Study On Identification And Quantitative Analysis Of Melamine Fibers

First, according to the discrimination standard of fibers, melamine fibers are characterized for testing from studying the physical and chemical properties of melamine fibers in order to find out the characteristics of the fibers, and on this basis we can propose a identification path of melamine fiber. Melamine fiber is white, slightly rough feeling, with no significant chemical fiber characteristics; Under an optical microscope or a scanning electron microscope, longitudinal surface is uniform and smooth, no grooves and other features, the cross-section is oval or nearly circular, solid, non-lumen or medulla. Melamine fiber does not melt or burn near the flame contraction, change of its shape is small,and it does not produce a flame; redness in the flame, a small amount of smoke; leaving the flame it goes out immediately, there is a special taste, and the residue is black floc. In an alkaline reagent, at room temperature or under heating, it is not dissolved; insoluble in organic solvents; And it is insoluble nothing but concentrated sulfuric other acidic reagent at room temperature, but elevating temperatures the fibers can be dissolved in sulfuric acid and formic acid. Analysised by infrared spectrum and its main functional group is a C-N bond, C=N bond,-NH2 and triazine ring, 814cm-1 is characteristic absorption peak of the triazine ring. With the above features, we gradually exclude other fibers from the analyzes, combine with infrared spectra,identify the melamine fiber.Then according to the actual situation of melamine fiber blending application, analyze necessary conditions for the dissolution of melamine fiber in formic acid: formic acid concentrations is 60% above, the processing time of is less than 50 min, the treatment temperature remains is 90 ℃ above. The study found that acid-treated melamine fiber, as long as the dissolution occurs, becomes sticky, after filtering and dried residue becomes hard and brittle, the fiber has been destroyed.Melamine fiber quantitative analysis is based on the existing standard of quantitative chemical analysis, combined with chemical solubility of melamine fiber to carry out tests. When blended with cotton fibers: 90% formic acid, 90 ℃, oscillation, 1h, removing melamine fibers, d is 1.0207.When blended with viscose fibers: sodium zincate solution, room temperature, oscillation, 20 min, removing viscose fibers, d of the insoluble fiber is 1.0121. When blended with polyamide fibers: 80% formic acid, room temperature, oscillation, 15 min, removing polyamide fibers, d is 1.0031. When blended with the acrylic, dimethylformamide, 1h, oscillation, 90 ℃-95 ℃, removing acrylic fibers, d is 1.0143. When blended with polyester, phenol/tetrachloroethane, 10 min, 40℃, removing polyester, d is 1.0049. Since the melamine fibers have a strong resistance performance to chemical corrosion, During quantitative chemical analysis, dissolved and removed other blended fibers may be considered.