234 



TABLES 224-229.— VALUES OF PHYSICAL CONSTANTS OF 

 DIFFERENT RUBBERS * 



Where a range is given, there are available several observations that differ. 

 In most cases the differences are thought to be real, arising from differences in 

 the rubber rather than from errors of observation. Where a single value is 

 given, it is either because no other observations are available or because there 

 seems to be no significant disagreement among values within the errors of 

 observation. The latter values are marked with an asterisk (*). Where no 

 values are given, no data have been found. Where dashes are shown, either 

 the physical measurement is impossible or the values obtained are not sig- 

 nificant. Values at 25 °C and 1 atmosphere pressure. 



Since these data were compiled from a number of sources, no specific 

 references are given. A list of references follows : 



Ball, J. M., and Maasen, G. C, American Society for Testing Materials Symposium 

 on the Applications of Synthetic Rubbers, March 2, 1944. Bekkedahl, Norman, 

 Natural rubbers — a general summary of their composition, properties, and uses, India Rub- 

 ber World, vol. 116, p. 57, 1947; also in Compounding ingredients for rubber, published by 

 India Rubber World, New York, 1947. Bekkedahl, N., and Roth, F. L., Unpublished 

 observations of density and expansivity, 1948. Boonstra, B. B. S. T., Properties of 

 elastomers, chap. 4 of vol. 3 of Elastomers and plastomers, their chemistry, physics, and 

 technology, edited by R. Houwink, Elsevier Publishing Co., New York, 1948. Dawson, 

 T. R., and Porritt, B. D., Rubber physical and chemical properties, Research Association 

 of British Rubber Manufacturers, Croydon, England, 1935. Dillon, J. H., Prettyman, 

 I. B., and Hall, G. L., Hysteretic and elastic properties of rubberlike materials under dy- 

 namic shear stresses, Journ. Appl. Phys., vol. 15, p. 309, 1944 ; Rubber Chem. Techn., vol. 

 17, p. 597, 1944. Hamill, W. H., Mrowca, B. A., and Anthony, R. L., Specific heats of 

 hevea, GR-S, and GR-I stocks, Ind. Eng. Chem., vol. 38, p. 106, 1946; Rubber Chem. 

 Techn., vol. 19, p. 622, 1946. Kemp, A. R., and Malm, F. S., Hard rubber (ebonite), 

 chap. 18 in Chemistry and technology of rubber, edited by C. C. Davis and J. T. Blake, 

 Reinhold Publishing Corporation, New York, 1937. Prettyman, I. B., Physical prop- 

 erties of natural and synthetic rubber stocks, Handbook of Chemistry and Physics, 30th ed., 

 p. 1301, Chemical Rubber Publishing Co., Cleveland, Ohio, 1947. Rands, Robert D., 

 Jr., Ferguson, W. Julian, and Prather, John L., Specific heat and increases of entropy 

 and enthalpy of the synthetic rubber GR-S from 0° to 330° K, Nat. Bur. Standards Journ. 

 Res., vol. 33, p. 63, 1944 (RP1595). Selker, Alan H., Scott, Arnold H., and McPher- 

 son, Archibald T., Electrical and mechanical properties of the system Buna S-Gilsonite, 

 Nat. Bur. Standards Journ. Res., vol. 31, p. 141, 1943 (RP1554). Wildschut, A. J., 

 Technological and physical investigations on natural and synthetic rubbers. Elsevier Pub- 

 lishing Co., New York, 1946. Wood, Lawrence A., Bekkedahl, Norman, and Roth, 

 Frank L., The measurement of densities of synthetic rubbers, Nat. Bur. Standards Journ. 

 Res., vol. 29, p. 391, 1942 (RP1507) ; Ind. Eng. Chem., vol. 34, p. 1291, 1942; Rubber Chem. 

 Techn., vol. 16, p. 244, 1943. Wood, L. A., and Tilton, L. W., Refractive index of 

 natural rubber at different wavelengths, Proc. Second Rubber Techn. Conf., p. 142 (Insti- 

 tution of the Rubber Industry, London), 1948; Nat. Bur. Standards Journ. Res., vol. 43. 

 p. 57, 1949 (RP2004). Wood, Lawrence A., Synthetic rubbers: a review of their 

 compositions, properties, and uses, Nat. Bur. Standards Circ. C427, 1940 ; Rubber Chem. 

 Techn., vol. 13, p. 861, 1940; India Rubber World, vol. 102, p. 33, 1940. Wood, 

 Lawrence A., Values of the physical constants of rubber, Proc. Rubber Techn. Conf., 

 p. 933 (Institution of the Rubber Industry, London), 1938; Rubber Chem. Techn., vol. 12, 

 p. 130, 1939. 



* Prepared by Lawrence A. Wood, National Bureau of Standards. 



SMITHSONIAN PHYSICAL TABLES 



