Preparation And Characterization Of Tunicate Cellulose Solution For Spinning

Lyotropic chiral nematic liquid crystal (N*-LC) of cellulose has a special spiralstructure, so that it has some unique optical properties, such as the circular dichroism,selective reflection and optical rotation etc. Therefore, cellulose can be applied notonly in the traditional areas as natural fiber materials, but also has wide applications inanti-counterfeiting materials, reflective color e-paper, painting, display materials andinfrared reflectance materials.In this thesis, we selected tunicate as a raw material to extract cellulose andprepared tunicate cellulose nanocrystal (T-CNs) by acid hydrolysis process. Polarizingoptical microscope (POM) observation indicated that T-CNs suspension can form theN*-LCs above a critical concentration. Aqueous T-CNs suspensions can be evaporatedto produce solid semitransparent T-CNs films that retain the self-assembled suspensioncan form the N*-LCs order formed in the suspension. UV-Vis-NIR analysis showedthat T-CNs films had selective reflection characters and the reflectance at near infraredregion up to55%. Therefore, we can develop a kind of functional material by usingT-CNs, which can selective infrared reflective.Because of intramolecular and intermolecular hydrogen bonds of cellulose, andcomplex aggregation structure and high crystallinity, cellulose cannot be dissolved incommon solvents. Therefore, the solvent and dissolution method became veryimportant problems in cellulose industry and basic research. In this research, tunicatecellulose was dissolved in lithium chloride/dimethylacetamide (LiCl/DMAc) solventsystem and1-allyl-3-methyl-imidazolechloride salt (AmimCl) solvent system, respectively. The properties of cellulose solution and the structure of regeneratedcellulose from tunicate cellulose were studied for the first time. The dissolutionprocess was observed by polarizing optical microscope (POM). It was found thattunicate cellulose was well dissolved in both of the solvent systems under certainconditions. The intra-and intermolecular hydrogen bonds of the celluloses was greatlydestroyed by high-power ultrasonic pretreatment. Solubility of the tunicate cellulosewas improved by increasing surface area between cellulose and solvent, meanwhiledecreasing the crystallinity and degree of polymerization of the tunicate cellulose. Thestructure and morphology of regenerated cellulose were characterized by using Fouriertransform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). It was showedthat cellulose dissolved in both of the solvent systems is direct dissolution mechanism.Dissolution and regeneration process without derivatives. The crystal form ofregenerated cellulose was transformed from I into II form.