Works Of Cohesion Research Articles

Investigation of Asphaltene Polydispersity, Stability, and Deposition on Steel Using XDLVO Theory

The characterization and analysis of asphaltene particles are very crucial in the petroleum industry as the precipitation and subsequent deposition of asphaltenes cause formation damage and clogging of wellbore and production equipment, leading to production decline and operational drawbacks. In this study, the polydispersity of asphaltenes and the interaction between asphaltenes were probed by using the surface energy concept. Asphaltenes from three different oil fields in the Gulf of Mexico (GOM) were selected for this study. The results revealed that asphaltenes destabilized by different precipitants in the lab or from different assets in the field have distinctive surface energy values. Dispersive force was the dominant force of asphaltenes in oil systems. However, increasing polar forces appeared to increase the attractive interaction between asphaltenes which can in turn lead to higher aggregation and precipitation tendency. The magnitude of polar force is proportional to the content of heteroatoms and has a higher value for asphaltenes that were destabilized and then deposited by smaller alkanes. The stability of asphaltenes in oil from various fields and their deposition on steel were also investigated using the extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory. The results showed that van der Waals and acid–base interactions, among other components of the surface energy, were dominant in promoting asphaltene aggregation and deposition by increasing the attractive force between similar asphaltenes and asphaltene-steel, respectively. These findings were further supported by the concept of works of cohesion and adhesion. The results showed that asphaltenes were unstable and had the tendency to deposit on the steel substrate. The total interaction energy between asphaltene and steel, obtained from the XDLVO theory, and the work of adhesion correlated well with the amounts of asphaltene deposition generated by experimental lab setups. Interfacial tension between asphaltene and steel can provide information about the bond stability and deposit persistence under shear.

Surface free energies parameters in carbonate rock/nonacidic crude oil/brines systems

ABSTRACT Since knowing the effect of salt type is a vital parameter during smart-water injection for enhanced oil recovery (EOR) purposes, surface-free energies on the carbonate surface contacted by crude oil and different aqueous solutions with 0.7 ionic strength (about the ionic strength of seawater) are studied for solutions containing NaCl, Na2SO4, KCl, CaCl2, MgCl2, and MgSO4. For this purpose, the interfacial tension (IFT) of crude oil/aqueous solution and contact angle of oil/rock/brine are measured concomitant with the calculation of works of cohesion (WC) and adhesion (WA) as well as spreading coefficient (SC). Maximum equilibrium IFT reduction was observed for MgSO4 (from 22.7 to 12.71 mN.m−1). Besides, the calculated adsorption times using the exponential decay model reveal that the chloride salts of MgCl2 and KCl has the minimum and maximum adsorption time of 1600 s and 3400 s, respectively. Moreover, the contact angle measurements demonstrate that it is possible to change the wettability condition of rock surface from strongly oil-wet to strongly water-wet (about 20°) using Na2SO4 while the other utilized salts can change the contact angle from 170° to neutral wetness condition of 100°. The obtained results show that the best SC was obtained for DW due to its significant wettability alteration capability (from strongly oil-wet toward neutral state) compared with brine solutions. To sum up, according to the results it can be concluded that solution congaing MgSO4 can introduce the lowest IFT value and the highest wettability alteration from the initial strongly oil-wet state toward a neutral state, while Na2SO4 solution leading the lowest contact angle of about 20° which is the most favorable condition (strongly water-wet).

On the Institutional Theory of Money: Learning from J. R. Commons’ Institutional Economics

:I collect and organize the essential elements of ITM (institutional theory of money) from Commons’ Institutional Economics (1934) and compare them with STM (sovereign theory of money), to make the book more accessible for Japanese researchers. After introduction, I examine how money is treated in Commons’ analysis of Capitalism. Then I examine Commons’ critical interpretation of Knapp's work, and compare ITM with STM (or Hypothesis of “debt of life”). Finally I consider two research theme related to ITM. The conclusions obtained from the above are as follows: (1) Commons inherited the basic idea of ITM (the whole of “releasable debts” and payment-means should be treated as an institution), from Knapp. Commons’ originality consists in his consideration of the historical variability of debts, and in his relativization of Knapp's “state theory” relative to selection of means of private payment. (2) Commons gives detailed explanation to the sequential structure (i.e., power—authority—sovereignty—believes and needs) that supports stability of the money as an institution. (3) In STM's works of social cohesion, study of debts is expanded to non-western and non-modern societies, and central bank moneys in our times. So I find such ITM genealogy as Knapp-Commons-STM.

Gypsum-brine-dolomite interfacial interactions in the presence of scale inhibitor

The underlying mechanisms upon which chemical scale inhibitors (SIs) mitigate inorganic scale formation, as a major drawback of waterflooding, are of practical implications. The present study investigates interactions between gypsum precursors in contact with dolomite rock and brine from experimental, simulation, and theoretical stands point of view. The influence of various dominant parameters such as the presence of inhibitor, dolomite rock and brine salinity on the intermolecular interaction energies is investigated. The results show that with the use of SI, the electrical double-layer and Lewis acid-base interaction energies decrease whereas Lifshitz-van der Waals increases approximately one order of magnitude. Furthermore, based on the works of cohesion and adhesion, the used SI retards gypsum from getting precipitated then deposited almost 77% and 90%, respectively. In most cases also, the gypsum-scaled dolomite rock compared to the bare rock would be more prone to gypsum scaling.

Determining the Surface Properties of Carbon Fiber in Contact Interaction with Polymeric Binders

Application of various criteria for evaluating the wettability of the surface of carbon fibers of Torayca T 300 3K brand was considered. A simulation of the carbon fiber impregnation in fabrication of a composite material was used to determine the thermodynamic parameters (surface energy, works of adhesion and cohesion) and the wetting angle for three kinds of promising polymeric binders. It was found that the best impregnation conditions for carbon fiber of Torayca T 300 3K brand (Cm12073 fabric) will be for the filament not subjected to thermal treatment because the capillary rise of the organic solvent simulating the polymeric binder decreases by 14% on removing the finishing oil. The presence of the Infutac layer fixer used to fabricate reflector segments raises the time of penetration of the polyurethane (with shape memory) and epoxy binders into the fabric sheet, makes the impregnation six times lower, and has no effect on the time of impregnation of carbon fibers with the silicone binder.

How Glycerol and Water Contents Affect the Structural and Functional Properties of Starch-Based Edible Films

As starch is an inexpensive, filmogenic, easily processable and a widely available material, it is a material that can be utilized in the creation of biodegradable films and containers, presenting as a viable alternative to polymers derived from petrol. Moreover, starch could also be used to create edible coatings for fresh foods in order to extend shelf life. As such, wheat starch films with two glycerol contents were formulated to mimic the effects of compounds currently used to coat fruit. Their structural and functional properties were characterized. This study found that the transfer properties of starch films containing 33% of plasticizer was less effective than film comprised of 50% glycerol. Water diffusivity, oxygen permeability, and water vapor permeability at two different humidity gradients, surface tension, works of surface adhesion and cohesion, and moisture sorption were tested. Glycerol content does not play a significant role on the color or mechanical properties. This work shows that glycerol can strongly affect the functional properties of starch-based coatings and films.

Investigating injection of low salinity brine in carbonate rock with the assist of works of cohesion and adhesion and spreading coefficient calculations

Low salinity (LS) and smart water (SW) flooding processes which receive a great interest as cost-effective and environmental friendly techniques are relatively new enhanced oil recovery methods. Although shifting carbonate surfaces towards a water-wet state is the main mechanism behind these methods, effects of controlling factors (for instance: ion type or salinity) are already remained unsettled. In this regard, the effects of sulfate ion types (i.e. Na2SO4, MgSO4 and CaSO4) and their concentrations (i.e. 0–45,000 ppm) on wettability alteration are investigated using contact angle (CA) measurement technique. In addition, work of cohesion, work of adhesion and spreading coefficient of all examined salts are calculated based on the experimental interfacial tension (IFT) and CA measurements. The results reveal that reduction of salinity of the aqueous solution and presence of sulfate anion at high salinity conditions (15,000–45000 ppm) are two important parameters for wettability alteration.

Investigation of the influence of organomineral additives on the colloid-chemical properties of geocement dispersion

The object of research is the geocement dispersion of the heulandite-clinoptilolite composition of the structural formula Na 2 O × Al 2 O 3 × 6SiO 2 × 20H 2 O, modified with an organomineral additive The results of the effect of an organomineral additive on the colloidal-chemical properties of geocement dispersion are presented. Mathematical models that characterize the effect of the concentrations of constituent organomineral additives on changes in its basic physical and colloidal chemical properties are obtained: – conventional viscosity; – density; – wetting angle; – surface tension; – works of adhesion, cohesion and wetting of geocement dispersions, factors X1 ... X3 have an influence that are significant. Also, the joint effect of factors, respectively, x1x2x3, x1x2, x1x2 and x1x3 has a significant effect. The coefficients of wetting and spreading of geocement dispersions are significantly influenced only by the joint action of the factors x1x2x3. Relationship is established between the conditional viscosity and the wetting coefficient, between the wetting angle, adhesion, wetting and spreading work and between the density, surface tension and work of cohesion. The composition of the organomineral additive is optimized and the areas of permissible concentrations of its constituents are determined: – along the X1 axis, 2–2.3 % of polymer RI-551Z; – along the X2 axis, 2.1–2.5 % of microcalcite; – along the X3 axis, 4.5–6.5 % of aluminate cement, which, when introduced into a geocement dispersion, allows Na 2 O × Al 2 O 3 × 6SiO 2 × 20H 2 O to stabilize its colloidal-chemical properties. It is determined that the changes in the values of the other output parameters are tied to the change: – the conditional viscosity and their values are in the following limits: r =1.571–1.766 g/cm 3 , cos Q =0.50–0.67; – surface tension s =114–128 mN/m; – works of adhesion, wetting and cohesion, respectively, 184–204 mN/m; – coefficients of wetting and spreading -0.77–(-)0.84, -37–(-)55 mN/m.

Transfer printing methods for the fabrication of flexible organic electronics

A transfer printing method for fabricating organic electronics onto flexible substrates has been developed. The method relies primarily on differential adhesion for the transfer of a printable layer from a transfer substrate to a device substrate. The works of adhesion and cohesion for successful printing are discussed and developed for a model organic thin-film transistor device consisting of a polyethylene terephthalate (PET) substrate, gold (Au) gate and source/drain electrodes, a polymethylmethacrylate (PMMA) [or poly(4-vinylphenol)] dielectric layer, and a pentacene (Pn) organic semiconductor layer. The device components are sequentially printed onto the PET device substrate with no mixed processing steps performed on the device substrate. Optimum printing conditions for the Pn layer were determined to be 600psi and 120°C for 3min. A set of devices with a PMMA dielectric layer was measured as a function of channel length and exhibited a contact resistance corrected mobility of 0.237cm2∕Vs. This is larger than the mobility measured for a control device consisting of Pn thermally deposited onto the thermally oxidized surface of a silicon substrate (SiO2∕Si) with e-beam deposited Au top source/drain contacts. The structure of transfer printed Pn films was also investigated using x-ray diffraction. The basal spacing correlation length for a 50nm Pn film printed at 600psi and 120°C for 3min onto a PMMA surface showed a 35% increase as compared to an unprinted film on a thermally oxidized silicon substrate. The crystalline size was seen to correlate with the mobility as a function of printing conditions.

A new understanding on the mechanism of fountain solution in the prevention of ink transfer to the non-image area in conventional offset lithography

In conventional offset lithographic printing, it has been well established that the existence of a continuous layer of fountain solution (FS) on the surface of the non-image area is an essential condition to ensure correct operation of lithography. However, the mechanistic function of FS in preventing the ink from being transferred onto the non-image area has not been fully understood. Several major mechanistic interpretations can be found in the literature, which are based either on comparing of static works of adhesion and cohesion of ink and FS, or on the splitting of the 'weaker' FS layer. Although the latter becomes more accepted, direct experimental evidence is difficult to find in the literature. On the other hand, confusing information found in the literature showed that the ink-transfer (or non-transfer) observations reported in many case studies correlate well with simple comparisons of works of adhesion, cohesion and spreading data of ink/FS, ink/plate and FS/plate obtained under the static condition. These results, therefore, imply that, in explaining the function of FS in preventing ink transfer to the non-image area, the ink/FS interfacial adhesion failure would be the dominant mechanism. The work presented in this study covered two specific areas in order to address and better understand the responses of ink and FS layers and their interface to forces encountered during ink transfer. Firstly, an analysis of lithographic plates contaminated with a cationic polymer revealed that the violation of the ink non-transfer condition of the plate non-image area due to contamination could be predicted by traditional criteria of plate wetting and works of adhesion and cohesion. However, these traditional criteria cannot reliably predict the non-transfer condition of the ink on the clean non-image area that was covered by FS. Secondly, in some novel experiments conducted in this study using ice or Teflon as a substrate, the works of adhesion and cohesion were not able to predict ink transfer in most cases. Direct experimental evidence from this work revealed that splitting of the FS layer was involved in the prevention of ink transfer to the non-image areas, and that the thickness of the FS layer was critical in allowing the splitting to occur.

A relationship between surface free energy and polarity data and some physical properties of spheroids

Spherical particles have been produced by extrusion and spheronisation of a wet mass of lactose, microcrystalline cellulose and indomethacin (as a model drug), and of mixtures of microcrystalline cellulose, barium sulphate and glyceryl monostearate (to test the general applicability of the surface energy predictions). The surface energies of the powders were estimated from contact angle measurements. The work of cohesion of each powder, and the work of adhesion between pairs of powders were assessed, as were spreading coefficients of the powders over each other. It was found that the spheres produced without indomethacin (lactose and microcrystalline cellulose only) required a significantly higher force to cause crushing, and were also of higher density than any of the four batches which contained different levels of indomethacin. The batches with added indomethacin had similar physical properties irrespective of indomethacin loading. Spheroids containing glyceryl monostearate and barium sulphate had much higher porosities and lower crushing strengths than the indomethacin based formulations. These differences are explained in terms of much lower works of adhesion and cohesion for barium sulphate and glyceryl monostearate than were obtained for the other materials. The differences in the properties of the spheroids have been explained in terms of interfacial phenomena, and in particular the relative works of adhesion between the solids.

Binder-substrate interactions in wet granulation. 1 : The effect of binder characteristics

A laboratory-scale, instrumented mixer torque rheometer has been used to examine the interactions of microcrystalline cellulose with aqueous solutions of two polymer binders. The rheological behaviour indicated differences, at equivalent viscosity, between the two polymers, which were explained by theories relating binder surface tension to granule properties. The measured surface tension values were then used to calculate the surface free energies, interfacial works of cohesion and adhesion and spreading coefficients for the interaction between the materials used in this study. These data indicated a different degree of interaction between the two polymers and the cellulose substrate, which was probed further using a series of experiments to examine polymer adsorption phenomena. These combined data were used to propose a pattern of behaviour based on consideration of ‘intra-granular viscosity’ which helped to explain the observed rheological behaviour.

Correlation between predicted binder spreading coefficients and measured granule and tablet properties in the granulation of paracetamol

The interfacial works of cohesion, adhesion, interaction parameters and spreading coefficients have been calculated for paracetamol granulated with hydroxypropyl methylcellulose, acacia, polyvinyl pyrrolidone and starch using literature values of surface free energies. In general, the predictions made regarding film formation, granule morphology and failure processes are consistent with literature data. Correlations have been found between the spreading coefficient of the binder over the substrate and actual experimental measurements of granule friability, tablet strength and tablet capping. The shape and complexity of the relationships can be further explained on the basis of the relative changes in binder cohesion.

Polar/non-polar interactions in the granulation of organic substrates with polymer binding agents

Calculations of the thermodynamic works of cohesion and adhesion (between substrate and polymer binder) based on a knowledge of either the partial cohesion/solubility parameters or surface free energies of the constituents have shown that there is a parabolic relationship between the reduced spreading coefficient (defined as the ratio of the work of adhesion to the work of cohesion) and the fractional polarity of the substrate. The relationship is independent of the method used to calculate these two dimensionless parameters but is specific for each polymer binder. It is possible, using the relationship, to explain the apparently anomalous results in the literature regarding the rank ordering of polymer binders and to predict the optimum binder for any particular substrate.

Surface free energy and polarity effects in the granulation of a model system

The interfacial works of cohesion and adhesion, the interaction parameter and the spreading coefficients of one phase on the other have been calculated for a model system consisting of untreated and surface-treated glass granulated with a number of polymeric binders using literature values of surface free energies. In general the predictions made regarding film formation, granule morphology, failure processes and granule strength are consistent with literature data.

Binder-substrate interactions in granulation: a theoretical approach based on surface free energy and polarity

The interfacial works of cohesion and adhesion (between substrate and binder) in addition to the spreading coefficients of one phase on the other have been calculated for a number of pharmaceutical solids and polymeric binders using literature values of surface free energies and polarities. For low polarity substrates (polarity < 0.2) calculations have shown that polyvinyl pyrrolidone or starch would be the optimum binder while for higher polarity substrates (polarity > 0.4) the cellulose derivatives or acacia would be the optimum binder, consistent with the trends reported in the literature. The spreading coefficients have implications in that it is possible to hypothesise two distinct modes of granule formation.

A model for the genetic control of differential adhesion in insect epidermis

Adhesive relations among cells are believed to play a major role in determining patterns of serial homology, of intercalary regeneration, and of neuronal connectivity. Models for the genetic control of adhesion during development can provide a framework for further analysis of these phenomena. Investigators studying development of Drosophila have proposed that differentiation of segments and of imaginal discs is controlled by a set of bistable “selector genes”. In each region the settings of the selector genes form a binary “word” which determines the properties of cells in the region, including their adhesiveness. I have made an explicit proposal for the relation between binary words and adhesiveness, by assuming that active selector genes repress synthesis of “adhesor” macromolecules, which promote adhesion. This hypothesis correctly predicts the relative cohesiveness of cells in four pupal tissues of the moth Manduca. Works of cohesion and adhesion among the four cell types are deduced from published results of grafting experiments by modelling insect epidermis as a viscoelastic fluid. Further comparisons between deductions from the genetic and fluid models suggest that selector genes, or the adhesor molecules they regulate, interact within single cells in determining adhesiveness between cells. From a specific version of the genetic model I deduce that pairwise interactions between selector genes or adhesor molecules can determine many, though not all, of the relative works of adhesion between unlike cells in Manduca. The genetic and fluid models thus provide a set of working hypotheses for predicting patterns of intercellular adhesion in insect epidermis and for analyzing results of experiments designed to test such predictions.

Contact angles in controlled atmospheres: Some theoretical considerations

Contact angle measurements in controlled atmospheres must take into account the effect of residual gas molecules in the less-than-perfect vacuum that is encountered experimentally and of the gas molecules formed by vaporization of the liquid component. The possibility of measuring the contact angle of a non-vaporizing liquid has been considered. In an experiment with a low-melting lead bismuth alloy on glass, the contact angle at 142°C was 136°. Calculations based on the Fowkes theory of dispersion forces indicate that the contact angle should not exceed 141°. In contrast to the reasonable agreement with the Fowkes theory, the observed angle is lower than would be expected from the Yarnold-Mason theory as it would apply to a competition between residual gas molecules and metal atoms for the solid surface and the effect of this competition on the contact angle. Finally, the theory of works of adhesion and cohesion is applied to the known variability of the hydrophilicity of graphite surfaces. The known reactivity of adsorbed water with graphite makes it impossible to apply an exact theory, but a limiting value of 53 % hydrophilic surface is indicated for graphite at room temperature. Limits of contact angles of 0° are indicated by the physical meaning of contact angle. If one considers surface energies only, the limits must be placed at 0° (and γ lv cos θ = γ LV) and 180°. However, considerations based on dispersion forces indicate that γ LV cos θ > γ LV should be observable experimentally and contact angles approaching 180° should be impossible of physical existence at equilibrium.