Quantifying Residual Coning Oils in Quantitative Viscose Content Determination
Unextracted coning oils add false mass to insoluble fiber fractions during quantitative chemical dissolution, distorting declared viscose blend percentages.
Viscose Polyester Blend Analysis
Quantitative Testing
Chemical separation and quantitative evaluation of the relative proportions of regenerated cellulose and synthetic polyester in a blended yarn or fabric represents a fundamental quality control requirement for textile laboratories. This viscose polyester blend analysis ensures that the material matches the fiber composition declared on garment labels and commercial invoices. Standard procedures utilize selective dissolution where one fiber type is dissolved while the other remains intact.
Laboratory Method
Implementing the analysis typically involves dissolving the viscose component using a formic acid and zinc chloride solution, or a sodium zincate solvent. The remaining polyester residue is then washed, dried, and weighed to calculate the precise percentage of each fiber in the original fabric sample. Careful temperature control during dissolution prevents the solvent from degrading the polyester component and skewing the final result.
Quality Check
Fabric mills and garment importers run these tests to verify compliance with fiber labeling regulations and trade agreements. Discrepancies between the declared blend ratio and the actual test result can lead to customs delays or heavy penalties.
Dyeing Calibration
Knowing the exact blend ratio is essential for calculating the correct dye formulations in the dyehouse, as viscose and polyester require different dye classes and temperatures.