Moisture regain measurements have been made at 25° C. and 79.3% relative humidity on non-acetylated and acetylated fibroin.The equilibrium moisture content of acetylated fibroin is slightly lower than that of non-acetylated fibroin and varies with the degree of acetylation.In the case of fibres acetylated by the action of acetic anhydride it is shown that the decrease in moisture content is not attributable to the action of liberated acetic acid.
am convinced by nineteen years of close association with scientists, although with no scientific education, that the greatest gift to the country, of research, and of the chemical 2ndustries, will be the spread of that scientific h,abit of thought zn the sal,u~tio~z of our national, our local and our personal p)-oblenzs, The search for truth shall set its f ree.&dquo; IIoN. FRANCIS
It is shown that the free amino and free hydroxyl groups of silk fibroin are blocked by treatment with ketene, 1 yielding a modified protein. The study of this ketcnized fibroin will be continued in this laboratory this coming year.
1. The study of the behavior of ketene towards silk fibroin has been continued. 2. The rate of absorption of ketene by fibroin increases with rise of temperature, and with increase of the concentration of ketene exposed to the fibre. 3. That ketene combines with the phenolic group of typosine, and the free α-amino groups in fibroin is evidenced by the failure of completely ketenized silk to respond to the characteristic Millon and Ninhydrin tests of protein respectively. 4. More ketene is absorbed by fibroin than can be accounted for by addition only in the known. phenolic and free amino groups. The results of acetyl analyses of fibroin, saturated with ketene, indicate the presence of other unidentified groupings in the protein molecule capable of combining with ketene. 5. The degree of acetylation of degummed silk fibroin reaches a maximum or limiting value of about 7% of acetyl groups. 6. Exhaustive treatment of silk fibroin with ketone gas produces a tan coloration of the fibre.
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