Study On Ramie Fibers Treated By NMMO

Although ramie fabrics have the advantage of stiffness, pleasantly coolness, moistureabsorbency and sweat releasing there are some shortcomings like prickle, wrinkling and poorproperties of elasticity and softness because ramie fibers have high degree of crystallinity andrigidity. N-methylmorpholine-N-Oxide (NMMO) was used to deal with ramie fibers for thepurpose of reducing degree of crystallinity and improving the properties in this paper. Because oflow degree of crystallinity ramie fibers have a wider amorphous region and the accessibility offibers has been increased in order that it is easily come into the molecules of the fibers for somefunctional groups. Moreover, the method of ramie fibers treated by NMMO may save resourcesand reduce the pollution of the environment. It has some importance of improving the propertiesof ramie fibers and clean production.The method of single factor experiment was used to investigate the effect of theconcentration of NMMO, temperature and time on the properties of ramie fibers. When thetemperature, time and the concentration of NMMO increased the breaking tenacity of ramie fibersdecreased and the breaking elongation and the breaking rotation number of ramie fibers increased.The optimum conditions of treating in NMMO were30%concentration at70℃temperature for30minutes.Based on single factor experiment, orthogonal experiment was designed to optimize theprocess of ramie fibers treated by NMMO. The results showed that the perfect properties of ramiefibers were reached when they were treated for20minutes in the30%concentration of NMMOsolution at the temperature of65℃. Under these conditions the breaking tenacity decreased by23.84%while the breaking elongation and breaking rotation number of ramie fibers increased by41.36%and57.53%respectively. The fibers had a better effect than the other experiments. Theresults of SEM showed that the fibers had a smoother surface and longitudinal cracks appeared onthe surface at a high concentration of NMMO. By FTIR spectroscopy it was confirmed that therewere not NMMO residue in the treated fibers, XRD showed that there were no new types of cellulose generated in it and the degree of crystallinity was decreased by21.08%.By the response surface analysis the relationship between the breaking tenacity, the breakingelongation, the breaking rotation numbers and the NMMO concentration, the temperature, thetime were studied. It was concluded that the properties had achieved their best when thetemperature was66.123℃, NMMO concentration was33.687%and the time were22.913minutes,the breaking tenacity, the breaking elongation and the breaking rotation number were5.03cN·dtex-1,4.26%and448times respectively.In order to reduce the usage of NMMO the ramie fibers were treated by the mixture ofsodium hydroxide and NMMO. It was found that the application of sodium hydroxide couldimprove the treatment and reduce to use the NMMO. With the increase of sodium hydroxide (orNMMO) concentration, the breaking tenacity of the fibers decreased while the breakingelongation and the breaking rotation numbers increased under constant NMMO (or sodiumhydroxide) concentration. The results showed the mixed solution of10%sodium hydroxide and10%NMMO had better effect in the treatment of ramie fibers.