Abstract
1. Plasticising effect of solidp lasticiser on the cellulose acetate film was examined. A point is found in the plastiser content and elongation curve, where the rate of increase in the plastic elongation makes a leap. This point just coincides with the content of the plasticiser (ca. 30%), at which the visible crystals begin to appear on the surface of the film.
2. Attempts are taken to study a form of combination between the cellulose acetate and plasticisers, by making cellulose acetate films to swell in the mediums of ethyl alcohol containing various amounts of plasticisers. The cellulose acetate film swells by alcohol only to a limitted degree, (so far as the circumstances remain to retain the original structure of the film, ) and the alcoholic gel of cellulose acetate thus formed acts apparently as a solvent against the plasticisers, and the plasticisers are distributed between the mediums and the cellulose acetate gel in accordance with the Henry's law of distribution.
And the plasticising efficiency of triacetine by the distribution method is examined.
3. By comparing the affinity to the cellulose acetate, the physico-chemical properties and the plasticising efficiency of certain plasticisers, it is recognised that the efficiency of plasticiser is greater as the affinity, viscosity and surface tension are greater.
4. From these experimental results, the increase of plasticity is ascribed to the permanent swollen state of the cellulose-acetate. In this stata the mutual cohesive power of the micelle is decreased by the intra micellar swelling, the spaces between the structual units is enlarged, and the slipping capability among the micelle or the structual units is increased by the “inner lubricating effect” of the plasticisers. July, 27th, 1931.
