278 Fibre Chemistry, Vol. 36, No.4, 2004 PHYSICAL CHEMISTRY OF FIBRE-FORMING POLYMERS SPECTRAL STUDY OF THE STATE OF DYES IN CHEMICAL FIBRES N. P. Zarubina,* L. K. Zavadskaya,** UDC 677.016:543.422 and F. Yu. Telegin* The results of the study show that the use of the diffuse reflection spectrum of dyed fibre materials can be used to obtain quantitative information on the electron absorption spectra of dyes in the sorbed state. In analyzing the concentration curve of the absorption spectra of vat dyes on polyester fabric, aggregation of the dyes inside the polymeric material was found. The study of coloration of polyamide fibre revealed the appearance of polar and nonpolar interactions of the sorbed molecules of acid dyes with the polymer substrate. Fabrication of textile materials with high dye coloristic and strength indexes of dyes requires studying the state in the fibre substrate [1, 2]. Spectrophotometric analysis of the light absorption of dyed films simulating chemical fibres is the most common method of investigating the characteristics of formation of color in polymeric materials [2, 3]. However, the features of the supramolecular structure of polymer films cause difficulties in using the results of such studies for fibre materials. Diffusion reflection spectroscopy, which examines the spectral characteristics of reflection, absorption, and scattering of light, makes it possible to study dye compounds on the surface or in the structure of the material and directly in the form of powder or deposit. This method has been actively used and elaborated in analytical chemistry [4, 5]. It is necessary to note that the science on the color of materials is based on measuring the diffuse reflection of light from a dyed material [6] and was developed several decades ago. However, in describing color and its subjective perception, only three-dimensional colorimetric characteristics, which are an integral function of the reflection spectrum, are used. The study of the spectral characteristics of light absorption using diffuse reflection spectroscopy significantly expands the boundaries of the traditional analytical methods of investigation of organic compounds, sorbents, and processes involving them. The possibility of systematically using the method of diffuse reflection spectroscopy for analyzing the characteristics of the light absorption of dyed fibre materials and establishing the possibility of spectral investigation of the state of dyes of different nature in polyester and polyamide fibres is discussed. Samples of twill-weave polyester cloth and polyamide fibre in the form of industrial cord thread manufactured by Shchekino Khimvolokno Combine were used for the study. The samples of polyester cloth dyed with the suspension method in laboratory conditions were taken from the data base of Ivanovo Scientific-Research Textile Institute. The samples of polyamide fibre were dyed with acid dyes in model conditions at a constant temperature of 60°C for 1 h at a bath ratio of 625 in a Linitest laboratory dyeing unit. The spectral studies of absorption of solutions of vat and acid dyes in water and organic solvents were conducted on U-2001 (Hitachi) and SF-10 recording spectrophotometers. The diffuse reflection spectra of the dyed fabrics, polyamide fibre, and dye powders were recorded with a Color Graph TM spectrophotometer (Milton Roy Co.). For comparing the spectral characteristics of absorption of the dyes, solutions of vat dyes in morpholine and dimethylsulfoxide (DMSO) and *Ivanovo State Chemical Engineering University; **Ivanovo Scientific-Research Textile Institute of the Cotton Industry. Translated from Khimicheskie Volokna, No. 4, pp. 36-39, JulyAugust, 2004. 0015-0541/04/3604-0278 © 2004 Springer Science+Business Media, Inc.