Effect of Ultraviolet Light on Cellulose Acetate and Nitrate

Abstract

The effect of ultraviolet light on the viscosity of cellulose acetate and cellulose nitrate has been studied in atmospheres of air, nitrogen, and oxygen. In air and oxygen the degradation of these cellulose esters is accelerated. The effect of a nitrogen atmosphere is to retard degradation. In all atmospheres the drop in viscosity for cellulose acetate was gradual; for cellulose nitrate the viscosity dropped more rapidly during the initial part of exposure and then leveled off.

Physical-Mechanical Properties of Nitrodopes Affected by Ultra-Violet Radiation

“…In all other samples with the higher percentage of nitrocellulose, upon 240, 480 and 960- minute action of the UV-rays the decrease of the crosslinking degree, i.e. the degradation, has occurred which indicates that the photolysis has led to the breaking of bonds in macromolecules causing the deterioration of the physical-mechanical properties of the polymers [7, 8]. …”

“…Based on the diagram in Figure 2 and the collective graph in Figure 3, it can be observed that the limiting viscosity [η] and the mean molar mass M η rise with the increase of the nitrocellulose mass pecentage in a sample, and that their values decrease after the UV radiation, that is, the longer the radiation time period the lower the values of [η] and M η are [8;9]. …”

“…Table 1 indicates what happens to the viscosities of solution of samples of cellulose nitrate that are: (a) kept dark; (b) exposed to UV under nitrogen, and (c) exposed to UV in air for 200 hours. Clearly the additional presence of oxygen dramatically accelerates the light-induced decomposition [8]. …”

The instability of cellulose nitrate adhesives

“…The nitrogen content is diminished at all ultra-violet wavelengths and cleavage of the cellulose chains occurs, resulting in -a reduction in molecular weight (and thus viscosity). Control samples, stored in the dark at room temperature likewise degraded, but to a lesser extent 6 .…”

Photolysis of Nitrate Esters: Part I. Photonitration of Diphenylamine

“…The reactions postulated to account for the photoproducts paralleled those invoked for thermal decomposition where the initial, rate-determining step has been established as homolytic alkoxy-nitro bond fission (1,13,14). Photolysis of polynitrate esters in the condensed state also caused evolution of nitrogen and the oxides of carbon and nitrogen; the thermal stability of the explosive compounds was reduced and, for cellulose nitrate, depolymerization and oxidation occurred (15)(16)(17)(18)(19)(20)(21).…”