| Nettle is a kind of wild plant with strong growth adaptability.Nettle fiber has the same characteristics as ramie fiber,such as good hygroscopicity and high strength,which can provide spinning raw materials for the textile field.Nettle fiber has high strength,low elongation,large rigidity,poor elasticity,poor flexibility,which it shows poor cohesion and poor fiber formation between fiber-to-fiber and fiber-to-machine friction during spinning.In order to solve these deficiencies of nettle fiber,improve the softness of fiber,the thesis preliminarily modified the nettle fiber by three?traditional alkali method,amino silicone oil method and redox system grafted acrylic monomer?methods to reduce the rigidity of the fiber and improve the flexibility,and the problem of the nettle fiber spinning is solved.The results of single factor test of alkali method modification show that the fiber length becomes shorter and the diameter becomes thicker,the breaking strength firstly decreases and then tends to be stable,the breaking elongation increases firstly and then tends to be stable with the increase of alkali concentration,time and temperature.CCD response surface test to gain alkali treatment of nettle fiber is the best process:alkali concentration is 11.8 g/L,processing time is 90 min,and treatment temperature is 79°C.The average length of the nettle fiber treated by the process is reduced by26.67%,the whiteness is increased by 8.19%,the breaking strength is reduced by43.71%,the breaking elongation is increased by 51.14%,the moisture regain is increased by 13.59%,and the flexibility is increased by 42.04%.Scanning electron microscope?SEM?shows that after alkali treatment,the fiber surface is nicked,and the cross-sectional cell wall is full.The results of X-ray diffraction shows that the intercrystalline distance of the alkali-modified nettle fiber is increased and the crystallinity is decreased by 13.79%,indicating that after alkali treatment,the fiber surface becomes rough and the fiber rigidity is decreased.The results of single factor test of amino silicone oil modification show that the whiteness of the fiber is decreased,and the fracture strength is slightly decreased when the amino silicone oil content,treatment time,and treatment temperature increase.The breaking elongation and flexibility increase.The CCD response surface method shows that the optimum process for the soft treatment of nettle fiber with amino silicone oil is amino silicone oil dosage 9 mL/L,treatment time 35 min,and treatment temperature 30°C.With this process,the whiteness of the nettle fiber is reduced by12.44%,the breaking strength is reduced by 35.97%,the breaking elongation is increased by 31.43%,the moisture regain is decreased by 5.78%,and the flexibility is increased by 76.43%.Scanning electron microscopy?SEM?shows that the surface of the nettle fiber after the amino silicone oil is smooth.X-ray shows that the spacing of the crystal surface of the soft modified nettle fiber has increased and the crystallinity is decreased by 2.34%.From the infrared spectrum,it can be clearly seen that new characteristic peaks?Si-C?at 1282.7 cm-1 and 799.77 cm-1,indicating that the amino silicone molecules has been successfully adsorbed on the fiber surface.The results of the single factor test for the grafting of acrylic acid onto the redox system are the whiteness of the fiber decreased,the fracture strength is decreased firstly and then stabilized,and the breaking elongation is increased firstly and then tends to be stable with the increase of acrylic acid monomer concentration,redox system concentration,time and temperature.The optimum process of grafting modified nettle fiber by orthogonal test is as follows:acrylic acid monomer concentration is 2.2mol/L,sodium thiosulfate concentration is 50 g/L,ammonium persulfate concentration is 1.8 g/L,treatment time is 5.5 h,and treatment temperature is 55°C.With this process,the whiteness of nettle fiber decreases by 6.65%,the breaking strength is decreased by 31.83%,and the breaking extension is increased by27.14%,moisture regain is increased by 10.00%,flexibility is increased by 32.48%.Scanning electron microscopy?SEM?shows that the surface of the nettle fibers after graft modification is roughened by the increase of graft copolymer chains.X-ray analysis shows that the spacing of the crystal surface of the nettle fiber increases,the crystal structure of the fiber has not been changed before and after the graft modification,the crystallization peak is sharper,and the modified fiber has a more complete crystal structure,and the crystallinity of the fiber is increased by 0.35%.From the infrared spectrum,it can be clearly seen that the infrared spectrum of the modified nettle fiber shows a new characteristic peak?-C=O?appears at 1680 cm-1 in the infrared spectrum of the modified nettle fiber,indicating successful grafting.The three modified methods can improve the softness of fiber,in which the whiteness of alkali modified fiber is the most obvious,the crystallinity is the most significant,and the fiber breaking elongation and moisture regain are the most significant,indicating that the fiber rigidity has the most obvious change,but the alkali modification has the greatest damage to the fiber.By reducing the static and dynamic friction coefficient of the fiber,the softener modifier gives the smoothness of the touch to the touch of the fiber and the softness of the fine structure between the fibers.The rigidity of the fiber has no obvious change,but the flexibility of the fiber is the most obvious,the fiber damage is less and the fiber whiteness decreases most obviously.Grafting modification can also improve fiber softness to a certain extent,and it has little effect on fiber breaking strength.Amino silicone oil modification is a good method to modify softeners only from the influence of modifier on fiber properties. |
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