抄録
(1) Relation between The Effect of Wevelength and The Viscosity Behavior
DPs of two kinds of samples irradiated by λ 1850 A and λ 2537 A for different length of time, are determined by their viscosity of cuprammonium and nitrate-acetone solutions. Then, DP is plotted against time of exposure. The results show that in the case of λ 2537 A irradiation, the shapes of degradation curves obtained by these two measuring methods are substantially the same and that in the case of the λ 1850 A irradiation sample, the curve obtained by cuprammonium viscsity measurement gradually decreases with time of exposure, while the curve by nitrate-aceton viscosity method initially falls and hen becomes parallel to the axis of exposure time. These experimental facts lead to the conclusion that (1) on irradiation by λ 1850A in vacuum, direct scission of cellulose chain molecule by photchemical primary dissociation predominates at the initial stage of degradation, but during prolonged exposure, the formation of alkali sensitive linkage by intramolecular bond breaking is the main reaction, and (2) on the other hand, irradiation by λ 2537 A in oxygen atmosphere degrades cellulose without formation of alkali sensitive linkages.
(2) After Effect of Photodegradation of Cellulose
The after effect of photodegradation of cellulose by λ 1850 A a nd by λ 2537 A irradiation is examined during the storage in oxygen atmosphere and in vacuum desicator. In both cases, 4-hour irradiation is employed.
The results show that there is no after effect in each case within 20 days, contrary to the van Nostrand's findings.
(3) Effect of Light Intensity upon Photodegradation of Cellulose
Effect of light intensity upon initial stage of photodegpadation of cellulose has been reported for two different wavelengthsn, i.e., λ 1850 A and λ 2537 A. The number of scission per molecule is used as a measure of photodegradation, and R/I and R/√I are calculated, where R is the rate of photodegradation and I the light intensity. It was found that in both cases, only R/I gives a constant value in various light intensities, indicating that the rate of photodegradation is proportional to the light intensity I and not to √I.
