INTERACTIONS BETWEEN POLY (ETHYLENE TEREPHTHALATE) FIBER AND ORGANIC SOLVENTS

Abstract

Interactions between poly (ethylene terephthalate) (PET) fiber and several organic solvents are discussed with regard to the swelling behavior of PET fiber in these solvents. Organic solvents used were trichloroethylene and tetrachloroethylene which are important media for solvent dyeing and finishing, and methanol, ethanol, 1-propanol, acetone, chloroform, 1, 2-dichloroethane and 1, 1, 2-trichloroethane. Results obtained were as follows:(1) The diffusion rate of trichloroethylene, chloroform, 1, 2-dichloroethane or 1, 1, 2-trichloroethane in PET fiber changes in two steps, the first step where the diffusion coefficient is gradually increased by the change of the structure of PET fiber and the following step is constant. On the other hand, tetrachloroethylene, alcohols and acetone apparently show constant diffusion coefficients in the whole process of diffusion.(2) In the case of solvents accompanying the change of the structure of PET fiber in the diffusion process, diffusion coefficients at immersion time t=0 were obtained by extraporation, and they are compared with those of the rest solvents.(3) From the relationship between the diffusion coefficient or activation energy of diffusion of solvents and their molecular volume, interactions between PET fiber and solvent can be interpreted by polar interactions in which solvent behaves as proton donor and PET fiber proton acceptor, and dispersion force. Furthermore, diffusion behaviors of alcohols are clearly different from those of other solvents on account of associability. These results support the explanation for the swelling behavior assumed from the relation of the solubility parameter and dipole moment to the equilibrium swelling.(4) The increase of the diffusion coefficient in the diffusion process apparently depends only upon that of chain freedom caused by the relaxation of interchain bonds in PET fiber interacting with solvent. Besides, the swelling region of PET fiber in solvent and the relation of the activation energy of diffusion to the activation entropy of diffusion are also discussed.