The decreasing absorbance at 5.73 µ indicated the loss of carbonyl groups. The rate of decrease in this region was more or less uniform throughout the entire exposure for the linseed oil film. A slight increase in absorbance after a 2-hour exposure was noted for the dehydrated castor oil with a uniformly de-creasing rate for the remainder of the exposure.6. The loss of the individual groups as indicated by the infrared spectra agreed with the total weight loss of both oil films. This loss is apparently sustained by a breakdown of the film at several points-e.g., OH-group, CH2 groups in the chain, and carbonyl groups-and is greatly accelerated by the ultraviolet light in the presence of oxygen. The breakdown products are apparently highly volatile materials which escape and have not yet been identified.
Analyses of rosin size precipitates prepared at 25°and 60°C. showed a small difference in composition, explainable in terms of contamination of the precipitate made at the higher temperature with inorganic substances present at the time of its formation.Analyses of rosin size pre-cipitates prepared at 25°C. and of the same precipitates after aging for two and a half years at room temperature showed that the composition had changed in the following manner:an increase of 8 to 9% in oxygen, a decrease of 1 to 2% in carbon, and a decrease of 0.5% in hydrogen.
ROSINsize does not impart water resistance to paper if the treatment is carried out under conditions which subject the wet size precipitate to heat over an appreciable time (3, 10).However, except for a statement by Neugebauer (/) that temperature has no effect on the size precipitate' ash, there is no information concerning the effect of heat on size precipitate composition.
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