The surface products on Be-Cu alloys prepared as secondary electron emisson surfaces are studied by the electron diffraction method by refering the values of emission yield measured simultaneously. The surface products and the values of the emission yield are plotted on temperature-pressure diagrams representing the conditions of the preparation of specimens (Fig. 2, 3, 4). The results show that the production of BeO, which occurs selectively under certain conditions, plays primarily important roll to give high emission yield to surfaces of Be-Cu alloys. It is also observed that the selective oxidation of Be is influenced sensitively by factors other than temperature and pressure, for example, by preheating in high vacuum and by existence of unkonown residual gas.
C. P. D. between Pt and Ag in various dielectric liquids is measured by the Zisman method. The change of the true C. P. D. produced by the immersion of the electrodes in the liquid is found by the method reported before and shows a close connection with the dipole moment of the liquid molecule. It is further found that the apparent C. P. D. consists not only of the true C. P. D. and the potential drop through the Ohmic leakage resistance of the liquid, but also of an unknown potential which is not included in the previously reported formula giving the true C. P. D.
Discussions are given on (1) under what condition the reflected multiple-beam interference fringes attain high contrast, and (2) if the condition is not fulfilled, how the contrast is weakened. As for the definition of the width, instead of the customary width for one half of the maximum intensity, the width where the intensity becomes 1/2 (Imax+Imin) is proposed as it is not only more reasonable but also that the formula for the width becomes much simpler.
The rate of deterioration of tensile strength can be considered as a measure for deter-mining the expectancy of useful life of rubber articles. In consequence, every existing stan-dard for rubber goods specifies the change of tensile strength in its aging test. Any method of treating data in the aging test, however, has been unsatisfactory, because it has no theore-tical foundation but only empirical background. In order to improve the method, an application of the theory on extremal quotient is attempted in this paper on the assumption that the tensile strength of rubber is distributed doubly exponentially. The result is that, since the distribution of quotient of two independent variates, each of which follows the doubly exponential distribution, has been found logistical, the mean of the quotients of random couples of measurements of tensile strength before and after aging gives the most reasonable measure for the late of aging. Concretely speaking, let the random measurements before aging be S11, S12……. S1n, and after aging be S21, S22, ……, S2n, then the reliable value for tensile decay would be obtained by averaging arithmetically the calculated values of S21/S11, S22/S12, ……, S2n/S1n Although this new method has several assumptions and approximations in itself, it is considered a theoretical approach to the aging test in every specification for which no regard to such a reasoning has ever been paid.
Thin films of oleic acid were prepared with Langmuir method and also by spreading it with a glass rod on Pb, Zn Cd, Sn, Sb, Ag, Ni, Fe, Cr, Al and Cu, and were examined by electron diffraction. It is concluded that the molecules of metallic oleates stand normal to the surfaces irrespective of the kind of metal though the arrangement of the molecules is somewhat imperfect on some metals. Among many cases examined, the arrangement on Cu is most perfectly maintained to the thickness of about 40 molecular layers.
The variation of ultrasonic velocity with temperature in polymethyl methacrylate and polystyrene polymers was measured in the range of 0_??_90°C, using the total reflection method at frequencies of 1.46, 4.38 and 7.30 MC. An abrupt change in slope was found in the velocity vs. temperature curves of both polymers. This transition temperature is independent of the frequency and agrees with the second order transition temperature determined from the thermal expansion measurement. In case of polymethyl methacrylate, a slow change in slope was also found near 15°C in the velocity-temperature curve as well as in the thermal expan-sion curve. For both polymers, the function ui/4.5/ρ (u: sound velocity, ρ: density) was found to be independent of temperature over the whole temperature range of the experiment. It is expected, therefore, that the ultrasonic velocity in high polymers is closely related to the intermolecular free volume, in the same manner as in liquids of low molecular weight. The free length between segments was determined from it and p, using Kincaid-Eyring theory with slight modification.