Ground Mixture Research Articles

Microstructural investigation of CaTiO 3 formed mechanochemically by dry grinding of a CaO–TiO 2 mixture

Microstructure of the CaO–TiO 2 mixture ground under dry atmospheric condition using a planetary ball mill was investigated by transmission electron microscopy–energy dispersive X-ray spectroscopy (TEM-EDX) and high resolution transmission electron microscopy (HR-TEM) with selected area electron diffraction (SAED) analysis. According to the TEM observation, the mixtures ground for about 2 h or more consist of many fine particles of about 20 nm. The CaTiO 3 microcrystals are formed in the mixture ground for about 2 h or more. One of the lattice planes, {121} is clearly observed in the HR-TEM micrograph of the 5-h ground mixture, while the lattice image is partly detected in the mixture ground for about 2 h or less. The grains grow in size in the prolonged grinding, and their sizes reach about 20 nm at 5 h grinding by the TEM observation. The size of microcrystals becomes larger with increasing grinding time.

Effect of Particle Size of Powders Ground by Ball Milling on Densification of Cordierite Ceramics.

Mixtures of calcined kaolin, calcined talc and alumina were ground to submicron particle size by ball milling, and the effect of particle size of the ground mixtures on the densification behavior of a cordierite sintered body was studied. As the particle size of the ground mixtures became smaller, the raw material powders were mixed more uniformly and the formation temperature of α-cordierite became lower. Dense and pore-free sintered bodies were obtained by firing ground mixtures with particle size smaller than 0.39μm at temperatures as low as 1200°C. Cordierite sintered bodies prepared from mixtures with particle size 0.39μm or smaller by grinding natural raw materials had bending strengths ranging from 140-160 MPa, and these values were larger than that of cordierite glass-ceramics reported by Hayashi et al. The thermal expansion coefficients of dense, high-strength cordierite bodies increased, because anisotropic thermal expansion could not lower the amount of thermal expansion in the pore-free body.

Effect of Sucrose Esters of Fatty Acids on In Vitro Release and Physico-Chemical Properties of Halopredone Acetate Ground Mixture with Tamarind Gum

Effect of Sucrose Esters of Fatty Acids on <i>In Vitro</i> Release and Physico-Chemical Properties of Halopredone Acetate Ground Mixture with Tamarind Gum

コーディエライトセラミックスの生成反応過程と物理特性に及ぼすコランダム（α‐Ａｌ２Ｏ３）およびギブサイト（Ａｌ（ＯＨ）３）の影響

We studied the effect of a corundum and gibbsite on the reaction process andphysical properties of cordierite ceramics. The results were as follows:(1) In the fired bodies obtained from the kaolin-talc-gibbsite mixture, gibbsite attributed to the cordierite formation without rearrangement into corundum in the firing process.(2) In the case of small particle size of ground mixture, apparent porosity of bodies fired at 1200°C were 0% in both case of kaolin-talc-corundum mixture and kaolin-talc-gibbsite mixture.(3) The bending strength and thermal expansion coefficient of bodies fired at1300°C obtained from both mixtures increased with decrease in particle size ofground mixtures. The optimum particle size of kaolin-talc-gibbsite mixture wasabout 0.4μm, because over grinding mixture caused a decrease in cordieritecontent of body fired at 1300°C.

Variety of foods and flavors affects selection of foraging location by sheep

Our objective was to determine if variety of dietary flavors and ingredients affected selection of foraging locations by sheep. We hypothesized lambs would forage in locations that offered a variety of flavors and/or nutritional characteristics and on foods that differed from their basal diet. We tested this hypothesis in four trials. During Trial 1, lambs were fed a basal ration of alfalfa pellets (2.41 Mcal/kg DE, 18% CP), and then offered a test diet that was a ground mixture of 58% barley, 20% alfalfa, 17% grape pomace, 4% soybean meal, and 1% minerals (2.69 Mcal/kg DE and 14.7% CP). The test diet was offered at two different locations, one that provided the diet with a variety of added flavors (apple, anise, unadulterated) and the other that provided the diet in only the most preferred flavor (apple or anise). Procedures were the same during Trial 2, except the basal ration and the test diet were the same and different flavors were offered at the variety (apple, anise, fresh forage) and monotony (fresh forage) locations. During Trial 1, when the test diet differed from the basal diet, variety of flavors did not affect foraging location ( P>0.05), but during Trial 2, when the basal diet was identical to the test diet, lambs preferred to forage where there was a variety of flavors ( P<0.05). During Trials 3 and 4, the test diet was offered in different flavors along with alfalfa pellets (Trial 3) or ground alfalfa (Trial 4) at the variety location, whereas the test diet was offered in the preferred flavor at the monotony location. During Trial 3, lambs spent more time at the variety location, and they ate more pellets than the ground test diet, even though the test diet had higher concentration of energy ( P<0.05), evidently because macro-nutrients consumed/unit time was greater for pellets than for the ground test diet. In Trial 4, lambs spent more time and ate more food where there was variety of foods and flavors ( P<0.05), apparently because alfalfa and the test diet were complementary in flavor and nutrition. Collectively, our results suggest lambs selected foraging locations based primarily on nutritional factors, but when nutrient content was constant, variety of flavors was important.

Enhanced dissolution of furosemide by coprecipitating or cogrinding with crospovidone

To increase the dissolution rate of furosemide, cogrinding or coprecipitating of furosemide with crospovidone was carried out. The 1:2 (w/w) ground mixture of furosemide with crospovidone was prepared by cogrinding in a ceramic ball mill and the coprecipitate was prepared by the solvent method using methanol. The dissolution test was carried at 37±0.5°C and 150 rpm in simulated gastric fluids (pH 1.2). The dissolution rate of furosemide was rapid and markedly enhanced by cogrinding or coprecipitating with crospovidone. The X-ray diffraction, IR, DTA and TGA studies showed the physicochemical modifications of the furosemide from the ground mixture or the coprecipitate. Furosemide alone or furosemide contained within a physical mixture was crystalline in nature, whereas furosemide in the ground mixture or the coprecipitate was not crystalline even when preserved at room temperature for 1 year. An interaction, in the ground mixture or in the coprecipitate, such as an association between the functional groups of furosemide and crospovidone may have occurred at the molecular level, changed the thermal property and increased the dissolution of furosemide. The cogrinding or coprecipitating techniques with crospovidone provide a promising way to increase the dissolution rate of poorly soluble drugs.

Pb diffusion in clinopyroxene

Chemical diffusion of Pb under anhydrous, pO 2-buffered conditions has been measured in natural clinopyroxenes of two different compositions: one a near-end-member diopside and the other of more iron-rich composition (∼40% diopside component). The sources of diffusant were fused and finely ground mixtures of PbS powder and ground pyroxene. Experiments were run in sealed silica glass capsules with a solid buffer (to buffer at QFM). Rutherford backscattering spectrometry (RBS) was used to measure diffusion profiles. The following Arrhenius parameters were obtained for diffusion normal to (110) over the temperature range 800–1100°C under QFM-buffered conditions: D=4.03×10 2exp(−544±40 kJ mol −1/ RT) m 2 s −1 (for Di 95) D=2.20×10 −4exp(−387±31 kJ mol −1/ RT) m 2 s −1 (for Di 40). Diffusion in the more iron-rich clinopyroxene is faster and activation energy for diffusion lower than that for the near-end-member diopside. Little dependence of Pb diffusion on crystallographic orientation was noted in diopside. Diffusion of Pb is comparable to that of Sr in natural diopside, but faster than many other species in clinopyroxenes. The activation energy for Pb diffusion in diopside is relatively high and Pb diffusivities are fairly slow when compared with the extant diffusion data for other minerals. It follows as consequence of these relatively slow diffusivities that Pb closure temperatures are higher in diopside than for most other minerals, with the exception of a few phases such as zircon and garnet. The faster diffusivities that characterize Fe-rich clinopyroxenes will lead to somewhat depressed closure temperatures, but clinopyroxenes in general should be fairly retentive of Pb isotopic information when subjected to all but the most extreme thermal events.

Effect of Guest Species on Inclusion Compound Formation of Deoxycholic Acid by Co-Grinding

Abstract Deoxycholic acid (DCA) was ground with a guest compound by using a vibrational mill. Powder X-ray diffraction, differential scanning calorimetry, and fluorescence spectroscopic data indicated the formation of the inclusion complex in the ground mixture of DCA–phenanthrene and DCA–naphthalene systems. The DCA–naphthalene ground mixture was found to have higher crystallinity than the DCA–phenanthrene ground mixture, and this was assumed to relate to the difference in the crystallization temperature of the inclusion complex. When low-temperature grinding was performed for DCA and other aromatic hydrocarbons along with naphthalene and phenanthrene, all the ground mixtures were obtained in amorphous state. Crystallization of inclusion compounds from the amorphous ground mixtures was observed to occur at a higher temperature as the stoichiometric ratio (DCA/guest) of the compound increased. With regard to the formation of crystalline complex between DCA and a guest, such as naphthalene, by grinding at room temperature, a two-step mechanism was proposed: i.e., (i) amorphization of both DCA and guest crystals, and (ii) crystallization of the inclusion complex induced above a certain temperature.

Formation of CaTiO3 by grinding from mixtures of CaO or Ca(OH)2 with anatase or rutile at room temperature

Room temperature grinding by a planetary ball mill has been applied to four kinds of mixtures prepared from CaO or Ca(OH) 2 and anatase or rutile (TiO 2 ). Crystalline CaTiO ? can be mechanochemically synthesized by grinding the mixture of CaO with both forms of TiO 2 but is difficult to obtain from the mixtures of Ca(OH) 2 and TiO 2 . These observations are in contrast to the result of Avvakumov et al. [E.G. Avvakumov, E.T. Devyatkina, N.V. Kosova. Mechanochemical reacions of hydrated oxides. J. Solid State Chem. 113 (1994) 379–383] and are in agreement with the thermodynamic data. The reactivity of CaO or Ca(OH) 2 with anatase is slightly higher than is the case with rutile. Heating of the ground mixtures at about 900–1200 K is found to be effective for producing crystalline CaTiO ? .

DSC Study of Crystallinity Changes of Naproxen in Ground Mixtures with Linear Maltooligomers

Differential scanning calorimetry was applied for an analysis of the cogrinding-induced crystallinity changes of naproxen in binary mixtures with linear maltooligomers. Factors found to play a role in the amorphization process were the mixture composition, the duration of mechanical treatment and the degree of polymerization of the carrier. Maltopentaose was about as active as amorphous hydroxypropyl α- and β-cyclodextrin MS 0.6, while maltotetraose displayed practically the same amorphizing capacity as those of native α- and β-cyclodextrin. The melting peak temperature of naproxen was substantially unaltered by cogrinding with maltooligomers, whereas it was considerably lower in coground mixtures with cyclodextrin derivatives. This might be due to the formation of a true inclusion complex in the solid state.

Mechanochemical Adsorption of Phenol by Tot Swelling Clay Minerals

The mechanochemical adsorption of phenol by laponite, saponite, montmorillonite, beidellite and vermiculite was studied by IR and X-ray spectroscopy. Mixtures containing phenol and clay in the ratio of 6:10 were manually ground by a mortar and pestle for 1,3,5 and 10 min and the ground mixtures were investigated. Depending on the basicity of the clay mineral and the time of grinding, two different associations between interlay er cations, water and phenol were identified. In these associations phenol can act either as a proton acceptor or donor (Configurations I and II, respectively). The phenol is more acidic than water and in most cases phenol acts as a proton donor. With montmorillonite and beidellite phenol acts as a proton acceptor. In this association the aromatic ring forms π bonds with atoms of the oxygen planes of the tetrahedral sheets which donate electrons to the anti-bonding π orbitals of the phenol.

Reduction enhancement of Fe2O3 in physical mixtures with Pt/mordenite via Pt migration or ‘hydrogen spillover’

Mixing Fe2O3 with Pt/NaMor of similar grain size, followed by grinding in a mortar and calcination in O2, leads to a remarkable enhancement of the reducibility of the Fe2O3 with hydrogen. The TPR profile of such mixtures is virtually identical with that of Fe2O3 onto which Pt was deposited chemically. It is concluded that in the ground and calcined mixtures Pt migration from the zeolite to the iron oxide is crucial. Upon varying the amount of deposited Pt in Pt/Fe2O3 between 0.001% and 1%, TPR profiles are obtained showing two discrete peaks characterizing a Pt promoted and an unpromoted reduction of Fe2O3 respectively. No Pt migration occurs in mixtures of prereduced Pt/NaMor with Fe2O3; this shows that surface migration of P clusters is negligible, but transport of PtO2 either through the gas phase or via the surface is likely. Pt migration is also detectable at room temperature in mixtures stored for weeks in a moist atmosphere; in this case the data suggest surface migration of hydrated Pt2+ ions; the TPR profiles are distinctly different from those of the mixtures calcined in O2. TPR also permits discrimination between the promotion of oxide reduction by migrating Pt and ‘true’ hydrogen spillover. The latter phenomenon requires transport of H atoms via protons and electrons and is realized with powder mixtures containing a semiconducting oxide, such as TiO2. Its TPR signature is a broad peak located between those for unpromoted and Pt promoted reduction. Physical mixtures of Fe2O3 and Pt/NaMor catalyze the reduction of acetic acid vapor to acetaldehyde via a Mars–van Krevelen mechanism. In this case Pt migration helps to regenerate oxygen vacancies in the Fe3O4 surface, whereas direct contact of CH3CO2H vapor with Pt results in the formation of methane and higher hydrocarbons. The promoting effect of Pt is not observed after prereduction of Pt/NaMor, because P does not migrate effectively under the conditions used.

Mechanochemical Synthesis of Tricalcium Aluminum Hydrate from Calcium Hydroxide-Boehmite Mixtures by Room Temperature Grinding.

Tricalcium aluminum hydrate (3CaO·Al2O3·6H2O：C3AH6) is synthesized mechanochemically from mixtures composed of calcium hydroxide (Ca(OH)2) and pseudo-boehmite (γ-AlO(OH)) powders by room temperature grinding using a planetary ball mill. Use of the boehmite sample with inferior crystallinity is more favorable for the mechanochemical synthesis rather than that with well crystalline one. The time required to form C3AH6 from the Ca(OH)2-γ-AlO(OH) mixture is much longer than that from the Ca(OH)2-gibbsite (Al(OH)3) one. Adsorbed water from air during grinding plays a significant role in the formation of C3AH6 from the former mixture. After water addition to Ca(OH)2-γ-AlO(OH) mixtures ground for various times, excess hydrated calcium aluminates such as C2AH8, C3AH8-12 and C2A0.5H6.5 are formed in the starting and the short time ground mixtures, while a few amount of these compounds is formed in these hydrated mixtures after prolonged grinding. Formation of these excess hydrated compounds, which belong to layered structural materials, is enhanced in the presence of free Ca, Al compounds and water.

Non-thermal process for extracting rare earths from bastnaesite by means of mechanochemical treatment

A novel process for extracting rare earths such as Ce, La contained in bastnaesite mineral (ReCO 33F, Re = rare earths) has been developed in this work. This process is composed of three steps. The first step is milling of the mixture of bastnaesite and NaOH powders, forming mechanochemically Re(OH) 3 and Na compounds. The second step is washing of the ground mixture with water, removing the soluble Na compounds. The third step is leaching of the washed powder with HCl or H 2SO 4 solutions at room temperature, extracting the rare earths. The extractive yield of rare earths is improved with an increase in milling time. Furthermore, HCl solution is superior to H 2SO 4 as a leaching medium. In the present work, more than 90% of the rare earths in the bastnaesite sample was extracted by dilute HCl solution from the mixture milled for 120 min.

Mechanochemical synthesis of tobermorite by wet grinding in a planetary ball mill

Wet grinding of mixtures of calcium hydroxide and silica gel with different molar ratios (Ca/Si) ranging from 0.5 to 3.0 was conducted in a planetary ball mill. Three hours of wet grinding enables us to synthesize tobermorite mechanochemically when the molar ratio of the mixture is controlled at about unity, while calcium silicate hydrate-(B) (CSH (B)) is mechanochemically synthesized within about 1.5 h. The presence of excess water, by about four times the mixture's weight in the mill, leads effectively to the mechanochemical synthesis of tobermorite by grinding. Tobermorite synthesized mechanochemically shows similar thermal behavior to that synthesized hydrothermally. However, crystallinity of the former compound is slightly inferior to that latter one. The ground mixture containing tobermorite is thermally decomposed at about 1120 K, forming wollastonite via an amorphous phase, while the mixture with synthesized CSH (B) is decomposed at about 1100 K, forming ϵ-wollastonite via a transitional crystalline phase.

X-ray study of the thermal intercalation of alkali halides into kaolinite

Intercalation complexes of kaolinite with a series of alkali halides (NaCl (trace amounts), KCl, RbCl, CsCl, NaBr, KBr, CsBr, Kl, Rbl and Csl) were obtained by a thermal solid state reaction between the kaolinite-dimethylsulfoxide intercalation complex and the appropriate alkali halide. The ground mixtures (1∶1 weight ratio) were pressed into disks that were gradually heated up to 250 °C for different times. X-ray diffractograms of the disks were recorded after each thermal treatment. At the end of the thermal treatment the disks were ground and basal spacings of the powders obtained. As a result of thermal treatment, alkali halide ions diffuse into the interlayers, replacing the intercalated dimethylsulfoxide molecules. Such a replacement may take place only if the thermal diffusion of the penetrating species is faster than the evolution of the intercalated organic molecule. With increasing temperature the intercalated salt diffused outside the interlayer space or underwent a thermal hydrolysis which resulted in the evolution of hydrogen halides from the interlayer space. Consequently, the amounts of intercalation complexes decreased at elevated temperatures.

Impact grinding of thermoplastics: A size distribution function model

AbstractSeparation of poly(ethylene terephthalate) (PET) from poly(vinyl chloride) (PVC) is an important problem when recycling bottles and other consumer products. Previous work has identified a processing window for the selective grinding of a mixture of PET and PVC. Impact grinding for conditions within the processing window will ensure that one polymer fails in the ductile mode and the other fails in the brittle mode, giving differences in sizes and shapes between the ground polymers. The ground mixture can be separated by physical means such as screening. This study develops size distribution models for the impact grinding of PET and PVC chips, an important tool for the operation and control of a selective grinding process. The distribution coefficients can be related to grinding conditions, and to the failure mechanism of the polymer.

Pharmaceutical Properties of Nifedipine from a Ground Mixture with Nifedipine, Casein, Magnesium Silicate and Cellulose Acetate Phthalate.

The dissolution step of practically insoluble drugs plays an important role in drug absorption. In this paper, the pharmaceutical properties of a ground mixture of nifedipine are described. A ground mixture of nifedipine was prepared by grinding with casein, magnesium silicate, and cellulose acetate phthalate in a vibrational ball mill. The X-ray powder diffraction patterns and differential scanning calorimetry data thereafter suggested that nifedipine was present in its amorphous form in the ground mixture. The wettability of the ground mixture was better than that of the physical mixture. The solubility of amorphous nifedipine in water was also better than that in crystalline. Both the dissolution rate and the bioavailability of amorphous nifedipine in the ground mixture were significantly greater than those of the physical mixture. The above results thus suggest that a mixture grinding method not only improves the solubility of nifedipine and the dissolution profile of its preparation but also enhances its bioavailability after oral administration.

Complex Formation between Deoxycholic Acid and Menadione by Grinding and Sealed Heating Methods.

Complex formation between deoxycholic acid (DCA) and menadione (MND) by grinding and sealed heating was investigated. The complex between DCA and MND was prepared by coprecipitation and showed a stoichiometry of 2 : 1 (DCA : MND). The IR spectrum of the complex suggested that MND molecules were located in the channel formed by DCA molecules. The 10 min ground mixture of DCA-MND gave the same X-ray diffraction pattern as the DCA-MND coprecipitate. Differential scanning calorimetry (DSC) and IR spectroscopy also demonstrated the identical results between the ground mixture and the complex, confirming the complex formaiton between DCA and MND by grinding. The DSC data suggested that the complex formation was expected during heating process of the DCA-MND physical mixture. The sealed heated samples were prepared and compared with the complex prepared by coprecipitation. After heating in a sealed ampoule at 110°C for 10 min or at 80°C for 24h, samples demonstrated the same X-ray diffraction patterns, DSC curves and IR spectra as the complex. These results indicated that the complex formation took place between DCA and MND by sealed heating as well as by grinding.

Preparation of Magnesium Hydroxide from Magnesite by means of Mechanochemical Treatment and its Reactivity.

Mechanochemical process for producing Mg (OH) 2 from magnesite (MgCO3) without heat treatment has been developed. This process is composed of two steps: The first step is to produce Mg (OH) 2 and Na2CO3 mechanochemically by dry grinding the mixture of magnesite and solid NaOH powders in a mill. The reaction between the two starting samples proceeds as the grinding progresses. The second step is to separate Na2CO3 from the insoluble products in the ground mixture by washing with water. Reactivity of the insoluble products against H2SO4 solution is improved with increasing the grinding time, and levels off in the prolonged grinding. The reactivity of the insoluble products prepared from the mixtures ground for 0 minutes or more is much higher than that of magnesite powder. The separated Na2CO3 can be reused for appropriate purposes