Binders based on aqueous dispersions of polymers for plastic shaping of ceramic products

Some special features of the deformation behavior of plastic corundum mixtures and semifinished products with temporary technological binders based on aqueous dispersions of polyvinyl acetate and polymethyl acrylate are considered. As compared to conventional binders, the new binders widen the range of the plastic state of the mixtures with preservation of a high level of molding properties and make it possible to increase the strength of molded preforms. It is shown that the binders are applicable for shaping articles from narrow-fractionated powders.     

Engineering Lignocellulose Fibers with Higher Thermal Stability through Natural Fiber Welding

This study reveals how natural fiber welding (NFW) can be used to engineer biopolymer materials with improved thermal stability. First, it is shown how NFW without binders improves lignocellulose yarn thermal stability by ≈17 °C, primarily by condensing microfibril structure. Next, silanized‐cellulose nanofibrils (Si‐CNFs) are developed as NFW binders; this silanization process alters CNF physical and thermal properties. During pyrolysis, Si_x O_y networks form, which delay CNF decomposition (up to 37 °C), slow cellulose mass loss rates (up to 89%), and can enhance char yield more than twofold. When used as NFW binders, Si‐CNFs increase lignocellulose yarn thermal stability (up to 17 °C) proportional to siloxane amount, and can reduce cellulose mass loss rates (≈25% compared to welding without binder). These exciting results highlight the potential of NFW as a green‐engineering process to transform natural fibers into more thermally stable, biocomposite textile yarns.     

Selection of the Binder Composition for Abrasive Electrocorundum Instruments

The properties of ceramic binders used in the production of electrocorundum abrasive instruments are discussed. The methods for studying the properties of ceramic binders are analyzed, including the methods making it possible to study the process of sintering of the binder components and the electrocorundum grains and the formation of the binder structure and the contact zone between the binder and the electrocorundum.     

高掺量粉煤灰水泥胶凝材料的水化性能研究

用ＴＭＳ－ＧＣ,ＸＲＤ,ＤＴＡ,ＳＥＭ等方法研究了高掺量粉灰水泥胶凝材料的水化性能;分析了粉煤灰掺量、激发剂等对高掺量粉煤灰水泥胶凝材料水化性能的影响,并与硅酸盐水泥的水化性能进行了对比。结果认为：高掺量粉煤灰水泥的水化速度低于不掺灰的硅酸水泥的水化速度,但后期增长较快;激发剂能加快高掺量粉煤灰水泥的水化速度。     

Mechanical properties of plastic‐bonded explosive binder materials as a function of strain‐rate and temperature

Compression measurements were conducted on three explosive formulation binders, extruded Estane, plasticized Estane, and plasticized hydroxyl‐terminated polybutadiene, as a function of temperature and strain rate. The mechanical response of the Estane was found to exhibit the strongest dependency on strain rate and temperature and higher flow strength for similar test conditions of the three materials tested. Plasticized Estane was less sensitively dependent on strain rate and temperature, followed by the plasticized HTPB. The visco‐elastic recovery of all three binders is seen to dominate the mechanical behavior at temperatures above the glass transition temperature (T_g). There is a pronounced shift in the apparent T_g to higher temperatures as the strain rate is increased. Two distinct behaviors are observed in the binders below the T_g. At low strain rates, the binders exhibit a yield behavior, followed by a drop in the flow stress, which may or may not recover. At high strain rates, the load drop does not occur and the flow stresses either gradually increase, as in plasticized HTPB, or it levels out as seen in the Estane‐based binders. POLYM. ENG. SCI., 46:812–819, 2006. © 2006 Society of Plastics Engineers     

非稳定结构矿物质的接触硬化性能

阐述了新颖的接触硬化工艺方法制备人造石的独特优点及其基本原理,用动态水热合成方法制成了性能优异的以水化硅酸钙为主的接触硬化胶凝材料,研究了它们的强度与抗水性能,找到了耐压制过程中能降低模壁与物料摩擦作用的润滑剂,制成了立即抗压强度达８４ＭＰａ的高强度接触硬化石材,论述了接触硬化胶凝材料的发展前景。     

Novel fabrication of more homogeneous water-soluble binder system feedstock by surface modification of oleic acid

Compared to conventional debinding process of wax-based binders used in ceramic injection molding, polyethylene glycol-based binders (water-soluble binders) with its high efficiency and environmental acceptability have appeared as a good alternative. However, water-soluble binder feedstock still presents some problems such as powder–binder separation or particle segregation which limits injected parts’ final properties. In the present work, we have successfully prepared the more homogeneous water-soluble feedstock with lower shear viscosity by a prior ball milling treatment to induce a small quantity of oleic acid to the surface of zirconia powders before the mixing process. Also, the surface modification mechanism of oleic acid to zirconia powders has been systematically discussed. With the modified powder, as-leached part with less agglomeration and phase separation has been fabricated, which suggests a novel modification method for fabricating injection molded ceramic parts by using water-soluble binders.     

Characterization of the Plasticized GAP/PEG and GAP/PCL Block Copolyurethane Binder Matrices and its Propellants

Though glycidyl azide polymer (GAP) is a well‐known and promising energetic polymer, propellants based on it suffer from poor mechanical and low‐temperature properties. To overcome these problems, plasticized GAP‐based copolymeric binders were prepared and investigated through the incorporation of flexible‐structural polyethylene glycol (PEG) and polycaprolactone (PCL) into a binder recipe under a Desmodur N‐100 polyisocyanate (N‐100)/isophorone diisocyanate (IPDI) (2 : 1, wt. ratio) mixed curative system. The nitrate esters (NEs) or GAP oligomer were used as energetic plasticizers at various ratios to the polymers. The GAP/PCL binders held the plasticizers much more than the GAP/PEG binders did. The glass transition temperatures (T_g) of segmented copolymeric binders were more dependent on the plasticizer level than the PEG or PCL content. The increase in the plasticizer content decreased the mechanical strength and modulus of binders, while the change of strain was modest. Finally, the NE plasticized GAP‐based solid propellants showed enhanced mechanical and thermal properties by the incorporation of PEG or PCL. The properties of GAP/PCL propellants were superior to those of GAP/PEG propellants.     

无烟煤型焦反应性的研究

以无烟粉煤为主配料,分别添加ＲＳＬ和ＲＳＦ两种热塑性粘结剂。采用冷压成型高温干留制备型焦的工艺,获得几种无烟煤型焦样品,并对其进行了反应性测试。重点研究了无烟煤煤阶和粘结剂对型焦反应性的影响,为便于分析,同时对粘结剂和原料无烟煤的反应性进行了研究。研究结果表明,煤阶和粘结剂性质是影响型焦反应性的主要因素。型焦反应性随煤阶变化规律与其原料无烟煤一致,说明煤的性质可决定其型焦的反应性;另外,由两种粘结     

Modeling of mold filling process for powder injection molding

The mold filling process has been modeled for the injection molding of different polymer-based binders and powder-polymer mixtures. It is essentially a two dimensional non-Newtonian fluid flow analysis in a non-isothermal environment. A complete analysis is accomplished by combining a finite element method and control volume technique to describe an increment of flow front movement, whereas a finite difference method is used to solve the energy equation to characterize the temperature distribution. Numerical results are compared to exact solutions for a circular ring cavity using a power law fluid model under an isothermal condition. Comparison of computed results against published data for a simple circular disk shows good agreement between the two analysis methods. After making selected comparison studies, it is demonstrated that the filling process in Powder Injection Modeling with different combination of powder-polymer mixtures is markedly dependent on specific combinations of powder; and polymer based binders. Computed flow front results for a rectangular cavity also compared favorably against the data for a power law fluid model under non-isothermal conditions.     

基于桥面铺装材料的橡胶沥青反应机理研究

选择不同的橡胶沥青工艺参数(7种反应时间、3种反应温度和4种胶粉掺量),采用动态剪切流变仪(DSR)以及凝胶渗透色谱(GPC),以研究不同反应参数对橡胶沥青性能的影响.试验结果表明:反应时间和反应温度是影响橡胶沥青性能的最主要因素;反应时间越长,温度越高,橡胶沥青失效温度以及粘度都较高;不同反应参数对基质沥青性能的影响不明显;胶粉改性剂(CRM)掺量对粘度计车辙因子(G*/sinδ)具有显著影响;CRM掺量越高,沥青中大分子(LMS)越高,这主要是由于沥青中小粒径分子被CRM吸收.     

基料和颜料对乳胶漆光泽的影响

研究了建筑涂料中常用的相同基料、不同颜料,及相同颜料、不同基料时,漆膜光泽随颜料体积浓度（ＰＶＣ）变化的关系。随着ＰＶＣ的增加,漆膜光泽逐渐减弱,但不同的基料及颜料对漆膜光泽的变化影响程度不同。主要探讨了漆膜光泽与基料颜料的折射率、密度、粒径的关系。漆膜的光泽随着基料和颜料折射率的增大、粒径的减小而增大;随着颜料密度增加、颜料分散性降低而减弱。     

含碳耐火材料用结合剂的现状及改进意见

介绍了含碳耐火材料用结合剂的生产现状、工艺过程、产品优缺点及其对成品砖质量的影响情况,并提出了提高各类结合剂质量的改进措施。     

Hydration of CAC cement in a castable refractory matrix containing processing additives

A growing demand for refractory castables with a particular behavior has been inducing a continuous technological evolution, where one of the most important aspects, is an in-depth knowledge of hydraulic binders. These materials greatly influence the rheological properties and mechanical strength evolution of castables, defining their workability range and demolding time, respectively. The hydration process of hydraulic binders is influenced by the presence of matrix and additives (dispersants and accelerators), which affect the setting and demolding time of shaped bodies. In this work, the influence of these variables on the hydration process of calcium aluminate cement was studied by means of temperature measurements, oscillatory rheometry and normal force measurement. These techniques were able to evaluate the setting behavior of different binders, either in plain water or in matrix-representative suspensions. In both cases, the dispersants presented a retarding effect on the hydration process, which was more significant for citric acid and diammonium citrate. The combination of these additives with an accelerator (Li₂CO₃) was shown to be an efficient tool to control the setting time of castables.     

粉煤成型机理研究进展

综述了粉煤成型机理研究进展。褐煤无粘结剂成型机理有沥青、腐植酸、毛细孔等多种假说,这些假说都认为,煤“自身粘结剂”的丰厚 成型的重要基础;粉煤在粘结剂成型过程中,煤与粘结剂间相互润湿是成型的前提条件,进而依靠内聚力和粘附力使粉煤成型。本项研究将为开发粘结剂及成型新工艺提供理论依据。     

Influence of the ice front velocity and of the composition of suspensions on thermal properties of bentonite materials prepared using freeze–casting process

The influence of (i) the ice front velocity in the freeze–casting process as well as the addition of two binders, (ii) the inorganic synthetic mineral laponite and (iii) the natural organic oligomer chitosan, on the microstructure and on thermal conductivity of bentonite materials prepared using the freeze–casting process were investigated by scanning electron and interferometric microscopies and the laser flash method. Prior to measurements, materials physico-chemical characteristics were determined using specific surface area, grain size and density measurements. Results show that the width of the strongly oriented pores obtained with the freeze–casting process is modified by the presence of binders, and that in turn, the thermal conductivity and anisotropy are also significantly modified.     

Effect of different binders on reconstitution behaviors and physical,structural, and morphological properties of fluidized bed agglomerated yoghurt powder

Abstract

Fluidized bed agglomeration is a widely used technique in the production of instant food powders. In this process, primary particles are agglomerated to give a granule-shaped product with improved instant characteristics compared to the original primary particles. Instant products are easy to use by the consumers and hence are favored over the unagglomerated particles. Depending on the type of binder used and process conditions, agglomerates exhibit different shapes, structures and instant properties. In this study, spray-dried yoghurt powders were agglomerated in a top sprayed fluid bed granulator. The influence of different binders (distilled water, ionic, and sugar-based solutions) on agglomeration growth mechanism, particle morphology, and chemical bonds were investigated. The results showed that sugar-based binders caused large particle size and porosity compared to water binders (p?<?0.05). Hydrophilic sugars also improved wettability. b* value of powders enhanced with sugar binders. Protein and stretching vibration of N–H groups were affected by acidity of water and resulted in an improvement of powder solubility. Circularity of particles decreased with the usage of hydrophilic sugar solutions while elongation increased.     

Synthesis and Characterization of Geopolymer from Bayer Red Mud with Thermal Pretreatment

A composite geopolymeric material was synthesized from Bayer red mud combined with granulated blast‐furnace slag. Thermal pretreatment was applied to improve the solubility of red mud in alkaline solution to promote geopolymerization. The dissolution efficiencies of alumina and silica reached a maximum when red mud was calcined at 800°C, resulting in the highest compressive strength of binders. It was demonstrated that a higher solubility of calcined red mud led to a higher strength of the composite binders. The characteristic microstructures of hydration products were studied to illustrate the geopolymerization process by XRD, FTIR and SEM. The results showed that aluminosilicates were dissolved in the alkaline solution to form nanostructural particulates during the early dissolution process, and then accumulated to form highly dense geopolymeric matrices through solidification reaction. The coexistence of geopolymer and C–(A)–S–H is suggested to contribute to the good performance of the composite binders.     

镍矿渣地聚合物的制备及其增韧改性

以工业固体废渣-水淬镍渣为主要原料,在碱激发剂作用下制备地聚合物.通过加入矿渣和纤维的方法对镍渣地聚合物的力学性能进行优化,并通过孔结构测试、断面形貌分析等方法,对矿渣的增强作用和纤维的增韧作用进行研究.结果表明:矿渣的掺入有利于镍渣地聚合物抗压强度的提高和内部孔径结构的改善.50 ℃养护7 d时,与镍渣地聚合物相比,矿渣掺量为50％的镍矿渣地聚合物的抗压强度提高了209.7％,总孔隙率和最可几孔径尺寸分别降低了32.7％和53.1％.PP纤维的掺入能有效提高镍矿渣地聚合物的韧性,当纤维掺量为1.6％时,50 ℃养护7 d的镍矿渣地聚合物抗折强度和抗冲击功分别较未掺纤维试样提高了42.0％和114.3％,基体中纤维的拔出和拉断消耗了荷载能量,提高了地聚合物的抗裂能力.     

Heat Evolution Tests with Calcium Aluminate Binders and Castables

A simple device is described for the determination of the rate of temperature increase during the hydration of calcium aluminate binders and castables under semiadiabatic conditions. Automatically recorded time-temperature curves are shown for commercial binders of various compositions. The complex relations between the rate of heat evolution and other properties of commercial and synthetic binders were studied by varying such factors as composition, crystal development, and fineness of the binder. The effect of additions of polyelectrolytes was also explored. It was found that, for a given binder composition, the thermal history of the binder and the amount of admixtures influenced the rate of hydration most markedly. Some correlation between heat evolution and strength development was indicated.