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991.
Xiang Ren Jingyuan Sun Zhengliang Huang Yao Yang Sihang Tian Jingdai Wang Yongrong Yang 《American Institute of Chemical Engineers》2020,66(5):e16909
Nowadays, the droplet–particle collision characteristics in the gas-phase ethylene polymerization process are still unclear. The high-speed photography and a quasi-circle imaging approach are employed to study the collision interaction characteristics between liquid droplets and polyethylene particles. The liquid film evolution is studied through variations of the film thickness on the particle north pole, the dynamic contact angle, center angle and film thickness at the maximum extension. Results have found that for n-hexane the threshold temperature of the recoil happening increases with increasing initial Weber number, but for 1-hexene it is stable. Over 70°C evaporation and splash occurs immediately. Under low Weber numbers, the water droplet stays for damping oscillations, the reference stable height of which is linearly related to temperatures. Moreover, three regimes of film thickness variation with time are identified and mathematically described, while Regime 3 characteristics are found strongly dependent on the liquid species, Weber number, and particle temperature. 相似文献
992.
993.
Niels J. Sijbrandi Ad J. Kimenai Edwin P.C. Mes René Broos Georg Bar Martin Rosenthal Yaroslav I. Odarchenko Dimitri A. Ivanov Jan Feijen Pieter J. Dijkstra 《Polymer》2012,53(19):4033-4044
Segmented poly(ether ester amide)s comprising glycine or β-alanine extended bisoxalamide hard segments are highly phase separated thermoplastic elastomers with a broad temperature independent rubber plateau. These materials with molecular weights, Mn, exceeding 30 × 103 g mol?1 are conveniently prepared by polycondensation of preformed bisester–bisoxalamides and commercially available PTHF diols. FT-IR revealed strongly hydrogen bonded and highly ordered bisoxalamide hard segments with degrees of ordering between 73 and 99%. The morphology consists of fiber-like nano-crystals randomly dispersed in the soft polymer matrix. The micro-structural parameters of the copolymers were addressed by simultaneous small- and wide-angle X-ray scattering. It is shown that the crystals have strictly identical thickness, which is close to the contour length of the hard segment. The long dimension of the crystals is identified with the direction of the hydrogen bonds. The melting transitions of the hard segments are sharp, with temperatures up to 170 °C. The studied polymers have an elastic modulus in the range of 139–170 MPa, a stress at break in the range of 19–31 MPa combined with strains at break of higher than 800%. The segmented copolymer comprising the β-alanine based bisoxalamide hard segment with a spacer of 6 methylene groups has a melting transition of 141 °C which is higher than the melting transition of its glycine analogue of 119 °C. Likewise, the fracture stress increased from 22 to 31 MPa when the glycine ester group in the hard segment was replaced with β-alanine. The improved thermal and mechanical properties of the latter polymers is related to the crystal packing of the β-alanine based hard segments in the copolymer compared to the packing of the hard segments comprising glycine ester groups. 相似文献
994.
UHMWPE微粉辐照接枝MAH的研究 总被引:2,自引:0,他引:2
采用辐照方法在超高分子量聚乙烯(UHMWPE)微粉表面接枝马来酸酐(MAH),用水在UHMWPE膜上的润湿角作为目标函数,依据试验优化设计和灰色系统控制理论,研究了辐照剂量、微粉的粒度和MAH单体的浓度对润湿角的影响。研究结果表明:所考查的三因数对润湿角的影响程度是不同的,影响顺序为:辐照剂量>UHMWPE微粉粒度>MAH浓度。从关联角度看,三因素对润湿角的关联度没有明显的差别,表明在UHMWPE微粉辐照接枝的反应过程中,所考查的三因素对接枝反应过程的影响是互相促进、互相影响、互相补充的。由于辐照剂量在UHMWPE的接枝反应中是比较重要的因素,因此在接枝反应中要严格控制其辐照剂量,其次注意微粉粒度,适当调整单体加入量。至于交互作用,尚需进一步进行研究探讨。 相似文献
995.
简述了镀锌钢铁管和玛钢管配件实施内衬塑的特性及应用概况,重点阐述了衬塑方法和注塑模具的特殊设计结构。 相似文献
996.
本研究建立了微波消解样品,电感耦合等离子体质谱法测定水果中微量元素含量的方法。采用HNO3+H_2O_2+H2O(5/2/2,V/V/V)作为微波消解的酸体系,并利用程序升温控制溶样。在选定的实验条件下,本方法的最低检出限为0.1 ng/g~13.5 ng/g,相对标准偏差为0.98%~3.50%,回收率为96.7%~103.7%,在0.001 mg/L~0.500 mg/L范围内呈良好的线性关系(r≥0.9997),具有操作简单、快速、灵敏度高、抗离子干扰能力强的优点,完全适用于快速准确测定水果中的微量元素。 相似文献
997.
998.
Design and screening of ionic liquids for C2H2/C2H4 separation by COSMO‐RS and experiments 下载免费PDF全文
Xu Zhao Qiwei Yang Dan Xu Zongbi Bao Yi Zhang Baogen Su Qilong Ren Huabin Xing 《American Institute of Chemical Engineers》2015,61(6):2016-2027
Ionic liquids (ILs) have been proposed as promising solvents for separating C2H2 and C2H4, but screening an industrially attractive IL with high capacity from numerous available ILs remains challenging. In this work, a rapid screening method based on COSMO‐RS was developed. We also present an efficient strategy to improve the C2H2 capacity in ILs together with adequate C2H2/C2H4 selectivity with the aid of COSMO‐RS. The essence of this strategy is to increase molecular free volume of ILs and simultaneously enhance hydrogen‐bond basicity of anions by introducing flexible and highly asymmetric structures, which is validated by a new class of tetraalkylphosphonium ILs featuring long‐chain carboxylate anions. At 298.1 K and 1 bar, the solubility of C2H2 in ILs reaches 0.476 mol/mol IL, very high for a physical absorption, with a selectivity of up to 21.4. The separation performance of tetraalkylphosphonium ILs to the mixture of C2H2/C2H4 was also evaluated. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2016–2027, 2015 相似文献
999.
1000.