A Study of the Properties of Compacts from Silicified Microcrystalline Celluloses

ABSTRACT

The paper deals with a study of tensile strength and disintegration time of compacts made from silicified microcrystalline celluloses, Prosolv SMCC 90, and Prosolv HD 90, in dependence on compression force, addition of two types of lubricants, and two active ingredients. The lubricants were magnesium stearate and sodium stearyl fumarate in a concentration of 0.5%, the active ingredients being ascorbic acid and acetylsalicylic acid in a concentration of 50%.

Prosolv SMCC 90 proved to be better compatible than Prosolv HD 90; the compacts were of higher strength, which was markedly increased with increasing compression force. Prosolv HD 90 was more sensitive to additions of lubricants, and a greater decrease in strength was recorded due to the influence of sodium stearyl fumarate. The effect of lubricants on the strength of compacts in the presence of active ingredients was not identical. The disintegration time of compacts from Prosolv HD 90 without as well as with lubricants was shorter than from Prosolv SMCC 90 and was increasing with increasing compression force. Disintegration time was increased with added lubricants, and it was markedly shortened by addition of active ingredients. Compacts containing ascorbic acid possessed a shorter disintegration time than those containing acetylsalicylic acid, and it was not markedly influenced by the presence of lubricants.     

A study of the compaction process and the properties of tablets made of a new co-processed starch excipient

This article deals with the study of the energetic relationships during compaction and the properties of tablets produced from a co-processed excipient based on starch and called StarCap1500^®. This article compares it with the substance Starch1500^®. The study also includes the mixtures of StarCap 1500^® and the granulated directly compressible lactose Pharmatose DCL^®15. The tablet properties tested included tensile strength and disintegration time, examined in dependence on compression force, and also a 0.4% addition of magnesium stearate. The results show a better compressibility of StarCap 1500 in comparison with Starch 1500 and a lower elastic component of energy. The tablets were stronger and disintegrated more rapidly, but the substance possessed a higher sensitivity to an addition of a lubricant than Starch 1500. Increasing portions of StarCap 1500 in the mixtures with Pharmatose DCL 15 increased the tensile strength of tablets, disintegration period as well as the sensitivity to an addition of a lubricant. From the energetic viewpoint, energy for friction was decreasing, while the energy accumulated by the tablet during compaction and the elastic component of energy were increased.     

A screening technique to study the mechanical strength of gelatin formulations

A semiquantitative method for measuring the mechanical strength of gelatin ribbons was demonstrated using a universal tensile testing machine (Instron, model 1122). Molten gelatin formulations comprised of acid-bone gelatin, limed-hide gelatin, or their combinations were made, pored as gelatin films, and aged at 50% relative humidity (RH). Viscoelastic properties (mechanical strength) of five gelatin formulations were evaluated by determining elastic modulus, tensile strength, and ratio of tensile strength to elastic modulus of gelatin ribbons. This study demonstrated that a 3:1 ratio of acid-bone to limed-hide gelatin combination showed better viscoelastic properties than the other formulations studied.     

Influence of the impact sintering temperature on the structure and properties of samples from the different iron powders

The studies of the consolidation, structure and mechanical properties of samples from two types of iron powder are carried out. The coarse and less pure PZH3M2 as well as fine and purer DIAFE5000 powders were used. The samples are obtained by means of impact sintering method in the temperatures range of 500–1100 °C. The impact energy was 1200 J/cm³, and the initial deformation velocity - 6.5 m/s. Samples are obtained in the form of disks with a diameter of 25–27 mm and 9–10 mm high. For carrying out different mechanical tests the bars were cut out from disks. The tensile, compression, three-point bend of notched samples tests were carried out, as well as the Brinell hardness was measured after the corresponding processing of the bars. The characteristics of strength and plasticity of samples depending on the impact sintering temperature are determined. The polished surface of different samples and the fracture surface are investigated. It is established that the high density of samples is reached at a temperature of 600 and 700 °C respectively for fine and coarse powders. The samples obtained at these impact sintering temperatures possess rather low electrical resistivity, high strength, hardness, but the lowered plasticity. Namely, the samples from the PZH3M2 and DIAFE5000 powders sintered at the temperature of 700 °C have respectively: ultimate tensile strength - 406 and 336 MPa, yield stress - 353 and 190 MPa, contraction ratio - 26 and 78%, limit stress (at the fracture) - 501 and 933 MPa, the maximum crack tip stress – 738 and 876 MPa, the fracture energy at a bend of the notched samples - 4.8 and 51.2 J/cm³ and also Brinell hardness - 1467 and 847 MPa. The increase of the samples impact sintering temperature leads to grain growth, decrease of the samples strength and increase of their plasticity. At the same time the structure of samples from the DIAFE5000 powder is more fine-grained than at samples from the PZH3M2 powder.     

Influence of various acids on the physico-mechanical properties of pozzolanic cement mortars

Acidic attack represents a topic of increasing significance, owing to the spread of damages of concrete structures in both urban and industrial areas. Cement type is an important factor affecting performance of cement based materials in an aggressive environment. The goal of this study was to compare the acid resistance of a pozzolanic cement (CEM IV-A/32·5) with Portland cement (CEM I 32·5) that was made from the same clinker. For this purpose, 50mm mortar cubes were prepared with two different kinds of cement according to TS EN 196-1. After 28 days of hardening, the samples were immersed into four different concentrations of hydrochloric, nitric and sulfuric acid solutions for a period of 120 days. The changes in weight loss and compressive strength values for each acid solution within the test period were recorded. The acid resistance of mortars made from Portland cement was better than the pozzolanic cement incorporated samples after 120 days of acid attack.     

A study on the mechanical properties of cryorolled Al–Mg–Si alloy

The mechanical properties of a precipitation hardenable Al–Mg–Si alloy subjected to cryorolling and ageing treatments are reported in this present work. The severe strain induced during cryorolling of Al–Mg–Si alloys in the solid solutionised state produces ultrafine microstructures with improved mechanical properties such as strength and hardness. The improved strength and hardness of cryorolled alloys are due to the grain size effect and higher dislocation density. The ageing treatment of cryorolled Al–Mg–Si alloys has improved its strength and ductility significantly due to the precipitation hardening and grain coarsening mechanisms, respectively. The reduction in dimple size of cryorolled Al–Mg–Si alloy upon failure confirms the grain refinement and strain hardening mechanism operating in the severely deformed samples.     

A proposed methodology for the global study of the mechanical properties of cold asphalt mixtures

Despite having been used for decades, the structural performance of emulsion-treated materials has still not been investigated as intensely as in the case of hot-mix asphalt (HMA). Proof of this is the lack of evolution of specific technical tests and standards. Due to this, many studies with cold asphalt mixtures (CAM) are carried out based on HMA specifications. Throughout the present paper, a new methodology is proposed in order to study different mechanical properties of CAM, such as unconfined compression strength (UCS), indirect tensile strength (ITS) and indirect tensile stiffness modulus (ITSM) not only in an independent way but also by giving a global approach. The consistency and applicability of the method is discussed and from its application to a practical case study with two very different CAM, new conclusions about their performance are laid down.     

A study of the effect of filler metal thickness on tensile strength for a stainless steel plate-fin structure by experiment and finite element method

This paper presents a study of the effect of filler metal thickness on tensile strength for a stainless steel plate-fin structure by finite element method and experiment. The results show that the filler metal thickness has a great effect on tensile strength. The tensile strength is increased with the filler metal thickness increase, then it keeps stable when the filler metal thickness is 105–140 μm. But it decreases rapidly when the filler metal thickness is larger than 140 μm. The fracture location is shown at the end of vertical fin when the filler metal thickness is 105–140 μm. Specimens with filler metal thickness smaller or larger than 105–140 μm rupture in the brazed filler metal. The optimal filler metal thickness is 105 μm, using which can get higher strength for 304 stainless steel plate-fin structures.     

用吸附处理工艺去除饮用水中阴离子表面活性物质的实验研究

采用活性炭、沸石和硅藻土三种常用吸附剂,通过静态实验和动态实验对饮用水中低浓度阴离子表面活性物质(LAS)的去除进行了考察.静态实验结果表明,用吸附法可有效地去除LAS,并且在通常条件下受温度、pH影响不显著,但在有机物如腐殖酸浓度较高的情况下LAS的吸附明显受到抑制.动态实验比较了不同LAS浓度、不同吸附剂对流出曲线的影响,并求出LAS的孔扩散系数和液膜扩散系数.考察LAS和腐殖酸双组分溶液穿透时间及饱和分数的结果表明,腐殖酸为控制化合物,因此实际应用中只需要考虑腐殖酸的去除即可满足LAS的去除要求.     

Influence of key cement chemical parameters on the properties of metakaolin blended cements

The use of metakaolin (MK) as a mineral admixture for cement and concrete is a well-documented practice. The properties of cement pastes and mortars containing MK have been investigated as a function of key cement chemical parameters recognized as potential activators of the MK. Rheological behavior, initial setting time and compressive strength development have been compared by varying the total sulfate content, the nature of the added calcium sulfate and the free lime content (in the form of portlandite) in the cement. The results obtained indicate that it exists a compromise for the ratio performance/consistency in term of sulfate content and nature. Concurrently, a small addition of portlandite improves the consistency of the properties investigated.     

A comparative study on the raft chemical properties of various alginate antacid raft-forming products

Objective: Research to measure the chemical characterization of alginate rafts for good raft performance and ascertain how formulation can affect chemical parameters.

Significance: A selection of alginate formulations was investigated all claiming to be proficient raft formers with significance between products established and ranked.

Methods: Procedures were selected which demonstrated the chemical characterization allowing rafts to effectively impede the reflux into the esophagus or in severe cases to be refluxed preferentially into the esophagus and exert a demulcent effect, with focus of current research on methods which complement previous studies centered on physical properties. The alginate content was analyzed by a newly developed HPLC method. Methods were used to determine the neutralization profile and the acid neutralization within the raft determined along with how raft structure affects neutralization.

Results: Alginate content of Gaviscon Double Action (GDA) within the raft was significantly superior (p?Conclusion: Alginate formulations require three chemical reactions to take place simultaneously: transformation to alginic acid, sodium carbonate reacting to form carbon dioxide, calcium releasing free calcium ions to bind with alginic acid providing strength to raft formation. GDA was significantly superior (p?<.0001) to all other comparators.     

有序和无序FeAl的磁性能研究

有序-无序转变对FeAl金属间化合物磁性能的影响应当引起重视。许多实验和理论研究表明完全有序的FeAl是无磁的。但是,可以通过非平衡技术使FeAl无序化,如快速凝固、冷加工、溅射、共蒸发和机械合金化。本文利用固体与分子经验电子理论（EET）和Jaccarino—Walker模型对此进行了研究,结果表明,完全无序的FeAl是铁磁性的,每个Fe原子的平均原子磁矩是1．41μB。     

自增强高性能聚合物的成型工艺同力学性能间相关性研究——5.一种从实验上来测定取向聚乙烯纤维理论强度的新方法

本文提出了一种从实验上来测定取向聚乙烯纤维理论强度的新方法。它基于自增强高聚物恒定应力下持久强度动力学模型理论,采用自增强高聚物非晶区(或微区)中伸直应力集中链系数作为自变量来建立微区中伸直应力集中链(TautTie Molecule和/或Trapped Entanglement Chain)的断链动力学方程,经积分和化简后,得到了自增强高聚物的抗张强度同其起始结构、成型工艺、测试条件和断裂时间等的一般关系式。当把牵伸时间t_D远远大于松弛时间τ_3和起始分子量趋近无穷大时,结合光子强度理论后就得到了超拉伸高取向高聚物的抗张强度同理论强度、微区中应力集中伸直链(TTM和/或TEC)的重量分数(X_(e3))和热涨落等间的定量关系,并提出了一种从实验上来测定高取向纤维理论强度的新方法。用该法测定了超高分子量聚乙烯(UHMWPE)纤维的理论强度,其结果同理论计算值很好符合。     

自增强高性能聚合物的成型工艺同力学性能间相关性研究——5.一种从实验上来测定取向聚乙烯纤维理论强度的新方法

本文提出了一种从实验上来测定取向聚乙烯纤维理论强度的新方法。它基于自增强高聚物恒定应力下持久强度动力学模型理论,采用自增强高聚物非晶区(或微区)中伸直应力集中链系数作为自变量来建立微区中伸直应力集中链(TautTie Molecule和/或Trapped Entanglement Chain)的断链动力学方程,经积分和化简后,得到了自增强高聚物的抗张强度同其起始结构、成型工艺、测试条件和断裂时间等的一般关系式。当把牵伸时间t_D远远大于松弛时间τ₃和起始分子量趋近无穷大时,结合光子强度理论后就得到了超拉伸高取向高聚物的抗张强度同理论强度、微区中应力集中伸直链(TTM和/或TEC)的重量分数(X_e3)和热涨落等间的定量关系,并提出了一种从实验上来测定高取向纤维理论强度的新方法。用该法测定了超高分子量聚乙烯(UHMWPE)纤维的理论强度,其结果同理论计算值很好符合。      

A study on the influence of clamping on welding distortion

This paper presents numerical case studies on the influence of clamping on welding distortion. For the case studies a 1 mm DP600 overlap joint and a 6 mm S355 T-joint have been selected, and reference simulations have been performed. The results have been compared to experiments in a previous paper and show a good agreement. The influence of the clamping time, the release time and the influence of clamp preheating has been investigated for both geometries. Here, the effect of the clamping on buckling distortion as well as bending and angular distortion has been studied. It is shown that the final residual stresses and distortions depend strongly on the clamping conditions. Adaptive clamping may be helpful as an in-line technique for welding distortion mitigation by forcing the material to deform plastically.     

Comparative study on the structural and catalytic properties of mesoporous hexagonal silica anchored with H3PW12O40: Green synthesis of benzoic acid from benzaldehyde

Mesoporous silica anchored with 25 wt.% 12-tungstophosphoric acid (H₃PW₁₂O₄₀, HPW) were comparatively characterized on their structures and catalytic activities for benzaldehyde oxidation with H₂O₂. The results revealed that the mesoporous materials retained the typical hexagonal mesopores for the supports of HPW. It was found that HPW exhibited higher dispersion within MCM-41 than those within SBA-15 and other mesoporous molecular sieves. Moreover, the as-prepared materials were found to be the efficient catalysts for the green synthesis of benzoic acid. In particular, HPW/MCM-41 exhibited the best catalytic properties due to its suitable textural and structural characteristics.     

A study of elastic aftereffect in injection casting of thermoplastic feedstocks based on SiC,AlN, WC powders and its influence on mechanical properties of the workpiece material

The paper addresses the changes in dimensions of products prepared from thermoplastic feedstocks based on SiC, AlN, WC powders and paraffin by injection molding. The authors study the influence of the process pressure, temperature, and powder particle size on the elastic aftereffect in the product material as well as the influence of the injection casting variables (pressure and temperature) on the ultimate bending strength of the product material.