無機高分子物質の多くは, 分子構造にもとづく物性が有機高分子と無機ガラスの中間に位置する. その代表的なものとしてNa₂O-P₂O₅系ガラスを選び, ガラス転移温度付近における応力緩和現象を研究した. Na₂O-P₂O₅系ガラスは, メタ組成をさかいとして, 橋かけ構造をとるウルトラ領域と, 鎖状構造をとるポリ領域に分けられる. 試料をこれらの組成領域に分類し, 一定温度における応力の時間変化を, 約10¹¹から10⁶dyn/cm²の範囲で約10³秒間測定した. 試料は, 歪が微少ならば線形粘弾性を示す. 応力が10⁷dyn/cm²より大きいところでは, 時間-温度の重ね合せは有効である. 移動因子-温度の関係は, ポリ領域ではWLF式に近く, 架橋密度の大きくなるにつれて, これからずれてくる. 10⁷dyn/cm²より小さい範囲では, 重ね合せは成立せず, 緩和曲線に屈曲 (擬ゴム状平坦) があらわれる. 緩和スペクトルの幅はウルトラ領域において架橋密度が増大すると (3次元性が増大すると) 狭くなってゆき, これは有機高分子における理論と一致する. 当然のことながら, ポリ領域において平均重合度が減少すれば, スペクトルの幅は狭くなる. ウルトラ領域での緩和スペクトルは, 短時間側に大きなもの, 長時間側に小さなものがあらわれる. 前者はWLF型であることから, 骨格分子のミクロブラウン運動を反映した物理的緩和, 後者は重ね合せが成り立たないことから, 分子の切断, 再結合を反映した化学的緩和であると考えられる. ポリ領域では高い温度になると結晶化が著しくなり, 低い応力の範囲は測定できない. しかし, 最大緩和時間の対数と平均重合度の対数の関係は直線的であり, この傾きが約1.5であることから, ポリ領域では, 分子と分子のからみ合いによる流動は生じていないことがわかった. ウルトラ領域において見られた擬ゴム状平坦は, 有機高分子におけるゴム弾性現像とは異なり, 流動領域における最大緩和時間と温度の関係はアーレニウス性を示す. このことから, 流動領域ではまず結合強度の弱い架橋点が切断-再結合し, 次に (より高い温度で) 鎖状骨格の一部分が切断-再結合して, 応力が緩和してゆく過程をたどるものと考えられる. 擬ゴム状平坦の大きさと架橋点間分子量との関係にゴム弾性論を適用すると, ガラス状態を形成する骨格分子は, 数Åの周期をもった螺旋状の構造をとることになる.

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An effect of grinding on the negative charges of the clay minerals has been studied, paying attention to the distribution of the charges on basal and edge surfaces.
The negative charges on the basal surface resulting from the isomorphous substitution were assessed from the C. E. C. values at pH 4, whereas those on the edge surfaces which vary with pH values of the ambient aqueous media were computed from the difference in C. E. C. values at pH 10 and pH 4.
Dickte from Hiraki-mine and kaolinite (Soft Georgia kaolin), chosen as samples, were dry ground or wet milled. Dry grinding produced particles on which the edge surfaces occupied a relatively greater proportion of the total surface area.
The obtained conclusions are as follows.
1. The negative charge densities on edge-faces of the ground samples were larger than those on basal surfaces.
2. The negative charge densities decreased gradually as grinding proceeded, which may suggest that the isomorphous substitution diminishes from the outermost surfaces toward the interior of the unground particles.

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ホットプレス法による緻密化理論に関しては, ニュートンおよびビンガム流体中の球状閉気孔が外圧により収縮するとして, その理論式がMurrayらにより誘導され, 現在までに多くの実証実験が報告されている. しかし, その理論式の妥当性に関するこれら実証は, 本来, 理論式を誘導するに際して, 採用された球状閉気孔のモデルを逸脱した連続開気孔が, 全気孔の大半を占めるような系で行なわれており, 物理的意味の点から疑問がある. 著者らは, ホットプレス緻密化の全領域において, 連続した一定形状の気孔が, 一定方向に配向した系の緻密化理論式 (Eq. 7) を誘導し, 実際に, 径の揃ったガラス繊維を配向, 充填させた系を用いて実験を行ない, この理論式の妥当性を検討した.

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1. The processes in the solid state reaction on the formation of perovskite type Pb(Mg_1/3Nb_2/3)O₃ from its component oxides have been investigated by a powder X-ray diffraction measurement. As a result, it is found that pyrochlore phase exists in three types, and that an interchange of these phases occurs at about 790°C, accompanied with the melting phenomena.
2. In the formation of the perovskite type, it seems that there are two processes involving the solid reaction on the bases of 2PbO⋅Nb₂O₅ and 3PbO⋅Nb₂O₅, respectively, and the composition of the product from 3:1:1 mixture (PbO:Nb₂O₅:MgO in molecular ratio) is an intermediate state of these in the two processes. Lattice constant of rhombohedral pyrochlore phase gradually approaches that of cubic one as the amount of Pb substituted by Mg increases, and the transformation to cubic type is completed in the substituted amount about five mole per cent, and above this amount the substitution by Mg does not occur.
3. When MgO contained in the mixture is in excess (e.g., 3:1:1.2), the amount of PbO volatilized decreases, and simultaneously the yield of perovskite increases. It is considered that the existence of excess MgO promotes the reactivity of MgO to the (NbO₃) network and drives the free PbO into the stable lattice.
4. By the hydrothermal treatment, cubic pyrochlore is obtained at relatively low temperature although no perovskite is formed.
5. For tetragonal pyrochlore, two atomic configurations are hypothetically suggested. Based on these configurations, the calculated powder X-ray patterns are compared with the observed one. It is concluded that the network-vacant configuration is more probable.

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The glass having fluor-richterite (Na⋅NaCa-Mg₅⋅Si₈:O₂₂F₂) composition was crystallized by various heat treatments and the relation between microstructure and bending strength of the crystallized material was studied. The results obtained were as follows:
1) The difference of microstructure between the outer surface and the internal part of the crystallized material was observed. A small amount of enstatite coexisted with fluor-richterite (main crystalline phase) on the surface, whereas only fluor-richterite was found in the internal part.
2) The amount of crystalline phase and the crystallite size varied with the heat-treating conditions.
3) Microcracks formed on the surface of the specimen when it was heated up to crystallization temperature at a comparatively high heating rate.
4) Secondary grain growth of fluor-richterite crystalline particle occurred during the heat treatment for crystal growth at a comparatively high temperature.
5) The bending strength of the crystallized material decreased with the increase of crystallite size. However, no quantitative relation between them was obtained, presumably due to the influences of microcrack and inhomogeneity of the microstructure resulting from secondary crystal growth.

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Factors, which essentially govern properties of casting slips, seemed to be the distribution of size and shape of particles, their surface activities and their dispersion states. If we could determine appropriate fundamental parameters to these factors, and if we could understand relationships between fundamental parameters and practical properties of casting slips, we could make more progress in casting slip control. As fundamental parameters, the author chose the solid fraction of dry bodies (F₃), the effective specific surface area for water movement through cast bodies (S_a), and the hydration degree of solid surfaces (d_s). The practical testing methods of these parameters were introduced and variation of their values for various conditions were discussed. The results were as follows.
1) F₃ which relates to the arrangement of particles in cast bodies was much influenced by the particle size distribution and the dispersion state.
2) S_a which could be determined from the casting rate of the slip on the basis of the equation by Adcock et al. was also influenced by the fineness and the dispersion state.
3) d_s could be calculated from the moisture content of cast bodies, and their values decreased with increasing degree of deflocculation.

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