On bitumen liberation from oil sands

Laboratory experiments were performed to investigate the effect of pH on (a) bitumen film thinning and film rupture process (b) bitumen/water contact line displacement and (c) the static contact angle of bitumen on a glass surface in the presence of an aqueous medium. A coated bitumen film on a glass surface was found to thin down and rupture spontaneously when a few drops of water having a pH of 11 was placed on it. In another experiment, a bitumen coated glass plate was submerged in water. The contact line of an initially circular bitumen film on the glass surface displaced in the inward direction to take the shape of a droplet. Measurement of the dynamic contact angle of bitumen with time showed that the bitumen/water contact line displacement was faster at a pH of 3 than at a pH of 11. However, the static contact angle of bitumen on the glass surface was found to be large at the high pH of 11, a condition conducive to easy detachment of bitumen droplet from the glass surface. The above observations suggest that a pH cycle might be desirable in bitumen liberation from oil sands.     

Spontaneous spreading of emulsions on solid surfaces: Morphology and dynamics

The spontaneous spreading of emulsions of water dispersed in silicone oil onto glass surfaces is examined using differential interference contrast (DIC) microscopy. Spreading occurs via a precursor film from which the emulsion droplets are excluded. The radius of the interline of the bulk drop is found to vary as (time)^1/10, as is commonly observed for the spontaneous spreading of pure liquids. The spreading rate constant decreases linearly with the volume percent of the dispersed phase, but drops suddenly to zero at approximately 73% dispersed phase. The width and spreading rate of the precursor film also is found to decrease with dispersed phase concentration. A fingering type of instability is evident at the leading edge of the precursor film, yet has little effect on the spreading rate of either the precursor film or the droplet interline. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1817–1825, 2001     

EFFECTS OF MASS TRANSFER ON THE THINNING AND RUPTURE OF A PLANE PARALLEL LIQUID FILM

The effects of mass transfer and physical properties upon the thinning and rupture of adraining plane parallel film are investigated.An equation is derived in which the thinning rate is afunction of bulk properties.surface properties(surface tension,surface viscosities,and the variationof surface tension with surface concentration),intermolecular forces(London-van der Waals forcesand electrostatic double layer forces),adsorption and surface diffusion coefficients,bubble size andfilm thickness.An estimation for the critical thickness at which a film rupture is carried out and thecoalescence time is obtained by integration to the critical thickness,The coalescence time is predictedas a function of bulk and surface properties,London-van der forces,adsorption and surfacediffusion coefficients,and bubble size.     

Characterization of an amorphous surface layer on blown polyolefin film

This study concerned an amorphous surface layer on blown polyethylene film with a composition different from that of the bulk. The surface layer was characterized by gentle probing with an atomic force microscope. The demonstration of an amorphous layer uniformly covering the surface of a blown Ziegler–Natta‐catalyzed polyethylene (znPE) film reproduced previous reports. Removing the surface layer by solvent washing confirmed the hypothesis that the layer consisted of lower molecular weight, higher branch content fractions. A blown film of znPE blended with up to 30 wt % impact‐modified high‐melt‐strength polypropylene (hmsPP) also exhibited an amorphous surface layer. In thin films, it was advantageous for the mobile, amorphous fractions of ethylene–propylene rubber (EPR) to locate at the surface rather than at the phase interface. The amorphous EPR tended to segregate into pools on the film surface, and this pointed to a substantial difference between the amorphous surface layers on the znPE and hmsPP/znPE blend films. Surface enrichment best described the compositional gradient that resulted from the concentration of lower molecular weight, higher branch content chains at the surface of the znPE film. Surface segregation was more appropriate for the emergence of EPR fractions as a separate phase on the surface of the hmsPP blend film. Films blown from a blend of a Ziegler–Natta‐catalyzed polyethylene and a metallocene‐catalyzed polyethylene (zn/mPE) and its blend with hmsPP reproduced the primary features of surface enrichment and surface segregation. Some differences between the znPE and zn/mPE films were attributed to the metallocene constituent of zn/mPE. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3625–3635, 2002     

Bulk surface photografting process and its applications. I. Reactions and kinetics

A bulk surface photografting process which is conducted in the interface between two polymer films was designed and investigated. The bulk surface photografting is a highly efficient process. With this method, the surface of hydrophobic polymers can be made hydrophilic in less than 2 s and a grafted layer 5 μm thick can be obtained in 30 s. The kinetic investigation shows that the bulk surface photografting polymerization involves a four-step reaction process: induction period, surface initiation, successive polymerization, involves a four-step reaction process: induction period, surface initiation, successive polymerization, and solid-phase crosslinking. The photoreduction of benzophenone (BP) takes place in the interlayer between the LDPE films and is a three-stage process: surface photoreduction, secondary photoreduction, and solid-state photoreduction. With regard to the photoreduction of the initiator caused by hydrogen abstraction, the kinetic studies show that the photoreduction rate has a first-order dependence on the BP concentration. The activation energy of the hydrogen abstraction reaction is about 28.5 KJ (6.8 kcal)/mol. With regard to the photografting polymerization reaction, the reaction order of the rate Rp with respect to the monomer is unity and 0.89 with respect to BP. This means that the termination reaction takes place mainly by combination of polymer chain free radicals and semipinacol free radicals from BP. The activation energy of the overall polymerization reaction is around 8.8 kJ (2.1 kcal)/mol. © 1996 John Wiley & Sons, Inc.     

Structure and thermal molecular motion at surface of semi-crystalline isotactic polypropylene films

Surface crystalline structure in isotactic polypropylene (iPP) films was explored by in-plane grazing incidence X-ray diffraction measurement. Apparent crystallinity in the surface region was lower than the bulk one. After an etching treatment with a droplet of potassium permanganate solution, a clear crater was formed at the surface, and the step height between etched and intact regions was approximately 3 nm. This means that the iPP surface was covered with 3 nm thick amorphous layer. Then, surface molecular motion in the iPP films was examined by lateral force microscopy. Surface α_a-relaxation process arisen from the segmental motion was observed at about 250 K, and its apparent activation energy was 230±10 kJ mol⁻¹. The both were lower than the corresponding bulk values, indicating that surface molecular motion is more active than the bulk one even in the semi-crystalline iPP films. An iPP film with 1.5 nm thick surface amorphous layer was prepared. In this case, the enhanced mobility was still observed at the surface, but the extent of the enhancement was not remarkable as that for the iPP film with 3 nm thick surface amorphous layer. These results imply that surface mobility is affected by the presence of underneath crystalline phase, if the surface amorphous layer is thin enough.     

Activation energies for crystallization of manganese-doped (K,Na)NbO3 thin films deposited from a chemical solution

Potassium sodium niobate (KNN) thin films are potentially useful for energy harvesting devices and for lead-free piezoelectric microelectromechanical systems. This work reports the activation energies for nucleation, growth and perovskite phase transformation from a 0.5% manganese-doped KNN 2-methoxyethanol-based solution modified with acetylacetone and excess alkali precursors. The films were annealed in a rapid thermal processor (RTP) with a hold step at temperatures from 500 to 550°C. The activation energies for perovskite transformation and growth, determined by electron micrograph observation, were 687 ± 13 and 194 ± 10 kJ/mol. The activation energy for nucleation was 341 ± 20 kJ/mol. Based on these data, crystallization in KNN is found to be nucleation-limited; thus, it should be possible to reduce the crystallization temperature by utilizing a seed layer which provides nucleation sites, provided the organics are removed from the film.     

含气泡油滴撞击矩形沟槽壁面的数值分析

采用耦合水平集-体积分数（CLSVOF）方法对含气泡油滴撞击矩形沟槽壁面现象进行数值模拟研究,考察了油滴撞击壁面后的形态演化过程,分析了中心射流形成机理和气体夹带的分布规律,并探究了沟槽宽度、沟槽深度和撞击位置对油滴铺展特性的影响。研究表明：含气泡油滴在矩形沟槽壁面铺展时会形成中心射流,沟槽内部存在气体夹带现象。气泡底部的速度旋涡是形成中心射流的主要原因,沟槽内的气体夹带受油滴铺展速度影响呈现规律性分布。沟槽宽度对含气泡油滴在垂直沟槽方向和平行沟槽方向的铺展长度影响较大,但对铺展高度影响较小。当无量纲沟槽宽度为0.3时,油滴形成颈部射流并在运动后期使垂直沟槽方向的铺展长度迅速增加。此外,沟槽深度也对含气泡油滴在各方向的铺展有重要影响,沟槽深度越大,中心射流现象越难形成。撞击位置变化不改变油滴在沟槽壁面上的运动演化过程,但对沟槽内部的气体夹带规律有一定影响。     

Formation and characterization of perfluorocyclobutyl polymer thin films

Perfluorocyclobutyl (PFCB) polymers are a new class of materials that show promise as selective layer materials in the development of composite membranes for gas separations, such as carbon dioxide/methane (α_{pure gas} = 38.6) and oxygen/nitrogen (α_{pure gas} = 4.8) separations. In many of the flat sheet applications, a thin film of the selective layer that is free of major defects must be coated onto a support membrane. A focus of this study was to elucidate the impacts of solvents, polymer concentration, and dip‐coating withdrawal speed on PFCB thin film thickness and uniformity. An extension was proposed to the Landau–Levich model to estimate the polymer film thickness. The results show that the extended model fits the thickness‐withdrawal speed data well above about 55 mm/min, but, at lower withdrawal speeds, the data deviated from the model. This deviation could be explained by the phenomenon of polymer surface excess. Static surface excesses of polymer solutions were estimated by applying the Gibbs adsorption equation using measured surface tension data. Prepared films were characterized by ellipsometry. Refractive index was found to increase with decreasing film thickness below about 50 nm, indicating densification of ultrathin films prepared from PFCB solutions below the overlap concentration. Atomic force microscopy was used to characterize surface morphologies. Films prepared from tetrahydrofuran and chloroform yielded uniform nanolayers. However, films prepared using acetone as solvent yielded a partial dewetting pattern, which could be explained by a surface depletion layer of pure solvent between the bulk PFCB/acetone solution and the substrate. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Oil Sand Slurry Conditioning Tests in a 100 mm Pipeline Loop

Fresh oil sand slurries were prepared and tested in a 100 mm pipeline loop at 37°C to evaluate the effects of average flow velocity, slurry air content and air injection method (bulk or continuous) on slurry conditioning, i.e., the evolution of the in‐pipe processes that promote gravity separation of bitumen‐air aggregates from the remainder of the slurry. The potential separability of the bitumen in the slurry was evaluated using a slurry Conditioning Index (CI). When no air was injected into the slurry, the slurry CI was low (≤0.1), indicating very poor conditioning. An increase in flow velocity from 2 m/s to 4 m/s and injection of 5% air (by volume) dramatically improved the slurry CI, to ～ 0.6. The improved slurry conditioning observed at the higher velocity is explained by the increased force of fluid turbulence experienced by the particles and the greatly enhanced bitumen‐air contact.     

Direct Measurement of Fusion Enthalpy of LaAlO3 and Comparison of Energetics of Melt,Glass, and Amorphous Thin Films

Enthalpy of fusion and melting temperature of perovskite LaAlO₃ were measured using thermal analysis method as 124 ± 10 kJ/mol at 2134 ± 10°C, providing a value of 52 ± 4 J·(mol·K)^?1 for entropy of fusion. Crystallization enthalpy of amorphous LaAlO₃ thin films was found to change from ?24 to ?17 kJ/mol with decrease in film thickness from 100 to 20 nm. Differences in energetics of amorphous LaAlO₃ films and glass cannot be explained exclusively by surface energy contribution but must reflect differences in structure between films and glasses in this system.     

连续离子层吸附反应(SILAR)法制备纳米Cu_2O薄膜

采用低温液相薄膜制备工艺--连续离子层吸附反应(SILAR)法,在玻璃衬底上制备了纳米Cu2O薄膜,考察了工艺参数对薄膜质量和薄膜表面形貌的影响,对薄膜的生长速率与反应溶液浓度、反应温度以及循环次数的关系进行了研究和分析。结果表明,采用连续离子层吸附反应(SILAR)法有利于制备高质量的纳米Cu2O薄膜,连续离子层吸附反应(SILAR)法可以有效去掉疏松的离子,每次循环吸附反应都能使紧密吸附的离子转化成致密的纳米Cu2O薄膜,这样既有利于纳米Cu2O颗粒的生成,同时减少了污染和降低了成本。试验表明,制备纳米Cu2O薄膜的最佳反应温度为70℃,最佳反应溶液浓度均为1 mol/L,纳米Cu2O薄膜的膜厚随着循环次数的增加而增加,循环40次可制得厚度为0.38μm的薄膜。经XRD和SEM测试,所制备的薄膜纯度高,表面平整且致密,Cu2O颗粒大小约为100 nm。     

Survey of heat transfer mechanisms in a slurry bubble column

Heat transfer mechanisms in the bulk and distributor regions of a slurry bubble column are investigated based on the measurements of local heat transfer in a 0.28 m diameter Plexiglas column. The gas, liquid and solid phases used are oil‐free compressed air, tap water and 35 μm glass beads. The slurry concentration and superficial gas velocity are varied from 0 to 40 vol% and 0.05 to 0.30 m/s respectively. Measurements have been made with a fast response heat flux probe which provided local instantaneous heat transfer coefficients. The time‐averaged heat transfer coefficients in the bulk region were on average about 50% higher than the distributor region of the column. The wall region heat transfer coefficients are well predicted by the correlation of Deckwer et al. (1980). Heat transfer mechanism in column centre can be adequately described by the consecutive film and surface renewal model.     

池沸腾下朝向曲面加热面临界热通量分析模型

堆内熔融物滞留（IVR）策略得以实施的关键在于压力容器下封头外部冷却（ERVC）能力,即压力容器下封头外部临界热通量（CHF）高于下封头壁面对应的热通量。通过结合Helmholtz不稳定性与液膜蒸发,提出了池沸腾下朝向曲面加热面临界热通量的分析模型。由于表面张力作用,内部嵌有汽柱的薄液膜附着在下封头壁面外,Helmholtz 不稳定性作用于薄液膜与汽柱的交界面;随着加热表面热通量的增大,汽柱与液膜之间相对速度达到一定时,在Helmholtz 不稳定性的作用下,汽液交界面产生畸变,并形成汽膜,阻碍主流液到达加热表面;当加热热通量接近CHF时,液膜逐渐蒸发直至CHF触发。通过该模型计算得到了不同过冷度下,CHF随加热曲面方位角的变化,计算结果与现有的大量实验数据一致性较好。     

Reduction of SiO2 by Molten Al

The bulk reaction of Al and SiO₂ was reexamined in light of results of thin-film work. When the bulk reaction was conducted under vacuum in such a way that the oxide film on the Al was almost completely absent, the reaction started immediately and proceeded at a rate more rapid than that observed by previous workers, who conducted the experiment in air at atmospheric pressure. Results obtained at 700° to 820°C indicate that the activation energy for the reaction is 42±5 kcal/mol when oxide films are absent from the surface of the molten Al.     

地质体中沉积有机质的模拟生烃动力学研究

采用热解方法对地质体中沉积有机质——源岩干酪根和固体沥青进行了生烃动力学研究,建立了平行一级反应动力学模型,求取了动力学参数活化能E和指数前因子A,主要反应的活化能集中在170—210kJ／mol的范围内。反映了干酪根和沥青是一个大分子网络体系,其热解过程涉及不同能级化学键的断裂。实验所得到的沉积有机质热解动力学参数,可用于样品母质类型判别和成熟度确定。     

DLVO AND NON-DLVO FORCES IN THIN LIQUID FILMS FROM RHAMNOLIPIDS

Microscopic foam films (r?=?100?μm) stabilized with a single rhamnolipid with a well-known structure (α-L-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoate (R1)) are investigated, and the obtained results are compared with results obtained from studies of foam films formed from solutions of rhamnolipid mixtures. The studies are carried out employing the Scheludko-Exerowa microinterferometric method. The dependence of foam film thickness on the electrolyte concentration (C _el ) of the solution is monitored, and formation of common films (CF), common black films (CBF) and Newton black films (NBF) is found. The continuous CBF-to-NBF transition is considered as evidence of the action of repulsive forces that are not described by the classic Derjaguin–Landau–Verwey–Overbeek (DLVO) theory of colloid stability. These non-DLVO repulsive forces lead to an additional positive component of the disjoining pressure. To understand better the surface forces operating in the rhamnolipid foam films, direct measurements of the disjoining pressure/film thickness (Π(h)) isotherms are carried out employing the thin liquid film–pressure balance technique. The comparison of the obtained experimental Π(h) isotherm for CF (C _el ?=?10^?3 mol dm^?3 NaCl) to the DLVO theoretical predictions yields a diffuse electric layer potential of?～?5?mV and surface charge density of?～?50?mC?m^?2 at the film solution–air interfaces. The deviation of the experimental curve from the theoretical one found for films thinner than about 40?nm evidences the action of non-DLVO surface forces. The experimental steplike Π(h) isotherms obtained for the CBF (C _el ?=?0.15?mol?dm^?3 NaCl) are considered to result from an aggregation process, leading to the formation of lamellar structures in the foam film. The obtained results show that the surface forces operative in rhamnolipid foam films are determined not only by the structure and organization of the adsorbed layers but also by the molecular state of the bulk solution.     

Effect of deposition temperature on the growth of Y1Ba2Cu3O7−x thin film by aerosol assisted chemical vapor deposition using liquid solution sources

We have investigated the effect of the deposition temperature on the growth of Y₁Ba₂Cu₃O_7−x (YBCO) thin film using liquid solution sources on MgO (100) single crystalline substrate and have characterized the superconducting properties. The YBCO films were prepared by aerosol assisted chemical vapor deposition (AACVD). Single solution source of Y, Ba, and Cu β-diketonates dissolved in tetrahydrofuran (THF) was used as precursor. This precursor was passed through an ultrasonic aerosol generator and transported into a hot-wall CVD reactor using Ar as reactant gas (400 secm). The substrate was placed normal to the gas stream and the substrate temperature was varied from 760 to 860 °C. Deposition was carried out in oxygen atmosphere maintaining total pressure of 3.2 Torr inside the chamber. Deposition time was also varied from 10 to 30 min. The grown YBCO thin films were highly oriented to (001) orientation perpendicular to the substrate. The film deposited at 815 °C had a sharp transition to superconducting state about 87 K. The activation energy estimated from the Arrhenius plot is ∼19.14 kJ/mol at the deposition temperature of 815 °C.     

Calcium Segregation to a Magnesium Oxide (100) Surface

The segregation of calcium to a (100) cleavage surface of an MgO crystal, with bulk calcium concentration of 200 ppm was measured in situ at T =900° to 1450°C in ultrahigh vacuum, using Auger and low-energy ion-scattering spectroscopies. A measured heat of segregation of approximately -50.3 kJ/mol (-12 kcal/mol) is in favorable agreement with a value of -58.7 kJ/mol (-14 kcal/mol) determined using solute strain energy and surface free energy criteria. The equilibrium value for the calcium segregation between 950° and 1000°C is estimated to correspond to a 20% occupation of the surface cation sites.     

Alignment layer relaxation—a technique for assessing thermal transitions in polymer films

We introduce a method for assessing the glass transition temperature (T_g) of thin polymer films. The technique may be applied to any polymer film that can effect liquid crystal alignment, and is demonstrated here for a commercial polyamide-imide. The method leverages the ability of the polymer film to align nematic liquid crystals on its surface, when that surface has been prepared by mechanical brushing. Relaxation of the alignment layer, brought about by thermal cycling through T_g, is seen to affect liquid crystal alignment, and thus serve as a T_g indicator. The technique reveals a three-order-of-magnitude change in the measured property. The method allows the assessment of that portion of the film responsible for aligning liquid crystals, and provides an indication of the efficacy of alignment. Our results imply that the relaxation of the surface in Probimide 32 occurs over a range of temperatures, and relaxation is not complete until the film is heated to a temperature above the glass transition of the bulk polymer.