Changes in the Infrared Absorbance and Color of Aged Cellulose Film

ABSTRACTThe accelerated aging of unplasticized Cellophane film specimens was conducted at tempe:atures ranging from 80 to 150 °C in a dry, forced-air convection oven for various periods of time. Colorimetric evaluation showed increasing discoloration which could be partially reversed by rinsing in deionized water. The infrared spectra of samples aged within this temperature range show the same changes, dependent upon aging time. This indicates that the species formed in the films at temperatures above and below the boiling point of water are the same, and that the moisture content of the films may affect the reaction rate, but not the mechanisms. The observed data in the visible region fit the standard pseudofirst-order kinetics model and are in excellent agreement with those determined for both the color change of cotton and the UV absorbance of Cellophane under similar conditions.

Effects of Swelling Treatments on Fine Structure and Mechanical Properties of Cellophane Film

Commercial cellophane film was studied, primarily with a view to determining structural modifications as a result of swelling treatments. Cellophane films were subjected to swelling in ethylenediamine, pyridine, and an aqueous solution of sodium hydroxide. Structural properties such as crystallinity and crystallite size were determined by x-ray diffraction. Changes in orientation were followed by determining birefringence and sonic velocity. Mechanical properties such as tensile strength, elongation, and tearing strength were also studied. An analysis of the data revealed that the swelling treatment increases the crystallinity, which improves the mechanical properties.