渗透型密封固化剂对混凝土性能的影响

在不同混凝土路面上分别涂刷钠基、钾基和锂基三种不同密封固化剂,测试了6个密封固化剂样品对混凝土路面的强度、硬度和耐磨性的影响,并测试了锂基密封固化剂对混凝土渗水深度、抗渗等级、氯离子扩散系数和碳化性能的影响,探讨了密封固化剂的固化机理。结果表明:锂基、钾基和钠基密封固化剂能提高混凝土路面的强度,显著增强混凝土路面的硬度和耐磨性;锂基密封固化剂能明显降低混凝土渗水深度、氯离子扩散系数和碳化深度,提高混凝土的抗渗等级。     

汽车锂基脂行车试验

锂基润滑脂是多效、通用、长寿命润滑脂,也是汽车轮毂轴承润滑的理想润滑脂。目前世界汽车主要生产国多采用锂基润滑脂。我国目前多采用钙基润滑脂或钙钠基润滑脂,其性能差,不耐高温,使用寿命短。解放牌汽车轮毂采用钙基润滑脂.其寿命6000～10000km.     

铁路2号锂基脂研制

<正> 前言目前,我国润滑脂工业中的主要产品为钙基脂和钠基脂,占润滑脂总产量的85％,锂基脂仅占6％。钠基脂耐水性很差,遇水即溶解、流失;钙基脂耐温性差,只能在70℃以下使用,两者的使用寿命都很短。因此,国外逐渐以锂基脂取代钙基、钠基脂。据报道。美国锂基脂增长很快,1957年     

利用废油脂制备钠基润滑脂的初步研究

利用废油脂采用直接法制备出钠基润滑脂,确定了利用废油脂制备钠基润滑脂的最佳配方及工艺条件。使用差动热分析仪对合成出的润滑脂进行了滴点测试,并对其外观简单鉴别,结果表明,利用废油脂替代硬脂酸等脂肪酸制备钠基润滑脂产品是可行的,为废油脂的合理利用开辟了新的途径,但合成的钠基润滑脂滴点较低。在以后的研究中可以尝试制备钙基、钙-钠复合基或锂基润滑脂,以提高润滑脂的滴点和其他性能。     

无机防沉剂对醇基铸造涂料性能的影响

研究了铸造涂料领域常用的无机防沉剂对铸造涂料密度、悬浮性能、剪切稀释性能、屈服值、触变性能的影响,考察的无机防沉剂包括凹凸棒土、活化凹凸棒土、海泡石粉、锂基膨润土、钠基膨润土。结果表明,以凹凸棒土、活化凹凸棒土或者海泡石粉作为无机防沉剂,制备的醇基铸造涂料具有良好的悬浮稳定性、剪切稀释特性和较高的屈服值,而采用较低加入量的海泡石粉或者较高加入量的锂基膨润土或钠基膨润土,制备的涂料具有较好的触变性。     

化学配方

一步法固定头发波浪的无臭液体此无臭液体含硫化合物,氧化促进剂、pH调节剂和载色剂,对头发无损害,经使用后能明显地使头发发亮、柔软和湿润。配方: 含硫基乙醇酸铵0.2 酒石酸0.03 亚硫酸钾0.8碘化钾0. 6 水97.34     

蒙脱石的湿法机械球磨剥离

以内蒙古钙基蒙脱石为原料,通过湿法改型、改性制备了钠基蒙脱石和有机蒙脱石.分别以钙基蒙脱石、钠基蒙脱石和有机蒙脱石为对象,在乙醇中湿法机械球磨、超声处理蒙脱石,利用XRD、TEM、AFM等手段研究了机械球磨法对不同层间离子的蒙脱石剥离效果.结果表明,内蒙古钙基蒙脱石湿法钠化及有机化效果良好,机械球磨法剥离钠基蒙脱石效果最佳,剥离型蒙脱石片层尺寸小于200 nm,其平均厚度约为15 nm;有机蒙脱石层间有机物具有稳定蒙脱石片层的作用,有机改性不能促进机械球磨法对蒙脱石片层的剥离.     

聚丙烯/蒙脱土纳米复合材料的制备与性能研究

以马来酸酐接枝低分子量聚丙烯为相容剂,采用双螺杆挤出机熔融挤出法,制备插层型聚丙烯/有机钠基蒙脱土、聚丙烯/酸化有机化钠基蒙脱土、聚丙烯/钠基蒙脱土3种纳米复合材料,发现有机钠基蒙脱土、酸化有机化钠基蒙脱土和钠基蒙脱土对PP力学性能和燃烧性能均有一定程度的提高。经X射线衍射(XRD)和扫描电子显微镜(SEM)观察,发现有机钠基蒙脱土片层间距增幅最大,复合材料的燃烧性能也有很大提高。     

磷铝酸盐水泥基灌浆材料流变性能及保水性能

采用低pH值水泥基材料固化高放射废弃物具有很好的优势,而水泥基灌浆材料的流变性能是评价高放废物深地质处置用灌浆材料的重要指标之一.探究了水灰比、外加剂对磷铝酸盐水泥流变性能以及保水性能的影响规律.结果表明:水灰比越大,浆体粘度越小,流动性能越好,但浆体越不稳定,越容易离析;而且MgO膨胀剂的掺入,增大了浆体的粘度,其中膨胀剂活性越高,浆体的流变性越差;羟丙基甲基纤维素醚以及钠基膨润土掺入改善水泥浆体保水性能,羟丙基甲基纤维素醚的保水效果优于钠基膨润土,当HPMC掺量大于0.3%,灌浆液不析水;掺加减水剂降低了浆体的粘度,且聚羧酸系减水剂的减水效果优于萘系减水剂,同时减水剂的掺入会使浆体的稳定性下降.     

不同稠化剂润滑脂随温度变化流变性研究

利用MCR-302流变仪,采用温度扫描法,在25℃-190℃研究9种稠化剂润滑脂随温度升高的流变性能。结果表明:随着扫描温度的升高,锂基脂比钙基脂表现出更宽泛的温度适用范围;25℃起复合锂基脂呈凝胶状态前结构保持得最好;脲基脂(芳芳胺)在120℃-125℃凝胶区结构保持能力最强;复合磺酸钙基脂、复合铝基脂、脲基脂(芳短胺)随温度升高表现出一定的变硬趋势;脲基脂(长短链胺)随着储存时间的延长,样品架构保持逐渐变差。     

Novel phosphorus‐containing hardeners with tailored chemical structures for epoxy resins: Synthesis and cured resin properties

A comparative evaluation of systematically tailored chemical structures of various phosphorus‐containing aminic hardeners for epoxy resins was carried out. In particular, the effect of the oxidation state of the phosphorus in the hardener molecule on the curing behavior, the mechanical, thermomechanical, and hot‐wet properties of a cured bifunctional bisphenol‐A based thermoset is discussed. Particular attention is paid to the comparative pyrolysis of neat cured epoxy resins containing phosphine oxide, phosphinate, phosphonate, and phosphate (with a phosphorus content of about 2.6 wt %) and of the fire behavior of their corresponding carbon fiber‐reinforced composites. Comparatively faster curing thermosetting system with an enhanced flame retardancy and adequate processing behavior can be formulated by taking advantage of the higher reactivity of the phosphorus‐modified hardeners. For example, a combination of the high reactivity and of induced secondary crosslinking reactions leads to a comparatively high T_g when curing the epoxy using a substoichiometric amount of the phosphinate‐based hardener. The overall mechanical performance of the materials cured with the phosphorus‐containing hardeners is comparable to that of a 4,4′‐DDS‐cured reference system. While the various phosphorus‐containing hardeners in general provide the epoxy‐based matrix with enhanced flame retardancy properties, it is the flame inhibition in the gas phase especially that determines the improvement in fire retardancy of carbon fiber‐reinforced composites. In summary, the present study provides an important contribution towards developing a better understanding of the potential use of such phosphorus‐containing compounds to provide the composite matrix with sufficient flame retardancy while simultaneously maintaining its overall mechanical performance on a suitable level. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Basic analytical control techniques for epoxy resins and adhesive curing agents

Procedures for determination of basic quality characteristics of epoxide-bisphenol A resins and amine hardeners: the epoxide equivalent and the amine value, respectively; the viscosity; and the pot life are reported. A rapid method for the assessment of the gelation time of a mixture of an epoxy resin with a hardener is described.     

Influence of Curing Agents Molecular Structures on Interfacial Characteristics of Graphene/Epoxy Nanocomposites: A Molecular Dynamics Framework

This paper presents a comprehensive molecular dynamics study on the effects of the stoichiometric ratio of epoxy:hardener, hardener's linear and cyclic structure, and number of aromatic rings on the interfacial characteristics of graphene/epoxy nanocomposite. The van der Waals gap and polymer peak density as a function of the type of the hardener is calculated by analyzing the local mass density profile. Additionally, steered molecular dynamics are used to conduct normal pull-out of graphene to study the effect of the mentioned features of hardeners on the interfacial mechanical properties of nanocomposites, including traction force, separation distance, and distribution quality of reacted epoxide rings in the epoxy. Influence of the hardeners on the damage mechanism and its initiation point are also studied by analyzing the evolution of local mass density profile during the normal pull-out simulation. It is seen that stoichiometric ratio and geometrical structure of the hardeners affect the interfacial strength. It is also revealed that the hardener type can change the epoxy damage initiation point. The damage occurs in the interphase region for a higher stoichiometric ratio or cyclic structure of hardener. In comparison, for hardener's lower stoichiometric ratio and non-cyclic structure, failure begins in the epoxy near graphene layers.     

Effect of polyisocyanate hardener on adhesive force of waterborne polyurethane adhesives

A series of waterborne polyurethane (WBPU)/hardener adhesives were obtained from mixing of WBPU containing different types of polyol as a soft segment with aliphatic and aromatic polyisocyanates hardeners. By characterization of allophanate and biuret bonds formed from the reaction of hardener NCO with urethane/urea groups of WBPU using ¹HNMR spectroscopy. It was found that the optimum number ratio (molar ratio) of NCO group of hardener to urethane/urea group of WBPU that shows the highest adhesion force was depended on the type of hardener (aliphatic/aromatic polyisocyanate) and dimethylol propionic acid (DMPA) content (total content of urethane/urea groups); however independent of the type of soft segment (polyol) of WBPU. The optimum number ratio (molar ratio) of NCO group of aromatic polyisocyanate hardener to urethane/urea was higher than that of aliphatic hardener to achieve the highest adhesion force of WBPU. The adhesive force increased with increasing hardener content up to the optimum point and then decreased. Poly(tetramethylene adipate glycol) (PTAd) based WBPUs with aliphatic hardener show higher adhesive force than Poly(tetramethylene oxide glycol) (PTMG) and aliphatic hardener‐based WBPUs at the optimum number ratio (molar ratio) of NCO group of hardener to urethane/urea group of WBPU. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3663–3669, 2007     

Water absorption in epoxy resins: The effects of the crosslinking agent and curing temperature

Epoxy systems were prepared with the same epoxide (diglycidyl ether of bisphenol A) with five different hardeners: 4,4′‐diaminodiphenylmethane (H1), diethylenetriamine (H2), a cycloaliphatic amine based on isophorone diamine (H3), a polyaminoimidazoline‐based hardener (H4), and a polyamidoamine‐based adduct hardener (H5). Samples were subjected to four different postcure treatment temperatures (23, 55, 75, and 150°C). Water absorption kinetics were obtained for each material and for each postcure treatment. The water absorption behaviors for the materials with H1, H2, and H3 were similar, whereas those for H4 and H5 were quite different. This is discussed in terms of the molecular structures of the hardeners. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2544–2549, 2005     

Molasses and air blown coal tar pitch binders for the production of metallurgical quality formed coke from anthracite fines or coke breeze

The effect of the type and the amount of hardeners, such as ammonium nitrate, ammonium carbonate and nitric acid on the molasses bonded briquettes prepared from anthracite fines or coke breeze were investigated. Amongst the hardener studied the best results were obtained with 2.5% ammonium nitrate hardener. The briquettes produced with this hardener were highly water resistant but not waterproof and their tensile strengths were not adequate to be used as a substitute for the metallurgical coke. Therefore, the briquettes were prepared with molasses containing 2.5% ammonium nitrate hardener and air blown coal tar pitch blended binder. When the blended binder was used for the production of anthracite fines or coke breeze briquettes, after curing at 200 °C for 2 h, they became waterproof and their tensile strengths were found to be sufficient to be used as a substitute for coke oven coke. The briquettes after curing could be directly charged into the blast furnace without carbonizing them at high carbonization temperatures. Since molasses and coal tar pitch, are relatively cheap and readily available materials, the process investigated could be economical way of producing high quality formed coke.     

Natural castor oil based 2-package waterborne polyurethane wood coatings

The effects of four kinds of hardener on the properties of castor oil (CO) based 2-package waterborne polyurethane (2K-WPU) wood coatings were examined. Modified castor oil (MCO) was prepared by transesterification of glycerol and CO at the molar ratio of 2.0. The waterborne polyurethane-dispersed polyol (PUDp), one component of the 2K-WPU, was synthesized from MCO, dimethylol propionic acid (DMPA) and isophorone diisocyanate (IPDI) by the acetone process to provide a prepolymer with a carboxyl and hydroxyl groups. Then the prepolymer was neutralized by triethylamine (TEA) and dispersed into water. After vacuum distillation to remove acetone, the PUDp was obtained and then mixed with four different hardeners: IPDI, hexamethylene diisocyanate (HDI), polyethylene glycol (PEG) modified PIPDI (polymeric IPDI) and PEG-modified PHDI (polymeric HDI). The NCO/OH molar ratio of 1.5 was used and a 2K-WPU coating was obtained. The results showed that the film of the 2K-WPU coatings obtained from IPDI hardener had excellent gloss and hardness. On the contrary, the film containing PEG-modified PIPDI hardener (PEG-PIPDI) had lower hardness and gloss but higher tensile strength. The film containing PEG-modified PHDI hardener (PEG-PHDI) showed the best elongation at break, abrasion resistance and impact resistance, though it had the worst hardness. The film with HDI hardener had the best hardness and highest tensile strength and superior water resistance among all the films with different hardeners, and it was suitable for wood coatings.     

MONITORING THE SURFACE TENSION OF REACTIVE EPOXY-AMINE SYSTEMS UNDER DIFFERENT ENVIRONMENTAL CONDITIONS

Two commercially available amine-cured epoxy resin formulations were studied under different environmental conditions with regard to the surface tension evolution using axisymmetric drop shape analysis (ADSA). By employing a new strategy, ADSA was used to monitor simultaneously the surface tension and the density of these reactive mixtures from sessile drops. The kinetics of the bulk reactions were quantified by Fourier transform infrared (FTIR) spectroscopy, and the changes in the molecular composition of the surface region were studied by X-ray photoelectron spectroscopy (XPS).

In both formulations, the surface tension values of the amine hardeners were lower than those of the epoxy resins. For one system, the surface tension of the mixture was similar to the surface tension of the hardener. In this case, the hardener migrates to the surface and determines the surface tension of the mixture, as could be proved by XPS measurements. In the other case, the surface region contained only a very small amount of nitrogen, indicating that the nitrogen-containing groups of the hardener were not enriched in the surface region of this mixture. Its surface tension was similar to that of the pure epoxy resin.

In a controlled argon atmosphere, the surface tension of the reactive epoxy-amine systems considered here changed very little as the curing reaction proceeded. The time-dependent changes of the surface tension of the mixtures were caused by environmental factors, particularly the presence of carbon dioxide and water. Such factors can produce complicated surface tension responses due to surface reactions with the amine hardener. The extent of these changes can be controlled by the migration of the hardener to the surface region.     

Epoxy resin particles, 2. An efficient synthetic method of epoxy resin particles in organic solvent by the aid of modified polyolefins as dispersant

Epoxy resin particles were efficiently prepared by addition of Bisphenol A diglycidyl ether to a solution of polyamine hardener in organic solvents containing polyolefin dispersants modified with maleic anhydride and maleimide. Aliphatic hydrocarbons and their mixtures with aromatic hydrocarbons were used as the reaction solvents. The size and size distribution of the particles could be controlled by modulating the difference in solubility parameter between the solvent and the polymer and by changing the reaction temperature. Smaller particles were formed when combined with more highly reactive amine hardeners. The particles prepared by this method showed a rough surface probably because of the polymer deposition on the finally formed particles in the final reprecipitation process. The present synthesis can afford an efficient method for manufacturing the epoxy resin particles in large scale.     

Rheological study of gel phenomena during epoxide network formation in the presence of sepiolite

The dynamic behaviour during the crosslinking of an epoxy polymer near the gel point was monitored using rheological multiple frequency experiments. The influence of a needle‐shaped inorganic nanofiller, sepiolite, either non‐modified or organically surface modified during the cure process in the presence of an aliphatic and an aromatic hardener was investigated. The validity of various criteria for determining the gel point was examined for the crosslinking of these filled thermosets. The Winter–Chambon criterion at the gel point is obeyed by the unfilled and by the non‐modified sepiolite‐filled epoxy matrix with either of the two hardeners. However, physical gels are formed in the presence of the organically modified sepiolite and the Winter–Chambon criterion is not valid. For all the systems investigated, the nanofiller reduces the time to reach gelation. Critical relaxation exponents and gel strength have been determined indicating a more elastic and stronger gel in the presence of the aliphatic hardener. © 2012 Society of Chemical Industry