High Pressure X-Ray Studies of Polymers. I. Pressure Calibration for the Diamond Anvil-Cell in the Range 0-15 kbars.

摘要

Pressure-volume data for hexamethylene tetramine up to 7 kbars was obtained using a dilatometer, combined with some data obtained by Bridgeman, and the total fitted to a quadratic function: Delta V = K sub 1 p-K sub 2 p square for pressures up to 15 kbars. A good fit was obtained, the constants obtained were 1C sub 1 = 9.77 x 10 to the -12th power sq cm/dyne and K2 = 2.16 x 10 to the -22nd power cm to the 4th power/sq dynes. Using this equation the interplanar spacings of the crystalline H.M.T. can be calculated as a function of pressure, and this provides a convenient and accurate method of pressure calibration for high pressure X-ray cameras based on the diamond cell technique. This method is particularly suitable for high pressure studies of polymers since for these materials the greatest interest is directed toward lower pressures. A comparison with other techniques reveals that this new method is significantly more accurate for pressures in the range 0-5 kbars. (Author)