric reach 85 marks and 144.0 f the treatedly, when 10 g/L modif ied silicone is used followed by curing at 160 ℃. The water-repellency of treat fabric remain the same after 1time of washing. But after 10 times of washing, the water repellency grade and static contact angle of the treated fabric reach 60 marks and 109.3°, the water-repellency sharply decreasing.Influence of finishing technological process, parameters of finishing and particle size of NCC of synergistic finishing of NCC and organic silicon water repellent agent on water repellency were discussed, according to potential and nano-particle size analyzer and SEM. Influence of NCC on water-repellency of different concentration of silicone water-repellent agent was analyzed. Influence of washability of treated fabric to water repellency was evaluated. The result indicate that the NCC cooperated with modified silicone for water repellent finishing should use two-bath process. The relevant parameters of finishing are: drying time of NCC and water-repellent agent are 180 s and 90 s, respectively, curing time is 90 s, curing temperature is 160 ℃. SEM show that the treated fabirc have a rough surfce after the finishing of NCC. This sharply increase the water repellency of the treated fabirc, especially the NCC with particle size between 200 nm-300 nm. When the concentration of organic silicon water repellent agent is low, synergistic effect of NCC can increase the water repellency of treated fabric obviously. With the increase of concentration of organic silicon, influence of synergistic effect of NCC on water-repellency is weakening. After 5 times of washing, the water repellency grade of treated fabric by the synergic finishing of NCC and silicone water-repellent agent show a a greater drop. |
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