Study On Quantitative Analysis Method Of Mercerized Cotton/Regenerated Cellulose Fibers

With the development of science and technology and the demands for comfort,more and more regenerated cellulose fibers was used in clothing processing byblended with cotton fibers. The blended fabrics are often mercerized to improve theperformance and reduce costs. The type and content of fibers in blended fabrics areimportant parameters. The most commonly quantitative analysis methods formercerized cotton/regenerated cellulose fibers are physical are formic acid/zincchloride method,59.5%sulfuric acid and mixed acid method. The application ofphysical method is subject to certain restrictions, because of time–consuming andinefficiency. Other three methods belong to chemical quantitative method,regenerated cellulose fibers with low degree of polymerization and crystallinity weredissolved, meantimes, cotton fibers with high degree of polymerization andcrystallinity was remained. However, the cotton fiber could be damaged duringdissolving process due to the similar structure with regenerated cellulose fiber.Quality correcting coefficient d was needed to correct the quality of cotton fiberwhich was not dissolved and after dissolved in order to obtain accurate quantitativeresults. Mercerize finishing cause damage for cotton fiber, and its microstructure andphysical and chemical properties changed. Especially the damage of mercerizedcotton increased in the current standards chemicals, while the standard did not makeclear explanation, resulting in inaccurate quantitation.In this paper, the properties of cotton fibers after mercerized and therelationship between the degrees of degradation and mercerized degrees were researched. Consequently seeking out right d to make it more accurate forquantitative analysis of mercerized cotton/regenerated cellulose fibers.The study found that when using formic acid/zinc chloride method, theoptimum conditions was that: the dissolution temperature was at70℃, dissolutiontime was at30min, and the bath ratio was1:100. For fully mercerized cotton fiber,quality correcting coefficient d was1.05. For inadequate mercerized cotton fiber andnot mercerized fiber, d were1.03. For other degree mercerized cotton fibers, itshould select the appropriate d based on mercerized degree. When using59.5%sulfuric acid method, stripping color could eliminate the effects of dyes and dyes hadno effect on the degree of mercerized cotton fiber, recycled fiber can generally becompletely dissolved. In the standard process, rayon could completely dissolve. Forthe insoluble regenerated fiber, it could be used30℃×50min, bath ratio of1:100,and the oscillation frequency of100times/min. For not mercerized cotton fiber, dwas1.06; lower degree of mercerized and not fully mercerized cotton fibers, d was1.08; full mercerized cotton fibers, d was1.12.By comparison test, improving d in the standards and dissolution conditionscould improve accuracy of the results for formic acid/zinc chloride and59.5%sulfuric acid methods.