The Effect Of Flexible Chains On The Properties Of Cellulose Liquid Crystals And The Preparation Of High Strength Cellulose Fibers

Cellulose liquid crystal is one of the most important fields in the research of cellulose and can obtain cellulose fibers with high strength,which has attracted the attention of researchers.In this study,4-(co-(methylimidazolium)alkyloxy)-4'-(cyano)-biphenyl with 4,5 and 6 methylene groups was synthesized by hydrogen bonding.The effects of methylene on liquid crystal properties was studied as well as the rheological and liquid crystallinity and crystal phase transition of liquid crystal solutions,and cellulose fibers were prepared by dry-wet spinning.The specific research were as follows:The liquid crystal intermediates were synthesized by using cyanobiphenol and 1,4-dibromobutane,1,5-dibromopentane and 1,6-dibromohexane,and then liquid crystal primers were synthesized by adding N-methylimidazole.The structure of liquid crystal intermediate and liquid crystal primers were studied by NMR and FTIR.The purity of liquid crystal intermediate and liquid crystal primers were studied by liquid chromatography.The purity of liquid crystal intermediates were 98.07%,99.7%and 94.7%(n=4-6).The purity of the liquid crystal primers were 99.31%,100%and 98.13%(n=4-6).The interaction between the liquid crystal primers and the ionic liquid was studied by infrared spectroscopy.The results showed that there was no chemical reaction between the liquid crystal primers and the ioinc liquid,and they were combined by physical force.The effect of methylene on the performance of the liquid crystal was investigated by a scatterometer.The results showed that the volume fraction of rod-like particles in solution was the largest whenn n=5,which was not conducive to the formation of liquid crystal phase.In addition,When methylene was odd,poor coupling and low critical concentration and easy to tangle were also not conducive to the formation of liquid crystal phase.The deviation of the COX-MERZ rule indicated that there was a hydrogen bond interaction between the cellulose and the liquid crystal primers.The results of POM,XRD,and DSC showed that when n=4,the texture of the liquid crystal was fan-like texture,and the small peaks were 3.3 A and 9.7 A when the phase transition temperature changed from 70? to 85?.respectively.The magnetic field had been used to study the phase transition of liquid crystal.When the temperature changed from 70? to 80?,and the magnetic field intensity changed from 70(A/m)to 80(A/m),the texture of the liquid crystal was spherical texture.The temperature-dependence infrared results showed that hydrogen bond was formed between cellulose and liquid crystal primers when n=4 and n=6.The results of scanning electron microscopy(SEM)and electron monofiber force meter(TES)on pure cellulose fibers and fibers prepared from liquid-crystalline solutions showed that the surface of liquid-crystal fibers were smooth and.the mechanical strength were increased by 35.6%and 40%respectively compared with that of pure cellulose fibers.