The considerations that influence the selection of polymers and spmning conditions for the purpose of preparing a high-strength, low-elongation type of polyvinyl alcohol fiber for use as a reinforcing component in rigid, cold-hardening resins are discussed. A number of polyvinyl alcohol products from commercial sources were spun, and their fibers evaluated. The two products that gave the best over-all results yielded fibers with a tensde strength of 9-10 g/den and a breaking elongation of 4.5-5%. Elongations at break as small as 3.5% were obtamed with two low-molecular-weight samples. ' To attain optimum values of strength and stiffness with any polyvinyl alcohol, a careful build-up of the fiber fine structure is necessary. This was brought about in wet spinning by slowing down fiber coagulation, as well as other processing steps.
It is very useful to employ ion‐exchanging chromatography papers for a rapid separation of a mixture of amino acids. Various separations are described, in some cases taking only one hour. Special papers were developed for this purpose based on chemical modification of cellulose and containing basic or acid groups. The possibilities for using these papers in a quantitative determination are discussed.
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