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1.
针对现阶段恒流变合成基钻井液基础油成本高昂且不可再生的缺陷,研究具有廉价、环保、可再生优势的生物柴油基恒流变钻井液技术。优选原材料制备成本低、环保且低温流动性好的大豆油乙酯生物柴油作为基础油,通过选择高油水比,并在辅乳化剂中引入阳离子表面活性剂,有效减缓了生物柴油基乳液因高温水解、皂化导致的增稠现象。使用由阳离子改性剂十六烷基三甲基氯化铵所制备的有机土可改善钻井液的流变性、稳定性和滤失造壁性,且不会引起低温稠化。使用二聚脂肪酸和椰子油脂肪酸二乙醇酰胺合成恒流变流型调节剂,可在生物柴油基中形成强网络结构并有效调控恒流变性。建立一套密度为1.2g/cm~3的生物柴油基恒流变钻井液体系,恒流变温差范围达2~90℃,抗温达160℃,可抗5%海水、10%页岩屑污染,环保性能优良。  相似文献   
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Novel inks were formulated by dissolving polycaprolactone (PCL), a hydrophobic polymer, in organic solvent systems; polyethylene oxide (PEO) was incorporated to extend the range of hydrophilicity of the system. Hydroxyapatite (HAp) with a weight ratio of 55–85% was added to the polymer-based solution to mimic the material composition of natural bone tissue. The direct ink writing (DIW) technique was applied to extrude the formulated inks to fabricate the predesigned tissue scaffold structures; the influence of HAp concentration was investigated. The results indicate that in comparison to other inks containing HAp (55%, 75%, and 85%w/w), the ink containing 65% w/w HAp had faster ink recovery behavior; the fabricated scaffold had a rougher surface as well as better mechanical properties and wettability. It is noted that the 65% w/w HAp concentration is similar to the inorganic composition of natural bone tissue. The elastic modulus values of PCL/PEO/HAp scaffolds were in the range of 4–12 MPa; the values were dependent on the HAp concentration. Furthermore, vancomycin as a model drug was successfully encapsulated in the PCL/PEO/HAp composite scaffold for drug release applications. This paper presents novel drug-loaded PCL/PEO/HAp inks for 3D scaffold fabrication using the DIW printing technique for potential bone scaffold applications.  相似文献   
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分散颗粒形态对抗冲共聚聚丙烯的冲击强度有较大影响。综述了影响分散颗粒形态的因素,包括等规聚丙烯的分子结构和丙烯均聚工艺、等规聚丙烯和乙丙橡胶之间的相容性、长丙烯链段乙烯-丙烯嵌段共聚物的分子结构及其对等规聚丙烯和乙丙橡胶之间相容性的增强作用、长乙烯链段乙烯-丙烯嵌段共聚物的分子结构及其对乙丙橡胶流变性的干扰等。调整共聚反应的乙烯与烯烃摩尔比可以有效改善抗冲共聚聚丙烯分散颗粒的形态。  相似文献   
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While protein medications are promising for treatment of cancer and autoimmune diseases, challenges persist in terms of development and injection stability of high-concentration formulations. Here, the extensional flow properties of protein-excipient solutions are examined via dripping-onto-substrate extensional rheology, using a model ovalbumin (OVA) protein and biocompatible excipients polysorbate 20 (PS20) and 80 (PS80). Despite similar PS structures, differences in extensional flow are observed based on PS identity in two regimes: at moderate total concentrations where surface tension differences drive changes in extensional flow behavior, and at small PS:OVA ratios, which impact the onset of weakly elastic flow behavior. Undesirable elasticity is observed in ultra-concentrated formulations, independent of PS identity; higher PS contents are required to observe these effects than in analogous polymeric excipient solutions. These studies reveal novel extensional flow behaviors in protein-excipient solutions, and provide a straightforward methodology for assessing the extensional flow stability of new protein-excipient formulations.  相似文献   
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Persistent froth is becoming more and more common in coal and mineral flotation plants and presents safety and operational challenges. No effective method has been developed to destabilise persistent froth. As a new initiative, this study examined the structural difference between persistent foam and coal froth, based on which a solution was developed to maximumly destabilise coal froth. Destabilisation test, oscillatory rheology measurement and scanning electron microscopy (SEM) analysis indicated that the coal froth was more stable than the foam due to the formation of thin capillaries and tightly arranged coal particles on bubble surfaces. Although 107 µm silicone oil droplet could completely destabilise the foam at 2 mmol/L concentration, it only destabilised less than 50% coal froth even at 6 mmol/L concentration. To maximumly destabilise the coal froth formed by −38 and −20 µm particles, 24 and 18 µm silicone oil droplets were required to pass through the thin capillaries and enter the bubble films, respectively. However, smaller silicone oil droplets could not bridge the bubble films to destabilise coal froth and therefore a critical droplet size occurred depending on the size of particles stabilising the froth.  相似文献   
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The aim of this study was to optimize the composition of the chloroprene rubber (CR) composites crosslinked via the Heck-type reaction to ensure their safe processing at elevated temperature. The developed curing system consisting of iron (III) acetylacetonate (Fe(acac)) and triethanolamine (TEOA) demonstrates high activity and more eco-friendly composition in comparison with metal oxide system, commercially used for CR crosslinking. However, the high activity of Fe(acac)/TEOA system results in a short scorch time, which is the greatest disadvantage regarding the safe processing of CR rubber and thus, must be improved. Therefore, CR compounds with Fe(acac) in the presence of different additives were studied. The longest scorch times (t02) were observed for rubber compounds with urotropine (U), N-cyclohexyl-2-benzothiazole sulfenamide (CBS) or salicylic acid. Moreover, vulcanizates containing these additives exhibited higher tensile strengths and elongation at breaks compared to CR crosslinked with Fe(acac)/TEOA system.  相似文献   
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This study explored the feasibility of using torrefied biomass as a reinforcing filler in natural rubber compounds. Carbon black was then replaced with the torrefied biomass in elastomer formulations for concentrations varying from 0% to 100% (60 parts per hundred rubber or phr total). Their influence on the curing process, dynamic properties, and mechanical properties was investigated. Results were compared with the properties of vulcanizates containing solely carbon black fillers. Time to cure (t90) for compounds with torrefied biomass fillers increased, while filler-filler interactions (ΔG') decreased, compared to carbon black controls. At low strains, the tan δ values of the torrefied fillers vulcanizates were similar to the controls. Incorporation of torrefied biomass into natural rubber decreased compound tensile strength and modulus but increased elongation. Replacement with torrefied fillers resulted in a weaker filler network in the matrix. Still, results showed that moderate substitution concentrations (~20 phr) could be feasible for some natural rubber applications.  相似文献   
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It is important from both a strategic and economic standpoint to study the mechanism of formation of water/oil emulsions, to predict their increase of viscosity with respect to that of the crude oil, and to obtain information about the stability vs separation of these substances (since their presence can impair oil processing and distribution). The objective of this work was to ascertain the influence of monoethylene glycol (MEG) on these parameters and its action mechanism. The addition of MEG in different proportions in the oil emulsions significantly changed the flow curve of the emulsion, passing from a quasi-Newtonian one to a shear thinning behaviour. Besides this, when MEG was present at low concentrations, the demulsification process was slow and an increase in concentration made the emulsions more stable than samples containing the same aqueous phase proportion. Under the conditions studied, the addition of MEG did not reduce the quantity of the aqueous phase separated compared to the emulsions free of MEG, but significantly delayed the demulsification process. Rheology provided important information regarding the phase separation process of the aqueous phase in oil phase emulsions, and dynamic testing suggested that the most relevant effect of the addition of MEG is an increase of the emulsion elasticity that can be correlated with the increase in the emulsion stability observed by bottle test and Turbiscan.  相似文献   
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自密实混凝土具有高流动性、抗离析性及较好的自密实性等特点,有利于提升工程质量及降低工程成本。将再生骨料应用于自密实混凝土中,可实现建筑废弃物的循环利用。为了确保自密实再生混凝土在工程应用过程中的可行性与安全性,还需在其工作性与力学性能等方面进行大量改性研究。基于自密实混凝土的流变密实机理,归纳总结了自密实混凝土的配合比设计原理,总结并评述了自密实再生混凝土的工作性能、力学性能的研究进展。最后,分析了自密实再生混凝土工作及力学性能研究所存在的问题,并对其前景进行展望,有助于推动自密实再生混凝土大规模地应用于实际工程中。  相似文献   
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