Residual Stress in Siliceous Glass Between Mullite Crystals

A birefringence of siliceous glass, which is coexisting with mullite crystals, was studied by an optical polarizing microscope. The cause of the birefringence was assumed to be the residual stress induced by a large contraction difference between the mullite and glass on cooling. The stress has been evaluated to be as high as—0.3 GPa, and to correspond to the elastic one which began to develop at the glass transition point.     

Different feeding and gustatory responses to ecdysone and 20-hydroxyecdysone by larvae of the silkworm,Bombyx mori

The feeding and gustatory responses to ecdysone and 20-hydroxyecdysone were investigated in the silkworm,Bombyx mori. 20-Hydroxyecdysone reduced feeding response strongly in fourth- and fifth-instar larvae, whereas ecdysone had no effect on feeding response. 20-Hydroxyecdysone stimulated the R receptor, the receptor to feeding deterrents, to a great degree. By contrast, ecdysone was much less effective for stimulating the R receptor. These results indicate that ecdysone and 20-hydroxyecdysone have different effects on feeding response due to different interactions with mouthpart chemoreceptors.     

Adhesive properties of cured epoxide resin containing the intermolecular compound of 2,4-diamino-6-vinyl-s-triazine and isocyanuric acid

The intermolecular compound of 2,4-diamino-6-vinyl-s-triazine and isocyanuric acid was synthesized, and the glass transition temperature and the adhesive properties of the cured epoxide resin containing the above compound were studied. Epoxide reacted with amino groups of 2,4-diamino-6-vinyl-s-triazine and isocyanuric acid at the curing conditions of 150 to 180°C for 60 min and formed the cured compounds. The infrared spectra showed that epoxide reacted with isocyanuric acid in the presence of imidazole compounds and converted to 2-oxazolidinone compound on the curing process. The glass transition temperatures of the cured compounds having isocyanurate and 2-oxazolidinone rings in their structures were higher than that of the epoxide resin cured with imidazole and rise as the curing temperature rises, but fall as 2-oxazolidinone ring content increases in their cured compounds. The tensile shear and peel strengths of the steel and steel bonded with the cured compounds and the cured epoxide resin were measured at 25 and 150°C. The adhesive strengths were improved due to isocyanurate and 2-oxazolidinone rings formed in their cured compounds.     

Studies on biaxial stretching of polypropylene film. IX. Melting behavior of biaxially stretched film in one step

Melting temperature of a film biaxially stretched in one step in air at 152 or 140°C increases with increase of vA, whereas heat of fusion and density decrease with increase of vA, where vA is the degree of stretching in area. The rapid decrease in density occurs for vA > 10. Extrapolation of the plot of the density versus vA^?1/2 gives a value of 0.870 g/cm³ at infinite vA, which has been reported as the amorphous density of isotactic polypropylene by Farrow. This is so because the fine structure of the film becomes more and more amorphous with further stretching and reaches completely amorphous state at infinite vA. The temperature of stretching has a strong effect on the thermal behavior of a film; a low stretching temperature (140°C) brings about lower melting temperature, heat of fusion, and density. Crystallinity after melt press has not so large an effect on the melting behavior as the stretching temperature. Melting temperature and the shape of the thermogram also depend on the heating rate. There is an appropriate heating rate depending on vA which gives the minimum melting temperature. With stretched samples, a small side peak or a shoulder appears at a relatively low temperature in the thermogram when a high heating rate is used.     

Fat splitting by the twitchell process at low temperature

Summary A study was made of the degree of splitting of coconut and soybean oils by the Twitchell process at 35±0.1°C. with no shaking or stirring, using an agent consisting mainly of tetrabutyl naphthalene sulfonic acid with water or dilute sulfuric acid. The degree of splitting was greater with sulfuric acid than with water. In general, the degree of splitting of soybean oil was greater when the sulfonic acid was dissolved in the oil layer than when it was in water. The reverse was true with coconut oil. Although addition of glycerol had no effect on the degree of splitting, addition of glacial acetic acid to the coconut oil system decreased fat splitting to a considerable extent. Addition of coconut fatty acids to the coconut oil system had little effect, but soybean fatty acids added to the soybean oil system markedly increased the degree of splitting. For the first time it has been demonstrated that, at 35±0.1°C., splitting of a fat by the Twitchell process occurs in a stepwise way. Coconut oil in contact with 1N sulfuric acid containing the sulfonic acid, corresponding to 1% by the weight of the oil, was about 90% split in 15 to 30 days, depending on the area of contact of the two layers. The diglyceride concentration reached a maximum during the early days of the reaction and then decreased somewhat. Monoglyceride concentration appeared to reach a maximum more slowly and then continued at that level as the concentrations of free fatty acids and glycerol steadily increased. Presented at the symposia on fat of the Chemical Society of Japan, Nov. 10, 1954, and Nov. 8, 1955, Nagoya, Japan; and the 8th annual meeting of the Chemical Society of Japan, Apr. 2, 1955, Tokyo, Japan.     

A Practical Model for the Interactions Between Hydrating Portland Cements and Poly-β-Naphthalene Sulfonate Condensate Superplasticizers

The performance of poly-β-naphthalene sulfonate condensate superplasticizer (BNS) as a dispersant for cement in concrete is affected severely by slight differences in the characteristics of the cement. In order to be able to predict these effects, a model for estimating the fluidity of cement paste containing BNS is proposed. This model is based on an assumption that the fluidity of cement paste is proportional to the BNS adsorption amount per surface area of hydrated cement (Ad/Hy). BNS is known to show two types of sorption on hydrated cement: one is the bulk absorption into initial hydrates and the other one is the superficial adsorption onto hydrates. Only the superficially adsorbed BNS is expected to work as a dispersant. By assuming a competitive Langmuir-type adsorption on hydrates between BNS and SO₄²⁻, a simple method to estimate Ad/Hy is developed, with the concentrations of BNS and SO₄²⁻ as the only two independent parameters. The resulting estimates of Ad/Hy show a good correlation with paste flow and its change with elapsed time for a broad range of cements. The SO₄²⁻ concentration in the aqueous phase of the cement paste just after the beginning of the mixing is known to affect the performance of BNS as a dispersant. By using the proposed model to discriminate between the superficial adsorption and bulk absorption of BNS, this phenomenon is explained quantitatively.     

高速气流冲击式粉体表面改性装置——HYBRIDIZATION系统及应用

利用高速气流冲击法进行粉体/粉体系表面改性技术,是迄今为止各种粉体材料开发中最为引人注目的技术之一。HYBRIDIZATION(下称HYB)系统是利用高速气流冲击法对微粉体进行干式/机械化处理,是使材料复合化的最实用的装置,可对各类有机物、无机物、金属等进行广泛组合,通用性很强,适用于许多行业领域。从本文所述的系统构成、型式,有关的典型球形化处理的运转特性,利用复合化高温粉体测定被处理粉体表面温度,利用颜料改变色调等的处理特点及该系统的适用性等(一部分是从已发表的学术论文及专利上摘录的),可以说明HYB系统的概况。     

The effect of annealing on mechanical and tribological properties of diamond-like carbon multilayer films

The diamond-like carbon (DLC) multilayer films have been deposited by plasma CVD deposition onSi wafer substrate. The deposited films have then been post-annealed in vacuum at 250 °C for 2 h. Changes in internal stress, hardness, critical load, friction coefficient and wear have been investigated toassess the influence of annealing on mechanical and tribological properties of DLC multilayer films. At the same time, DLC single layerfilms are also deposited and annealed in the same method for a comparison.The results show that there is 28–33% decrease in internal stress and 10–13% decrease in hardness of theDLC single layer films after the anneal treatment. However, for the DLC multilayer films, there is 41–43% decreasein internal stress and less than 2% decrease in hardness. In addition, the annealed DLC multilayer filmhas the same friction and wear properties as that un-annealed film. This result indicates that the anneal treatment isan effective method for the DLC multilayer films to reduce the internal stress and to increase the critical load.The by-effect of the annealing, decrease of hardness and wear resistance of the multilayer film, can be restrictedby the multilayer structure.     

Solubility of Si3N4 in Liquid SiO2

The nitrogen solubility in the SiO₂-rich liquid in the metastable binary SiO₂-Si₃N₄ system has been determined by analytical TEM to be 1%–4% of N/(O + N) at 1973–2223 K. Analysis of the near edge structure of the electron energy loss peak indicates that nitrogen is incorporated into the silicate network rather than being present as molecular N₂. A regular solution model with a positive enthalpy of mixing for the liquid was used to match the data for the metastable solubility of N in the presence of crystalline Si₃N₄ and to adjust the computed phase diagram. The solubility of Si₃N₄ in fused SiO₂ is far less than reported in liquid silicates also containing Al, Mg, and/or Y. Apparently, these cations act as modifiers that break anion bridges in the silicate network and, thereby, allow further incorporation of Si₃N₄ without prohibitive amounts of network cross-linking. Finally, indications emerged regarding the diffuse nature of the Si₃N₄-SiO₂ interface that leads to amorphous regions of higher N content.