No abstract

A comparative study of the tack of Butyl and natural rubbers was made by contacting freshly cut surfaces of the compounds under various time-temperature-pressure conditions and measuring the force required to separate the splice. The temperature of the knife used to cut the samples was found to be of primary importance. The tack of Butyl compounded with 50 parts of semireën-forcing carbon black (no curatives) decreases regularly with increasing knife temperature. Both longer time and higher pressure of contact favor better splicing. Data are presented on the effect of various plasticizers and carbon blacks on the tack of Butyl compounds.

point of acetonyi acetone cannot be utilized, however, because of the acidity of the phosphorylated compounds. This acidity is sufficient to cyclicize the compound to 2,5-dimethylfuran and hence the reaction temperature must be kept at 90°to 100°C. Table II shows results of treatment of phosphorylated materials with sodium iodide in acetonyi acetone. Sample 3 was prepared by treatment of hydroxyethylcellulose with phosphorus oxychloride in pyridine at room temperature for 35 days. The product contains 9.7% phosphorus which is approximately 9 times that contained in a phosphorylated cellulose prepared in the same manner.This may be due to the phosphorylation occurring in the hydroxyl group of the hydroxyethyl chain, which should be the most easily accessible. Since all samples underwent a replacement of part of the phosphorus and part of the chlorine, it appears probable that some of each is attached in the primary position. CONCLUSIONSThe combined phosphorus in cellulose phosphate prepared by treatment of cellulose with urea phosphate is probably entirely in the form of a monosubstituted phosphate ester. There is no evidence of formation of other, more highly substituted products, as presumed by Coppick and Hall (5).The structure of cellulose phosphate prepared by the treatment of cellulose with phosphorus oxychloride-pyridine mixture is similar, except that in a typical sample approximately 23% of the phosphorus can be accounted for as a disubstituted phos-