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941.
Dr. Xiuchao Yao Lin Ni Prof. Chang Yu Mengdi Zhang Qianbing Wei Huawei Huang Wei Guo Hongling Huang Jiangwei Chang Prof. Jieshan Qiu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(60):13683-13687
The Pd/C catalysts are widely used in synthesis of fine chemicals in industry, but their production suffers from a complicated two-step process involving impregnation and reduction, and requires large amounts of solvents and reductant, which would lead to a series of issues such as time consumption, resource waste and environmental pollution. Herein, ultra-small Pd nanoparticles uniformly anchored on carbon nanotubes (Pd/CNTs) were synthesized by using a one-pot and low-temperature reduction strategy. The present process/technology is very sensitive to and controlled by the supports and solvents, and the carbon support and acetic acid synergistically play crucial and decisive roles in the fast production of Pd/C catalysts. Also, the used solvents can be recycled and reutilized, which meets the requirements of sustainable chemistry and green economy. When the as-obtained Pd/CNTs catalyst was used to catalyze the oxidation of benzyl alcohol to benzaldehyde, it achieved a conversion efficiency as high as 99.3 % and a high selectivity up to >99.9 %. The simple, scalable and environmentally friendly strategy can be extended to anchor Pd nanoparticles on various carbon substrates, which sheds a new light on the synthesis of Pd/C catalysts. 相似文献
942.
Pranabesh Sahu Anil K. Bhowmick 《Journal of polymer science. Part A, Polymer chemistry》2019,57(6):738-751
Motivated by the growing demand for greener and sustainable polymer systems, self‐healing elastomers were prepared by emulsion polymerization of terpene and furfural‐based monomers. Both the method and the monomers were green and sustainable. The synthesized copolymers showed molecular weights between 59,080 and 84,210 Da and glass‐transition temperature (Tg) between ?25 and ?40 °C, implying rubbery properties. A set of one‐dimensional (1D) and two‐dimensional (2D) NMR spectroscopy supported the formation of the copolymer and nuclear spin–spin coupling in the copolymer. Reactivity ratios were determined by conventional linear method. A thermoreversible network was achieved for the first time by reacting the furan‐based polymer with bismaleimide (BM) as a crosslinker, via a Diels?Alder (DA) coupling reaction. The reversible nature of the polymer network was evidenced from infrared and NMR spectroscopy. The thermoreversible character of the DA crosslinked adduct was confirmed by applying retro‐DA reaction (observed in differential scanning calorimeter [DSC] analysis) and mechanical recovery was verified by repeated heating and cooling cycles. The network polymers displayed excellent self‐healing ability, triggered by heating at 130 °C for 4–12 h, when their scratched surface was screened by microscopic visualization. The healing efficiency of the crosslinked DA‐adduct was calculated as 78%, using atomic force microscopy. This work provides a green and efficient approach to prepare new green and functional materials. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 738–751 相似文献
943.
Ruibo Ren Zeyu Zhang Jingtao Shi Kechao Han Ziqiao Yang 《Journal of Dispersion Science and Technology》2019,40(5):627-633
Using biomass residue as a source of carbon precursors, a pyrolysis method was used to prepare biomass-derived luminescent Carbon Quantum Dots (CQDs). The prepared CQDs exhibited excellent fluorescence and luminescence properties and fluorescence behaviors of CQDs acquired at different pyrolysis temperatures varied. Importantly, the CQDs showed superior surface activity and the styrene-in-water Pickering emulsion prepared using the CQDs as nano-sized surfactant was highly stable: the higher the pyrolysis temperature the better the stability of the emulsion. In addition, there was no stratification found in the emulsion which was stabilized by the CQD500 (CQDs prepared at 500?°C) after holding for 72?hours. This research provided an approach for preparing the surfactants of nano-sized particles in large scale. The CQDs prepared using the proposed methods are expected to have a high number of potential applications. 相似文献
944.
Zhaojin Lu Huiqing Luo Ziqiang Hu Fulong Pang 《Journal of Dispersion Science and Technology》2019,40(3):415-424
Water-in-oil emulsion separation through a fibrous media bed is a complex process in industries. In this article, in order to select the optimal fibrous material for the separation of water-oil emulsion, three types of commercial fibers as fibrous beds were used to separate water from diesel oil. Based on the principle of orthogonal experimental design, a series of experiments were performed to investigate the effect of such parameters as bed porosity (0.77-0.89), bed length (100-400?mm) and settlement length (120-480?mm) on the separation efficiency and the superficial velocity, and then three parameters were optimized to achieve good separation performance. The experiment showed that the separation efficiency could reach 77% and the flow velocity could reach 30?m/h under the optimal bed structure and stable working conditions. The results of this paper could provide basic designing reference for the industrial application of fibrous bed coalescer. 相似文献
945.
电阻法检测乳化液润滑状态的变化 总被引:2,自引:0,他引:2
用改进的电阻法测定了金属滑动摩擦副在混合润滑状态下发生接触的时间比率,并且检测了环-块试验过程中水包油型乳化液润滑状态的变化,同时还就乳化液中油相的体积分数和载荷等对乳化液成膜能力的影响进行了试验研究.根据测得的金属接触时间比率-滑动速度曲线的变化趋势,可以清楚地判断出润滑状态的转化及对应的临界转化速度.对比相应工况下油膜厚度的理论计算值,可以说明环-块接触区会形成一个基油富集区(油池).在此区域内,乳化液中油相的体积分数远比其标称值高,乳化液润滑具有油池润滑的特点 相似文献
946.
A. G. Petrova 《Journal of Applied Mechanics and Technical Physics》2007,48(5):671-679
It is proved that the problem of one-dimensional motion of an emulsion under the action of thermocapillary forces has a self-similar
solution in a semi-infinite interval. The behavior of the solution is illustrated by numerical examples for aluminum-lead
emulsions, in which the carrier phase is lead or aluminum. The solution is compared with the solution of the self-similar
problem linearized in the low impurity concentration.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 5, pp. 61–70, September–October, 2007. 相似文献
947.
Polystyrene (PSt) microspheres with diameter of 375 nm to be used as the seeds for seeded emulsion polymerization were prepared via emulsion polymerization using potassium persulfate (KPS) as initiator in ethanol-water mixed solvents.Emulsifier-free seeded emulsion copolymerization of styrene (St) with acrylonitrile (AN) was carried out in the presence of poly(ethylene glycol) monomethoxymonomethacrylate (PEGm)macromonomer as reactive stabilizer and 2,2'-azobisisobutyronitrile (AIBN) as initiator to obtain submicron-sized PEGm graft poly(styrene-co-acrylonitrile) (PEGm-g-PSAN) composite particles with unique morphology.Scanning electron microscopy (SEM) indicated that St and AN together contributed to forming the unusual morphology.The concentration of St and AN,total monomer concentration,initiator type and the monomer adding method remarkably affected the morphology of the composite polymer particles. 相似文献
948.
为了研究瞬态爆炸温度场分布规律,基于高速相机、黑体辐射理论、图像传感器的拜尔阵列和自编python代码,构建了依据比色测温原理的高速二维温度测试系统,并对添加不同含量TiH2的乳化炸药、TiH2粉尘以及C2H2气体的爆炸温度场进行了测量。实验结果表明:TiH2的加入可以显著提高炸药的爆炸温度和火球持续时间,当乳化炸药中的TiH2质量分数为6%时,爆炸平均温度最大值为3048 K,相比纯乳化炸药提高了41.5%;此外,TiH2粉尘云火焰平均温度呈现先增大,再稳定,最后减小的趋势,浓度为500 g/m3的粉尘云火焰平均温度高于浓度为833 g/m3的平均温度,其最高平均温度分别为2231 和 2192 K;10%C2H2/90%空气预混气体(即体积分数为10%的C2H2和90%空气组成)的早期火焰温度均匀,内部略低于边缘温度,随着火焰膨胀,火焰边缘温度逐渐升高,火焰平均温度开始降低。与传统爆炸测温手段相比,比色测温方法可以准确测量某区域的瞬态爆炸温度,获得温度分布云图,为研究瞬态爆轰温度规律及影响因素提供了一种新的技术手段。
相似文献949.
950.