| The existing waste of textiles have not been effectively recycled.The prime reason for the non-effective recycling of textiles is that the structure of fabric is compact and there is a wide variation of colors in the wasted fabrics.After opening and combing,the fibers are damaged and their use value is reduced.Usually the fabric waste is incinerated,buried or dumped far away,but these methods of waste disposal cause secondary pollution.The recycling of fibers can not only save a lot of textile raw materials,but also alleviate the problem of cotton grain competition;it can also reduce the environmental pollution and will promote the green trend of sustainable environmental development.The recycling of fabric waste is imminent,and an effective method is needed for recycling.Therefore,the objective of the present invention is to provide a method in which cotton fibers can be separated from a mixed textile product and to achieve cycle regeneration and multiple cycle regeneration.The cotton fiber is blended with the alkali-soluble polyester fiber,and then subjected to conventional weaving and dyeing processes.For recycling of cotton fiber,the fabric was placed in a lower concentration of alkaline solution and the polyester fibers were dissolved.The remaining loose fiber aggregates are subjected to stripping treatment and drying,and then gently combed to obtain recycled cotton fibers.Firstly,the microscopic morphology and physical properties of cotton fiber after alkali treatment were analyzed by X-ray diffraction?XRD?,Fourier transform infrared spectroscopy?FTIR?,mechanical properties were tested and bulk length test was carried out.The results showed that the cell type of alkali-dissolved cotton fiber was cellulose type I,and the crystallinity was slightly reduced.The unit cell size and the chemical composition remained the same.The breaking strength of the cotton fiber after alkali treatment was 93.29%,and the length of the main body was slightly increased.The low alkali treatment has little damage to the cotton fiber,and the obtained recycled cotton fiber can still be used as a new cotton fiber.Then,the knitted fabric dyed with reactive dyes was selected as the research object.The hydrogen peroxide was selected as the stripping agent.The stripping rate,the breaking strength retention rate and the length of the main body were characterized.The single factor experiment and the orthogonal test were combined by mathematical statistics.The decolorization process of the knitted fabric waste dyed with reactive dyes was studied,and the best stripping process was obtained at the following conditions;the hydrogen peroxide concentration was 75 ml/L,the stripping temperature was 90°C,and the treatment time was 70 min.Under the optimal conditions,the double-bath method and the one-bath method were used to study the recycled cotton fiber multiple times.The results showed that the phenolic functional groups were formed at the stripped cotton fibers.Compared with the raw cotton fiber,the obtained recycled cotton fiber treated by one bath method is more oxidized,the crystallinity loss is higher,and the grain size is also slightly smaller;the surface color depth K/S value of the recycled cotton fiber is increased when re-dyed.Mechanical properties and body length also have high damage.Finally,the indigo denim fabric dyed with vat dyes was taken as the research object,and the multi-cycle recycling process of cotton fiber in denim fabric was studied.The results showed that the cotton fiber still belonged to the cell type of cellulose I after repeated treatment with the lower concentration of sodium hydroxide solution.The grain size did not change significantly,but the crystallinity was decreased;it appeared above 3500 cm-1.The absorption peak of the combined alkali and the K/S value of the recycled cotton fiber first increased and then decreased;the mechanical properties and the length of the body had a certain degree of damage. |
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