Morphology, Rheological and Mechanical Properties of Isotropic and Anisotropic PP/rPET/GnP Nanocomposite Samples

The effect of graphene nanoplatelets (GnPs) on the morphology, rheological, and mechanical properties of isotropic and anisotropic polypropylene (PP)/recycled polyethylene terephthalate (rPET)-based nanocomposite are reported. All the samples were prepared by melt mixing. PP/rPET and PP/rPET/GnP isotropic sheets were prepared by compression molding, whereas the anisotropic fibers were spun using a drawing module of a capillary viscometer. The results obtained showed that the viscosity of the blend is reduced by the presence of GnP due to the lubricating effect of the graphene platelets. However, the Cox–Merz rule is not respected. Compared to the PP/rPET blend, the GnP led to a slight increase in the elastic modulus. However, it causes a slight decrease in elongation at break. Morphological analysis revealed a poor adhesion between the PP and PET phases. Moreover, GnPs distribute around the droplets of the PET phase with a honey-like appearance. Finally, the effect of the orientation on both systems gives rise not only to fibers with higher modulus values, but also with high deformability and a fibrillar morphology of the dispersed PET phase. A fragile-ductile transition driven by the orientation was observed in both systems.

Enhancing Rheological Properties and Reduction of Total Acid Number of a Heavy Crude Oil Using Ethanol and Trona

One of Sudanese fields has a heavy crude oil which has a high Total Acid Number (TAN) and high viscosity, can cause a lot of problems in production operation, transport, and storage facilities. The effect of ethanol dilution on the rheological properties of crude (especially the kinematic viscosity) was studied and presented. Moreover, the consequence of blending Trona (NaHCO3.Na2CO3) with a specified amount of Ethanol in the crude can reduce (TAN) to acceptable limits for solving corrosion and flowability problems. The approach is based on the experiments and laboratory works on the crude's samples after blending with a certain amount of Trona and Ethanol. It depends on the results of apparatuses, that are used to measure the samples, for instance, Calibrated glass capillary viscometer and ASTM D664 titration volume Total Acid Number tester which are employed to get the values of kinematic viscosity and TAN, respectively. The tests are established with crude have kinematic viscosity (187 cst) at temperature 75°C and TAN almost (8.51). While increasing the dosage of Trona at the ambient temperature (38°C) with the certain mass percentage of Ethanol (5%), TAN is decreased from (8.51 to 4.00 mgKOH/g). Also, the kinematic viscosity is declined from (187 cst to 96.75 cst) after increasing the volume of Ethanol at 75°C. These outcomes indicated that Ethanol could reduce Sudanese heavy crude's viscosity, and the Trona could decrease the TAN. This reduction occurred due to Ethanol dilution. The Ethanol molecules disturb the molecular structure of the crude, which forms polar bond within the hydrocarbon chain that leads to lower the friction between molecules of hydrocarbon in the crude. Also, Trona shrinks TAN because the Hydroxide ions (OH+) that founded in Trona neutralize the Hydrogen ions (H−) in Naphthenic acid in Sudanese heavy crude. This study can be summarized in the ability to solve the difficulty of transporting and processing the heavy crude oil in refineries; maintains the quality of the crude while utilizing it with friendly environmental materials and low cost.

Investigation of the dependences of the rheology of calcium alginate solutions on concentration, temperature and shear rate

The main problem: The rheological properties of calcium salts are of theoretical and practical interest for a modern researcher. The theoretical interest is primarily related to the search for general patterns and manifestations of the rheological properties of solutions of calcium salts. The practical component is based on the search for patterns and dependencies of the properties of solutions on the structure and composition of the object of study. Such chemicals as calcium salts are of particular practical interest, they are widely used in various fields, such as the food, chemical and pharmacological industries. Hydrophilic high-molecular solutions of alginates, namely calcium alginate, are actively used in the preparation of soft dosage forms, the manufacture of jelly masses in confectionery, act as thickeners in the food industry. They are characterized by a fairly high percentage of viscosity at low concentrations, bioavailability, prolonging effect, absence of irritating properties, biocompatibility with many polymers, which is especially important in the pharmaceutical industry and medicine. The use of calcium salts for these purposes is currently very promising, since these organic salts have a number of unique properties associated with gelation. Purpose: This paper contains the results of studying the features of the rheology of calcium alginate solutions. A concentration range of 0.1-0.7 % was chosen for the studies, which is sufficient to avoid gelation at room temperature. The dependence of viscosity on concentration, temperature (in the range of 25-45 °C) and shear rate were studied. Methods: Analysis of theoretical sources, observation, comparison of results. The rheological characteristics of the obtained substances were studied using a capillary viscometer. The measurements were carried out in the temperature range of 25-45°C. Results and their significance: it was found that there is a significant dependence of viscosity on concentration and temperature. For concentrations of 0.3 – 0.7 %, a similar type of dependence is observed, in contrast to solutions with a concentration of 0.1 % . Explanations of these dependencies were proposed.

Synthesis and Characterization of Caprolactam- based Ionic Liquids as Green Solvents

Aims: To synthesize and characterize six caprolactam-based ionic liquids (CPILs) by combination of caprolactam with different organic and inorganic Brønsted acids that can be utilized for lipid extraction from microalgae. Study design: Experimental design include quantitative and qualitative. Place and duration of study: The study was done at Department of Chemistry & Biochemistry, School of Sciences and Aerospace Studies, Moi University (Kenya) between November 2020 and May 2021. Methodology: Six CPILs were prepared through a simple neutralization reaction between Caprolactam and Brønsted acids such as Hydrochloric acid (HCl), Methane sulphonic acid (CH3SO3H), Trifluoromethanesulphonic acid (CF3SO3H), Acetic acid (CH3CO2H), Trifluoroacetic acid (CF3CO2H), and Sulfuric acid (H2SO4). The first three acids were used in the synthesis of CPILs for the first time. The chemical structures of the synthesized CPILs were characterized by Fourier transform infrared and Raman spectroscopy. The densities and viscosities were measured at 20 oC using the weight (pycnometer) and capillary viscometer (Oswald) methods, respectively. Results: All the CPILs were insoluble in hexane and had high miscibility with water and methanol. Fourier transform infrared and Raman spectra of the CPILs were compared with that of free Caprolactam. The characteristic absorption bands of the synthesized compounds showed a big shift in position and/or intensity (compared to caprolactam), indicating the formation of the CPILs. The results showed that both the density and viscosity increased with the molecular weight of the anion - except in Caprolactamium hydrogen sulphate (CPSA)- which could be due to the strong interactions between the cation and anion resulting from the dimerization between hydrogen sulphate anions. Conclusion: The hydrophilic nature of the CPILs indicated by high miscibility with polar solvents (water and methanol) indicates that they are suitable for the dissolution of cellulose of microalgae cell wall and thus could result in high lipid extraction efficiency. Further studies should therefore utilize the synthesized CPILs in lipid extraction from microalgae.

Application of FTIR-ATR Spectrometry in Conjunction with Multivariate Regression Methods for Viscosity Prediction of Worn-Out Motor Oils

Viscosity is considered to be a key factor in the quality of lubrication by oil and engine manufacturers and is therefore one of the most monitored parameters of lubricants. FTIR (Fourier-transform infrared) spectrometry in combination with Partial Least Squares (PLS) and Principal Component Regression (PCR) was therefore proposed and tested as an alternative to the standardized method for determining the kinematic viscosity at 100 °C with an Ubbelohde capillary viscometer (CSN EN ISO 3104) of worn-out motor oil grade SAE 15W-40. The FTIR-PLS model in the spectral region of 1750–650 cm−1 with modification of the spectra by the second derivative proved to be the most suitable. A significant dependence of R = 0.95 was achieved between the viscosity values of 190 samples of worn-out motor oils, which were determined by a standardized laboratory method, and the values predicted by the FTIR-PLS model. The Root Mean Square Error of Calibration (RMSEC) parameter reached 0.148 mm2s−1 and the Root Mean Square Error of Prediction (RMSEP) parameter reached 0.190 mm2s−1. The proposed method for determining the kinematic viscosity at 100 °C by the FTIR-PLS model is faster compared to the determination according to the CSN EN ISO 3104 standard, requires a smaller amount of oil sample for analysis and produces less waste chemicals.

Changes of Hematological and Hemorheological Parameters in Rabbits with Hypercholesterolemia

Hypercholesterolemia plays an important role in the development of atherosclerosis, leading to endothelial dysfunction, ischemic events, and increased mortality. Numerous studies suggest the pivotal role of rheological factors in the pathology of atherosclerosis. To get a more detailed hematological and hemorheological profile in hypercholesterolemia, we carried out an experiment on rabbits. Animals were divided into two groups: the control group (Control) was kept on normal rabbit chow, the high-cholesterol diet group (HC) was fed with special increased cholesterol-containing food. Hematological parameters (Sysmex K-4500 automate), whole blood and plasma viscosity (Hevimet-40 capillary viscometer), red blood cell (RBC) aggregation (Myrenne MA-1 aggregometer), deformability and mechanical stability (LoRRca MaxSis Osmoscan ektacytometer) were tested. The white blood cell and platelet count, mean corpuscular volume, and mean corpuscular hemoglobin were significantly higher in the HC group, while the RBC count, hemoglobin, and hematocrit values were lower than the Control data. Viscosity values corrected to 40% hematocrit were higher in the HC group. The RBC aggregation significantly increased in the HC vs. the Control. The HC group showed significantly worse results both in RBCs’ deformability and membrane stability. In conclusion, the atherogenic diet worsens the hematological and macro- and micro-rheological parameters, affecting blood flow properties and microcirculation.

Measuring Kinematic Viscosity of Engine Oils: A Comparison of Data Obtained from Four Different Devices

The aim of this paper is to compare the results of kinematic viscosity of lubricating oils measurements at 40 °C, obtained with three different rapid evaluation devices, and the standardized method using an Ubbelohde Capillary viscometer. The following instruments were selected to measure: a mid-FTIR spectrophotometer, a microchannel viscometer, and a Stabinger viscometer. The study material comprised 42 fresh engine oils, all of which are commercially available. The main data analysis tools used in the study were multiple regression, Mahala Nobis distance, post-hoc analysis, and the Wilcoxon signed-rank test with the Bonferroni correction. Consistent outcomes were obtained for the Stabinger viscometer only, whereas the microchannel viscometer and the mid-FTIR spectrophotometer were not as precise as the reference method. It was also found that the results obtained with the use of the mid-FTIR spectrophotometer were burdened with a very large measurement error. Therefore, a very careful approach is suggested when choosing these instruments. The study fills an important gap in empirical research in the context of the reliability of measurement results obtained using various research techniques.

Preparation and Performance of Supercritical Carbon Dioxide Thickener

The low sand-carrying problem caused by the low viscosity of supercritical carbon dioxide (SC–CO2) limits the development of supercritical CO2 fracturing technology. In this study, a molecular simulation method was used to design a fluorine-free solvent-free SC–CO2 thickener 1,3,5,7-tetramethylcyclotetrasiloxane (HBD). Simulations and experiments mutually confirm that HBD-1 and HBD-2 have excellent solubility in SC–CO2. The apparent viscosity of SC–CO2 after thickening was evaluated with a self-designed and assembled capillary viscometer. The results show that when the concentration of HBD-2 is 5 wt.% (305.15 K, 10 MPa), the viscosity of SC–CO2 increases to 4.48 mPa·s. Combined with the capillary viscometer and core displacement device, the low damage of SC–CO2 fracturing fluid to the formation was studied. This work solves the pollution problems of fluoropolymers and co-solvents to organisms and the environment and provides new ideas for the molecular design and research of SC–CO2 thickeners.