Thesis Details

Thesis Title: Causes of yellowing of bleached cotton fabrics
Thesis Author: Daniel Hunt
Abstract: Bleached cotton fabrics sometime have a tendency to turn yellow when stored for a period of time. All of the factors which are involved in the yellowing reactions are not known, but from a quallty standpoint, the importance of preventlng yellowing ls very easily understood. The purpose of this thesis has been to study the effects of several variables on yellowing of bleached cotton fabrics. Accelerated aging techniques were used in this thesis research because of the limited time factor involved. Two available aging techniques were used for comparative purposes. One test consisted of steaming fabr1cs in an autoclave for one hour, operating at 15 pounds pressure. The other consisted of heating fabrics in an oven for eighteen hours at 105 °C. A method based on the reflectance of blue and green light was used to measure yellowing which occurred during accelerated aging. from the blue and green reflectance values, a value for fabric whiteness was calculated using an equation which gives results which correlate well with what a normal observer sees. The difference in whiteness values which were calculated before and after aging represented the change in whiteness or the amount of yellowing that ooourred during aging. The results of the experimental work designed to determine a relationship between strength of 80x80 cotton print cloth and oxidative damage indicated that fabric strength was essentially constant until a fluidity of 8.0 to 9.0 was reached. At these values, fabric strength started to decrease rapidly.