Carbon-fiber reinforced plastics which have been used as strong and high elastic modulus materials for light-weight structures can be utilized in new areas by coating a metal on their surface.
A copper electroplating method was examined for the metal coating, since the electric conductivity of carbon-fibers in the composite materials appeared to be good enough for this purpose.
The results obtained for the epoxide resin reinforced anisotropically with about 60vol% continuous carbon-fibers are as follows:
(1) Carbon-fiber reinforced plastics can be electroplated with copper under the almost same condition for usual metals in copper sulfate or copper pyrophosphate bath. The deposition of initial grains of copper occurs on carbon-fibers at the surface of the reinforced plastics. A certain thickness of the electroplated layer is necessary for covering the whole surface of the reinforced plastics.
(2) The adhesive force of the electroplated layer increases with increasing roughness of the substrate surface. In copper sulfate bath, a large adhesive force is obtained when the layer is electroplated at a low current density or at high temperatures. The smoothness of the electroplated surface decreases under the condition that a large adhesive force is obtained.
(3) The adhesive force increases extremely without a large increase of roughness of the plated surface by the chemical pretreatment such as immersing the substrate in conc. sulfuric acid or chromic acid mixture. The increase of adhesive force is due to the increase of surface area, activity and cleanness of carbon-fibers at the surface and to the anchor effect of penetrating sections of the plated layer.

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The scattering of tensile strength results from various causes. For example, it arises from the non-uniformity of metallurgical structures caused by imperfect mixing of constituent materials, nonmetallic inclusions and the change in cooling rate. Furthermore, the scattering due to the difference in shape and size of test specimens depends upon the degree of improvement of plants and machines and the human efforts (carefulness, etc.). Therefore, it may be possible to determine the scattering range from a comparatively small number of data if the impovement is proper. So we considered theoretically a method of estimating the mean value, the maximum or the upper value and the minimum or the lower value.
The result of our theoretical consideration shows that the mean value σ_M of tensile strength for specimens having the same shape and size can be estimated from (TS)_max and (TS)_min by the following equation.
σ_M=√(TS)_max·(TS)_min (1)
where (TS)_max and (TS)_min are the maximum and minimum values of tensile strength for the sample. Then, the upper value (σ_∞)_r, the lower value (σ_l)_r, the maximum value (σ_max)_r and the minimum value (σ_min)_r can be obtained by the following equations
(σ_∞)_r=σ_M(δ_∞)_r (σ_l)_r=σ_M/(δ_∞)_r} (2)
(σ_max)_r=σ_M(δ_max)_r (σ_min)_r=σ_M/(δ_max)_r} (3)
where (δ_∞)_r and (δ_max)_r are coefficients which depend on the appraisement quantity q for the tensile strength of specimens, the degree of human improvement r and the quality of samples.
In order to verify the above theoretical consideration, the estimated values were calculated from the experimental data on a few specimens (12 pieces) by means of eqs. (1) and (3), and compared with the estimated values by usual statistical techniques. The results of such comparative investigation on many specimens of different lengths (l=5.2, 13, 26, 39, 52, 78 and 104mm) are summarized as follows:
(1) As shown in Table II, the mean value σ_M for all samples except the ones with l=52mm lies within the 95% confidence interval for the arithmetic mean value σ. Consequently, σ_M and σ are regarded equal in practical applications.
(2) The values of (σ_max)_r and (σ_min)_r obtained from eq. (3) are quite comparable to those of σ+3s and σ-3s, where s is the standard deviation.
(3) The scattering range of the tensile strength tends to decrease as l becomes longer or shorter than 52mm.

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As a part of the study on sintering reactions, the thermal decomposition process of La(OH)₃ was investigated by using T.G.A., D.T.A. and X-ray diffraction method. From the results thus obtained, the detailed mechanism of the decomposition was inferred.
(1) The thermo-gravimetric curves of specimens were obtained in air, N₂, and CO₂ gas. The thermal decomposition curves showed two stages for La(OH)₃. The chemical reactions of these stages were determined as follow.
2La(OH)₃→2LaO(OH)+2H₂O (the initial stage)
2LaO(OH)→La₂O₃+H₂O (the second stage)
(2) These reactions were found to be first order in various atmospheres. The rate constants for these two decomposition stages in air of La(OH) were represented by
k=10¹⁶exp(-23000/RT) (the initial stage)
k=10²⁵exp(-42000/RT) (the second stage)
(3) It was recognized that La(OH)₃ became La₂O₃ at about 600°C in air. The lattice constants of La₂O₃ obtained were a=3.945Å, c=6.151Å.

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Darkening and fading characteristics of germanate glasses in the systems Na₂S-GeO₂ and Na₂S-B₂O₃-GeO₂ were investigated. These glasses darkened by irradiation of U.V. light and the darkening faded by heat treatment. The most effective wavelength for the darkening is found to be 460mμ. The degree of darking increases with increasing U.V. irradiation time and reaches a saturated value at about 60 minutes. However, it decreases with increasing Na₂S and B₂O₃ contents in the glasses.
The activation energy for fading process of all glasses used was obtained to be 9∼10kcal/mol from the plot of fading rate as a function of reciprocal temperature. It is suggested that the darkening and fading mechanism of the glass can be interpreted on the basis of an electronic conduction model.

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In separation of organic solutes from aqueous solution by reverse osmosis, a solute which is strongly sorbed by the cellulose acetate membrane exhibits poor reverse osmosis rejection. Therefore, the separation is determined primarily by the distribution of a solute between the membrane and the aqueous solution, or the quantity defined as distribution coefficient. In the present study, the regular solution theory was applied to the treatment of this distribution under the condition that the membrane is an immiscible organic phase. From this approach, the following expression was derived.
RTln(1-R')=v_i{(δ_w²-δ_m²)-2δ_i(δ_w-δ_m)}+lnv_w/v_m
where R' is solute rejection; v_i, molar volume of solute; δ, solubility parameter; v_w, molar volume of water; v_m, molar volume of gel membrane.
The suffixes i, w and m denote solute, aqueous phase and membrane, respectively. In this treatment, no specific mechanism was assumed, and the standard chemical potentials were chosen for the pure solutes in both phases. For the dissociated solute, the dissociation constant K_a was incorporated in the treatment of distribution coefficient.
As the result, in the case of high K_a, the relation of log(1-R')∝pK_a was expected to hold. The order of solute separation corresponds to the order of solute dissociation in the feed solution. The relations described above were confirmed experimentally.

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