Tuning of shear thickening behavior and elastic strength of polyvinylidene fluoride via doping of ZnO-graphene

ZnO rice like nonarchitects are grafted on the graphene carbon core via a rapid microwave synthesis route. The prepared grafted systems are characterized via XRD, SEM, RAMAN, and XPS to examined the structural and morphological parameters. Zinc oxide grafted graphene sheets (ZnO-G) are further doped in β-phase of polyvinylidene fluoride (PVDF) to prepare the polymer nanocomposites (PNCs) via mixed solvent approach (THF/DMF). β-phase confirmation of PVDF PNCs is done by FTIR studies. It is observed that ZnO-G filler enhances the β-phase content in the PNCs. Non-doped PVDF and PNCs are further studied for rheological behavior under the shear rate of 1–100 s⁻¹. Doping of ZnO-G dopant to the PVDF matrix changes its discontinuous shear thickening (DST) behavior to continues shear thickening behavior (CST). Hydrocluster formation and their interaction with the dopant could be the reason for this striking DST to CST behavioral change. Strain amplitude sweep (10⁻³% -10%) oscillatory test reveals that the PNCs shows extended linear viscoelastic region with high elastic modulus and lower viscous modulus. Effective shear thickening behavior and strong elastic strength of these PNCs present their candidature for various fields including mechanical and soft body armor applications.     

Chemistry enhanced shear thickening polishing of Ti–6Al–4V

To obtain the great surface quality of Ti–6Al–4V and achieve high efficiency in the polishing process, the chemistry enhanced shear thickening polishing (C-STP) was proposed, and the polishing performance of different pH slurry was studied. The results show that the material removal rate gradually increases as the pH value decreases from 10 to 1, and the best surface quality is obtained at pH 2. The corrosion current density and potential were measured by potentiodynamic polarization under three typical pH values. It is confirmed that the most massive corrosion rate presents at pH 2, and the passive film is most susceptible to be produced at pH 10. The reaction resistance was measured by electrochemical impedance spectroscopy to clarify the polishing mechanism. Under acidic conditions, the chemical reaction product on the surface can be quickly removed by mechanical action of the abrasive. On the contrary, the passive film formed on the surface under the alkaline condition is difficult to be removed. The corrosion reaction products were determined by X-ray photoelectron, and the chemical reaction under acid-base environment was derived. MRR reached 107.3 nm/min under the selected process parameters, and the surface roughness (S_a) is reduced from 124 nm to 8.6 nm within 15 min.     

Heat Transfer Analysis of MHD Power Law Nano Fluid Flow through Annular Sector Duct

Flow and heat transfer analysis of an electrically conducting MHD power law nano fluid is carried out through annular sector duct,under the influence of constant pressure gradient.Two types of nano particles(i.e.Cu and TiO2)are used in power law nano fluid.Strongly implicit procedure,(SIP)is used to simulate the discretized coupled algebraic equations.It has been observed that volume fraction of nano particles,ϕand magnetic field parameter,Ha are favourable for the heat transfer rate,however,both resist the fluid flow.Impact of applied uniform transverse magnetic field exceeds in the case of shear thickening fluids(i.e.n>1)by increasing the value of Ha as compared to that in shear thinning fluids(i.e.n<1).Therefore,enhancement in heat transfer rate is comparably more in shear thickening fluid.Furthermore,comparable limiting case study with published result is also carried out in this research paper.     

基于儒可夫斯基变换的涡轮钻具叶片设计及性能分析

为提高涡轮钻具叶片使用性能和创新叶片设计理论,提出了基于儒可夫斯基保角变换法与经典水力翼型相结合的涡轮钻具叶片设计新方法,以?127涡轮钻具叶片为研究对象,运用搭建的涡轮钻具叶型参数化设计平台和自主设计的涡轮钻具性能测试台架,完成了5种翼型的造型设计,研究了5种叶片流场性能,开展了设计叶片的性能测试实验,对比分析了设计叶片与塔里木油田某型在役?127涡轮叶片的实际效能。实验及仿真结果表明,基于新方法设计的NACA-0012翼型加厚叶片在600 r/min转速及15 L/s流量的设计工况下,其单级扭矩达5.83 N·m,较相同条件下某在役?127涡轮的单级扭矩提高约6.4%,级效率提高约1.16%,整体性能有了实质提升。     

新型“U”型板溶气气浮装置浓缩生化污泥的应用

介绍新型"U"型板溶气气浮装置以及"U"型板的工作原理,重点分析"U"型板溶气气浮对生化污泥的浓缩效果。在不同的污泥负荷、溶气回流比、PAC以及PAM加药量的情况下,进行气浮中试试验,寻找最佳的试验工况。试验结果表明,当污泥负荷为57 kg/(m^2·h)、溶气回流比为35%、PAC加药量为30 mg/L、PAM加药量为8 mg/L时,气浮出泥的污泥含固率能稳定在5.55%左右,"U"型板溶气气浮对生化污泥的浓缩效果很好。这对实际生产中气浮工艺取代二沉池以及重力浓缩池提供了现实可行的指导意义。     

Polymeric and non-crosslinked acid self-thickening agent based on hydrophobically associating water-soluble polymer during the acid rock reaction

Different from traditional crosslinked polymer diverting agents, a polymeric and non-crosslinked acid self-thickening agent (ZPAM) based on hydrophobically associating water-soluble polymer of acrylamide (AM), [2-(methacryloyloxy)ethyl]trimethylammonium chloride (DMC) and N,N′-dimethyl octadecyl allyl ammonium chloride (DOAC) was synthesized. The apparent viscosity variation of ZPAM acid solutions in acid rock reaction and rheological properties of ZPAM spent acid solutions were studied. Results showed that ZPAM acid solutions demonstrated good uninterruptedly thickening ability from low apparent viscosity to high apparent viscosity during the acid rock reaction. Meanwhile, ZPAM spent acid solutions showed good shear resistance, viscoelasticity and high temperature resistance. The thickening mechanism of ZPAM acid solutions during the acid rock reaction was explained by apparent viscosity change, rheological properties of simulative ZPAM acid solutions, and ZPAM aqueous solutions with different concentrations of CaCl₂. The results showed increasing calcium chloride concentration enhanced the hydrophobic association strength of the thickener solution, resulting in increasing solution viscosity, in other words, the self-thickening agent showed excellent salt resistance and acid resistance. In addition, the change of association strength of ZPAM acid solutions during the acid rock reaction was further confirmed via environmental scanning electron micrographs and UV spectrum. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47907.     

尾矿膏体形成机理浅析

针对某矿山铁尾矿物料特性,分析了尾矿膏体形成机理。结果表明,尾矿膏体的形成与尾矿性质、絮凝工艺、沉降高度、耙架搅拌等因素有关;该矿山尾矿可以采用单一浓缩方式直接制取尾矿膏体,也可以通过添加合适的固结材料来使其形成尾矿膏体。     

多功能润滑油添加剂聚甲基丙烯酸酯的研制

In this paper, four kinds of polymethacrylates(PMAs) used as multifunctional additives were synthesized from quaternary C1—C14 methacrylate, among which sample 4 exhibited relatively better performance. According to the methacrylate ratio of sample 4, the optimized reaction conditions of PMA were explored by orthogonal experiments comprising 4 factors and 3 levels, and the optimized reaction conditions covered an initiator dosage of 0.8 %, a molecular weight regulator dosage of 0.4%, a reaction temperature of 95 ℃ and a reaction time of 8.5 h. When the optimized PMA samples were used to formulate the 75W/90 automotive gear base oil, they exhibited improved shear stability and good low temperature property. In comparison with foreign commercial polymethacrylate GP, the optimized PMA samples exhibited better thickening ability, similar shear stability and slightly weak low temperature property, with their performance being the same as GP's on the whole. The slight difference in the performance between the optimized PMA and GP was attributed to the difference of chain length of copolymers and the distribution of relative molecular mass between them.