Appearance Of Polymers Research Articles

Study on the channeling limit of polymer flooding in the conglomerate reservoir

The conglomerate reservoirs are known for their high degree of heterogeneity, which poses a challenge during polymer injection. Fluids tend to channel along dominant paths leading to premature appearance of polymer in the oil well. This phenomenon results in a rapid increase in water cut, leading to wastage of the polymer. Currently, there is no reliable method for identifying polymer channeling in such conglomerate reservoirs. To address this issue, this paper conducts physical simulation experiments on parallel cores under varying heterogeneous conditions based on the geological characteristics of the reservoir. The study analyzed and statistically evaluated the distribution ratio, water cut, and polymer concentration in the output under varying heterogeneous conditions. This analysis identified the distribution ratio and polymer concentration as key indicators of polymer channeling. Based on these findings, a comprehensive discriminant diagram of polymer channeling was established. The study found that the coefficient of permeability variation (CV) was the primary factor contributing to channeling. This diagram can be used to understand the underlying principles of polymer channeling and provide technical guidance for developing effective profile control schemes and optimizing site construction strategies.

Insight into poly(1,3-dioxolane)-based polymer electrolytes and their interfaces with lithium Metal: Effect of electrolyte compositions

The transport properties and electrochemical stability of advanced lithiummetal batteries are severely constrained by the actual electrolyte compositions. Herein, for comprehensive atomistic insights and the development of electrolyte scientific theory, molecular dynamics technology is employed to investigate the electrochemical properties of recently attractive poly(1,3-dioxolane)-based electrolytes and their interfaces with lithium metal. This work elaborates on the characteristics of Li+ solvation environments and the effects of polymer chain length or plasticizer content on the experiment-concerned properties of bulk electrolytes, including solvation sheath structures, ionic diffusions, conductivities, transport numbers, etc. Meanwhile, to clarify the influence of polymer or salt concentration on the electrolyte/lithium metal interface, three distinctive interface models were proposed and analyzed based on different electrolyte compositions in this work: liquid-based, polymer-based, and highly-concentrated systems. Compared with the unfavorable liquid interface layer in the liquid-based system, the latter two systems have more electrochemically stable interfacial construction due to the appearance of polymer on the lithium metal surface. Besides, the Li+ solvation structure, which is related to the lithium electrodeposition, exhibits orientation, e.g., small organic liquid molecules in the liquid-based system are more likely to appear on the side that is accessible to the lithium metal surface. These small molecules are essentially excluded from the Li+ solvation structures in the polymer-based electrolyte, which is another important factor for stabilizing the interface. Furthermore, compared with the bulk electrolytes, it is found that ionic conductions at the interfaces are not attenuated in all systems. This work presents a comprehensive, profound view from bulk to interfacial properties, thus providing a theoretical cornerstone for the composition design and performance optimization of polymer electrolytes for lithium metal batteries.

Microstructure and blowing agent concentration analysis in accelerated aged polyurethane & polyisocyanurate insulation

Some closed cell foam insulation products show an increase in thermal conductivity at low temperatures. This reduction in thermal performance has been attributed to the diffusion of air and blowing agent through the foam and to the condensation of the blowing agent. Aging processes and polymer degradation further increase the thermal conductivity of foams. The initial cell structure plays a role in dictating the thermal performance and changes with foam aging which is rarely investigated. To understand the loss of thermal performance in closed cell foams, a microstructure and chemical characterization of pristine and aged samples was performed in this study. The aging behaviour was analyzed by SEM imaging and by measuring the blowing agent concentration in the foam. Changes in the polymer physical attributes were identified. This study also used gas chromatography and quantified changes in pentane concentration in aged polyisocyanurate foams. Results show that aged foams undergo change in their polymer appearance and cellular elongation. Gas chromatography quantified a decrease in blowing agent in the range of 11-85% for polyisocyanurate foams after aging.

Preparation of Fully Bio-Based UV-Cured Non-Isocyanate Polyurethanes From Ricinoleic Acid

Fully bio-based non-isocyanate polyurethane (NIPU) was facilely prepared by self-condensation of primary amide of ricinoleic acid under oxidation conditions. The resulting linear urethane oligomer (Mn = 1300 Da) as a viscous liquid was further cured under UV light irradiation to afford a polymer film with hardness of lower than 2B. Infrared spectra as well as changes of polymer appearance proved crosslinking of the linear NIPU. Hardness of UV-cured film was promoted to 4H when a certain amount of cardanol was added to the linear urethane oligomer, accompanied by manifest improvement of resistance to chemical media such as aqueous HCl, EtOH, toluene and THF.

Chapter One - Isolation and Characterization of Chitin and Chitosan from Marine Origin

Nowadays, chitin and chitosan are produced from the shells of crabs and shrimps, and bone plate of squid in laboratory to industrial scale. Production of chitosan involved deproteinization, demineralization, and deacetylation. The characteristics of chitin and chitosan mainly depend on production processes and conditions. The characteristics of these biopolymers such as appearance of polymer, turbidity of polymer solution, degree of deacetylation, and molecular weight are of major importance on applications of these polymers. This chapter addresses the production processes and conditions to produce chitin, chitosan, and chito-oligosaccharide and methods for characterization of chitin, chitosan, and chito-oligosaccharide.

(+)-Catechin−Aldehyde Condensations: Competition between Acetaldehyde and Glyoxylic Acid

(+)-Catechin reaction with two aldehydes (acetaldehyde and glyoxylic acid) was studied in winelike model solution. The two aldehydes were reacted either individually or together with (+)-catechin and in molar excess. The reactions were followed by HLPC-UV and HPLC-ESI/MS to monitor (+)-catechin disappearance as well as dimer and polymer appearance. In all reactions a reaction order of close to 1 for (+)-catechin disappearance was observed. (+)-Catechin disappearance was slower in the presence of acetaldehyde (t(1/2) = 6.7 +/- 0.2 h) compared to glyoxylic acid (t(1/2) = 2.3 +/- 0.2 h). When the two aldehydes were reacted together, (+)-catechin disappearance was faster (t(1/2) = 2.2 +/- 0.5 h). When aldehydes were reacted separately, the dimer appearance was independent of the type of aldehyde used but the ethyl-bridged dimer disappearance was slower with acetaldehyde. When aldehydes were reacted together, the dimer appearance changed. Ethyl-bridged dimers appeared before carboxymethine-bridged dimers, and their disappearance occurred earlier. Copolymers containing both ethyl and carboxymethine bridges were also observed.

Visualization of Fluid-Loss Polymers in Drilling-Mud Filter Cakes

Summary The appearance of fluid-loss polymers in freeze-dried drilling-mud filter cakes was studied with scanning-electron-microscope (SEM) photography. Three fluid-loss polymers were studied: starch, polyanionic cellulose (PAC), and a high-temperature- (HT)-stable, sulfonated polymer. The effects of electrolyte contamination (NaCl, CaCl2, and MgCl2) and temperature (200 to 350°F) on the appearance of the fluid-loss polymers were also studied. A correlation between API filtrate and polymer appearance was sought.

Kinetics of Malvidin‐3‐Glucoside Condensation in Wine Model Systems

ABSTRACTWine model systems containing equimolar quantities of malvidin‐3‐glucoside and d‐catechin, with and without acetaldehyde, were stored anaerobically at 22, 32, 42, and 52°C. Malvidin‐3‐glucoside and d‐catechin disappearance and polymer appearance were monitored by HPLC and colorimetric methods. Reaction rates and activation energies were calculated. The malvidin‐3‐glucoside and d‐catechin condensation reactions showed pseudo first order kinetics both with and without the presence of acetaldehyde. However, activation energies were not significantly different.

Kinetics of sickle haemoglobin polymerization in single red cells.

Kinetic studies on solutions of purified haemoglobin S indicate that the rate of intracellular polymerization is an important variable in the pathophysiology of sickle cell disease. Until now, however, no experimental technique has been available to measure directly the kinetics of intracellular polymerization. Indirect methods, which use visual determination of cellular shape changes or changes in filterability of red cell suspensions, have given apparently conflicting results. Here we report our initial results on the application of a laser-photolysis, light scattering technique to measure directly the kinetics of haemoglobin S polymerization in single red cells. In our experiment, deoxyhaemoglobin S is rapidly formed by photolysing the carbon monoxide complex with an argon ion laser focused inside the cell, and the change in scattered light is used to detect the appearance of polymer. We find a very wide distribution of delay times, ranging from 1 ms to greater than 100 s, indicating that the polymerization inside red cells proceeds by the same nucleation and growth mechanism as in solutions of purified haemoglobin S.

Characteristic protein fractions of cerebrospinal fluid disc electrophoretic analysis

The present work was undertaken to determine characteristic proteins of normal cerebrospinal fluid (CSF) by disc electrophoresis in polyacrylamide gel, and to evaluate their usefulness as indicators of blood-brain-CSF barrier disturbance. The technique has been applied to 1280 samples of unconcentrated CSF obtained from 27 reference subjects and 847 neurological patients, with a simultaneous analysis of 361 sera. The pre-albumin content (mean ± S.D. as a percentage of total protein, 11.0 ± 2.3%) was higher than formerly reported. One reason for this is that preliminary concentration was not necessary, and the second is related to the principle of protein resolution. The no. 5 protein band of the post-albumin group (3.9 ± 1.1% was characteristic, though it has not yet been identified. The no. 3 protein band of the post-transferrin group (5.2 ± 1.7%)was highly specific to CSF; it was found to be closely related to transferrin, and may correspond to τ fraction obtained by other methods. Barrier dysfunction was easily recognizable by the appearance of polymers of haptoglobin 2-1 or 2-2, because only haptoglobin 1-1 was detected in normal CSF. The percentage of the main region of the G-zone (13.7 ± 2.6%) was postulated as normal content of CSF immunoglobulins.

Equilibrium polymerization of selenium

AbstractA theory of the ring‐chain equilibrium in liquid selenium is presented which is mathe‐matically identical to our theory for polymer equilibrium in liquid sulfur. The numerical treatment is based on: (a) the entropy and enthalpy of the propagation reaction (Sen* + Se8 ⇌ Sen+8*, the asterisk denoting a diradical) which were calculated from values of the Se8 concentrations in the liquid as given in the literature, and (b) the entropy and enthalpy of the initiation reaction (Se8 ⇌ Se8*) which were estimated by comparison to the sulfur values. The “transition” temperature for the appearance of polymer in the liquid state is calculated as 83°C. (134° below the melting point of selenium), and the chain length at the melting point is estimated as ca. 1300 Se8 units.