The aim of the study was to find out the relationship between the DP and the tensile properties of different regenerated cellulose fibers. During the process to make regenerated cellulose fibers from wood, the reduction in DP of cellulose is a necessary process to enable fiber extrusion. The reduction of the DP is usually from 1000 to 350 (Coley 1953). The reduction in DP is necessary, first to make the cellulose soluble, and then further decrease in DP is required to control the viscosity of the solution to minimize the mechanical difficulties during processing faced. It is a fact that the reduction in DP is a compromise which is necessary, as reduction in DP means reduction in tensile properties of the fiber produced. The reduction in DP is optimized to make the process both processing and the final product more feasible. The relation in DP and the strength of the fibers is rather obvious i.e. higher the DP higher the tensile strength, but researchers have different views regarding the relationship. By the experiments performed by us we tried to come to a conclusion regarding the difference in opinions. Different types of regenerated cellulose fibers were collected from various sources. Both wet and dry tenacities of 19 different viscose, bamboo viscose, kupro viscose, modal and Tencel fibers were determined. The fiber linear density was also measured, but for some samples we had to take the fiber density value as provided by the manufacturer, due to the limitation of the instrument regarding the fiber length and low fiber linear density. Then out of all the samples 10 were selected (based on our and company’s interest). SEC analysis was used to determine the DP of the samples. These tests were not carried out by us but by MoRe Research. The results of both the analysis were gathered, analyzed and commented upon. / Program: Master Programme in Textile Technology

The objectives of the research are to establish the process of obtaining regenerated fibers and films from wood pulp and bagasse pulp with the ionic liquid 1-Butyl-3-methylimidazolium Chloride (BMIMCl) as a solvent; to study the impacts on tensile strength of different spinning parameters; to find the optimal spinning condition, and to obtain regenerated cellulose products with flame retardant properties. Solutions were obtained by dissolving cellulose (wood/bagasse) pulp into the BMIMCl. The solutions were extruded in a dry-jet and wet-spinning method using water as a coagulation bath. The obtained fibers were tested to evaluate the properties such as tensile strength, thermal property, thermal mechanical property, crystal order, and ionic liquid residue in obtained fiber. The orthogonal experiments were designed to find out the strongest affective variable and the optimal condition of the spinning process. The regenerated cellulose films with melamine resin or zinc oxide were obtained. Their flame retardant properties were tested. Cellulose fiber with melamine resin was also obtained. Thermo-gravimetric analyzer (TGA) was used to measure the thermal properties of obtained products, and to calculate their activation energies. Dynamic mechanical analysis (DMA) was used to determine the thermal mechanical properties of obtained fibers. Wide angle X-ray diffraction (WAXD) was used to measure the degree of crystallinity and degree of crystal orientation. The tensile strength was tested by a tensile machine. To evaluate the quantity of ionic liquid residue in the regenerated fibers, the instrumental methods of FT-IR and Mass Spectrometry were applied. Research results indicated increases in the degree of crystallinity and storage modulus under a higher fiber drawing speed. Both regenerated bagasse fibers and regenerated wood fibers had similar thermal properties. However, the regenerated bagasse fibers showed a higher degree of crystallinity and a higher tenacity than the regenerated wood fibers obtained under the same condition. The study also revealed water treatment would be helpful for eliminating the ionic residue in regenerated fibers. It was also found the concentration of cellulose in the BMIMCl solution affected the tensile strength of regenerated fiber mostly. Certain amount of melamine or zinc oxide nanoparticles contained in the cellulose matrix could improve the flame retardant property effectively. / text