INTERACTION OF DYES USED FOR FOODS WITH FOOD-PACKAGING POLYESTER FIBERS

The effect of pH, temperature, dye concentration, and additives on the absorption of the dyes FD & C (Food, Drugs and Cosmetics) Blue 1 and Blue 2 upon poly(ethylene terephthalate) (PET) and poly(butylene terep hthalate) (PBT) subjected to different draw ratios (and, thus, resulti ng in different percentage crystallinities determined with DSC and wid e-angle X-ray diffraction patterns) was investigated and a correlation between these parameters and the dye uptake was suggested. The absorp tion kinetics of the dyes on the polyesters were studied and a mechani sm based upon the development of hydrogen bonds between the dyes and t he end groups (-COOH, - OH) of the polyesters and the swelling of the network was proposed. Finally, an indirect measurement of the T(g) val ues of the polyesters was suggested based upon the different dyeing di ffusion rates. (C) 1994 John Wiley & Sons, Inc.