Measurement of kappa number variability on the fiber level.Application: This new tool for measuring kappa number The Kappa number is an indication of the lignin content or bleachability of pulp. It measures the amount of bleach required during digestion of a wood pulp (part of the process of paper making) in order to obtain a pulp with agiven degree of whiteness. distributions can help improve the uniformity of pulp. The fiber kappa number distribution of pulp may have a substantial impact on pulp properties and processing costs. Traditionally, methods of measuring the kappa number distribution have been tedious, requiring a considerable effort in the lab to process a single sample. Previous work at the University of Washington yielded a fluorescence microscopy Noun 1. fluorescence microscopy - light microscopy in which the specimen is irradiated at wavelengths that excite fluorochromes microscopy - research with the use of microscopes method for measuring the kappa number of a single fiber. This method has now been incorporated into a flow-through instrument that can measure the kappa numbers of thousands of fibers in a period of minutes. Initial applications of the instrument showed that commercial pulps tend to have kappa number distributions that are significantly wider than those of carefully prepared laboratory pulps. Chip thickness was identified as a contributor to variability in kappa number, as predicted by a diffusion-limited model of pulping. One study suggested that anthraquinone anthraquinone /an·thra·quin·one/ (an?thrah-kwin´on) 1. the 9,10 quinone derivative of anthracene, used in dye manufacture. 2. any of the derivatives of this compound, some of which are dyes. improves lignin lignin (lĭg`nĭn), a highly polymerized and complex chemical compound especially common in woody plants. The cellulose walls of the wood become impregnated with lignin, a process called lignification, which greatly increases the strength and reactivity at the end of a kraft cook, allowing delignification to continue at a high rate for the low-kappa-number fibers in the distribution. In non-AQ cooks, the kappa number distribution tends to narrow as the cook progresses, and the delignification rate slows in the fibers el low kappa number. Robinson was with the University of Washington when the research was conducted, he is now with Capstone Technology, 5470 Shilshole Ave N.W., Ste. 420, Seattle, WA 98107. Gustafson is with the College of Forest Resources, University of Washington, P.O. Box 352100, Seattle, WA 98195-2100. Callis is with the University of Washington, Dept. of Chemistry, Box 351700 Seattle, WA 98195-1700. Bruckner was with the UW dept of Chemistry at the time of the research, he is now with Par Allele allele (əlēl`): see genetics. allele Any one of two or more alternative forms of a gene that may occur alternatively at a given site on a chromosome. Bioscience 384 Oyster Pt. Blvd, Ste. 8 South San Francisco South San Francisco, city (1990 pop. 54,312), San Mateo co., W Calif.; inc. 1908. South San Francisco has several industrial parks; its manufactures include medical supplies and equipment, foods, paint, paper products, consumer goods, and clothing. , CA 94040. Email Robinson at jrobinson@capstonetechnology.com |
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