| Mosquito nuisance is not only a big trouble in summer, but also is a risk spreading the disease. Using chemical can make some potential safety hazard, so using natural mosquito repellent from anti-mosquito plants become a good choice for modern people pursuing green and healthy. The development of fabrics with natural repellent is important for efficient utilization of natural repellent. In this paper, anti-mosquito plants, Citronella Extracts finished to Nylon knitted fabrics through microcapsule technology. Then they were given long lasting repellent effect.In this paper,the extract methods of citronella and the identification of their components, the preparation of the microcapsules, properties of citronella microcapsules and the functional finish process were discussed. And the anti-mosquito effect and the properties of the fabrics after finishing were tested.The first part of this paper included the extracting methods and process of citronella extract and analysis of effective components. Experimental results show that Soxhlet’s extraction was confirmed as optimized extracting method, and the extraction yield was 7.73 %.The extract was determined by gas chromatography—mass spectrometry and 18 components were confirmed. Most of them were Single terpenoids and oxygen-containing derivatives, which can repellent insects. citronellal and citronellol, two of them have remarkable mosquito repellent. Herbac, borneol and Alpha-Terpineol all have anti-mosquito ability. So citronella extracts can be used as natural mosquito repellent.In the second part, microcapsules containing citronella extracts as core material were prepared by complex coacervation, which used gelatin and arabic gum as cell material. By single-factor and orthogonal test, the optimal process parameters were determined as follow: the temperature of emulsification 45 ℃,the emulsification rate 8000 r/min, emulsication time 15 min, compound emulsifier’s HLB 8 and its content 0.8 %, complex coacervation PH value 4 and its stirring speed 1000 r/min, complex coacervation time 25 min, the alkalization processing 25 min under PH value 10 and temperature of below 10 centigrade, the curing temperture 30 centigrade with glutaraldehyde of 500 μl/L,the curing time 60 min.In the third part, by SEM test,the average particle size of citronella extracts microcapsules was 10.9μm. The microcapsules’ surface was continuous and the cell-wall was semi-permeable, which can release corn material. Through thermogravimetric analysis and comparison of the citronella and citronella microcapsules, citronella microcapsule thermal stability is better than that of citronella extracts itself. Through studying citronella microcapsules in 33 centigrade and 150 centigrade release law, the early release faster than late release, and release regular release function model are more in line with the first order kinetics.In the last part, the mosquito repellent finishing was used to treat polyamide fiber knitted fabric by dipping and finishing effect was tested by testing grafting rate of weight gain. Choose dip finishing effect best process through process analysis single factor: microcapsule dosage of 40 g/L, dipping temperature of 45 centigrade, dipping 90 min, graft weight gain rate can have 13.85 %. Testing the fabric tensile wear-resisting performance, it can found that tensile performance declined, and the wear-resisting performance was improved. By using the design of the anti-mosquito test box, test mosquito repellent of polyamide fiber knitted fabric with citronella microcapsule,the initial repellent effect is obvious, more than 80% repelling rate keeping 19 days, after 33 d repelling rate remained above 50%. |
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