Decrease In Viscosity Research Articles

Low-calorie functional dairy dessert enriched by prebiotic fibers and high antioxidant herbal extracts: A study of optimization and rheological properties.

The formulations of functional low-calorie dairy dessert, enriched with inulin/polydextrose (as a starch substitute), and ginger/cinnamon extract (as a flavor component and natural antioxidants), were developed and optimized by the D-optimal mixed design method. In the first stage, using the hedonic sensory evaluation and syneresis data, the optimal concentrations of inulin and polydextrose were obtained as 2.49% inulin and 1.51% polydextrose, respectively. The steady shear rheological test showed that the replacement of starch with inulin and polydextrose caused a decrease in apparent viscosity in all dessert samples. This decrease was higher in the samples containing polydextrose than those containing inulin. The replacement of starch with inulin and polydextrose also reduced the hysteresis loop area and thixotropic behavior. In the second stage, 0-0.4% of ginger and cinnamon extracts were added to the optimum sample and then the antioxidant and color properties of dessert samples were evaluated. The lightness (L*) Hunter parameter decreased by adding extracts and the samples containing cinnamon extract showed a higher a* parameter than the control and ginger-incorporated samples. The result of the 2,2-diphenyl 1-picrylhydrazyl (DPPH) antioxidant assay showed that the antioxidant capacity of ginger extract was significantly higher than that of cinnamon extract. The half-maximal inhibitory concentration (IC50) value of dessert samples decreased by adding 0.4% cinnamon and ginger extracts from 88.30 mg/mL to 77.04 and 31.94 mg/mL, respectively.

Rotor–stator hydrodynamic cavitation reactor for intensification of castor oil biodiesel production

AbstractNowadays, the intensification of the production of biodiesel from non-edible oil crops is mandatory to overcome petrol-fuel depletion and environmental pollution. For the first time, enhanced biodiesel production from castor oil via rotor–stator hydrodynamic cavitation has been studied in this work. Response surface methodology based on one-factor-at-a-time design of experiments was employed for modelling and optimizing the biodiesel yield and the decrease in feedstock viscosity, density, and total acid number (TAN). The predicted optimum parameters of 8.15:1 methanol:oil (M:O), 1499 rpm, 29.38 min, 48.43 °C, and a KOH catalyst concentration of 0.74 wt.% resulted in a 96% biodiesel yield with a concomitant decrease in viscosity, density, and TAN of approximately 95%, 5.12%, and 90.02%, respectively. According to the results of the breakthrough kinetic calculations, the reaction is pseudo-second order, with the activation energy, frequency factor, and reaction rate constant being 0.23 M−1 min−1, 18.77 kJ/mol, and 6.32 M−1 min−1, respectively. The fuel properties of the produced biodiesel and bio-petro-diesel blends were good, comparable to international standards and the marketed Egyptian petro-diesel.

Sustainable polymer reclamation: recycling poly(ethylene terephthalate) glycol (PETG) for 3D printing applications

Due to their versatile properties and wide-ranging applications across various industries, including manufacturing, polymers are indispensable for today’s society. However, polymer-based products significantly impact the environment since many are single-used plastics and require a long time to degrade naturally. A method to attenuate end-of-life polymers’ ill effects is recycling them to bring them again into the production cycle, from grave to cradle. This investigation involves recycling PETG sheets used in face shield production during the COVID-19 outbreak to fabricate 3D printing filaments for FFF. We assessed poly(ethylene terephthalate) glycol (PETG) processability to up to five recycling cycles and obtained filaments with properties adequate for 3D printing. Rheological, thermal, morphological, and mechanical characterization were analyzed to verify the effect of the number of processing cycles on the properties of the polymer. The recycling cycles originated a decrease in viscosity and elasticity, and the gain in molecular mobility resulted, relatively, in solids with a higher degree of crystallinity and prints with more elliptical depositions. The mechanical properties of printed parts fabricated of recycled material were comparable to those from commercial filament, especially after three extrusion cycles. Both extrusion and additive manufacturing processes successfully recycle material into filaments and printed parts, indicating that the proposed methodology is a promising alternative to bring value back to polymers from solid waste.

Structural evolution of maize starches with different amylose content during pasting and gelation as evidenced by Rapid Visco Analyser

This study examined multi-scale structural alterations of maize starches varying in amylose content during pasting and gelation, using Rapid Visco Analyser (RVA). At 50 °C, starch granules maintained their morphology with low viscosity. As the temperature increased to 95 °C, helical and crystal structures were destroyed, leading to granule swelling, distortion and porosity, as identified by Wide Angle X-ray Scattering and Fourier Transforms Infrared measurements at 90% moisture. This resulted in increased viscosity and the formation of a loose gel network structure. Subsequently, maintaining the temperature at 95 °C caused a decrease in viscosity as most granules disappeared, forming a reorganized flaky gel structure with larger pores. As the temperature decreased, gel porosity reduced. In high amylose content starch, the viscosity remained low and granules were partially gelatinized since the heating temperature was below the gelatinization temperature. This study is the first to detail starch multilevel structural dynamics during RVA gelatinization.

Removal of proteins and lipids affects structure, in vitro digestion and physicochemical properties of rice flour modified by heat-moisture treatment.

The objective of this experiment was to investigate the role of endogenous proteins and lipids in the structural and physicochemical properties of starch in heat-moisture treatment (HMT) rice flour and to reveal their effect on starch digestibility under heat. The findings indicate that, in the absence of endogenous proteins and lipids acting as a physical barrier, especially proteins, the interaction between rice flour and endogenous proteins and lipids diminished. This reduction led to fewer starch-protein inclusion complexes and starch-lipid complexes, altering the granule aggregation structure of rice flour. It resulted in a decrease in particle size, an increase in agglomeration between starch granules, and more surface cracking on rice granules. Under HMT conditions with a moisture content of 30%, slight gelatinization of the starch granules occurred, contributing to an increased starch hydrolysis rate. In addition, the elevated thermal energy effect of HMT enhanced interactions between starch molecular chains. These resulted in a decrease in crystallinity, short-range ordering, and the content of double-helix structure within starch granules. These structural transformations led to higher pasting temperatures, improved hot and cold paste stability, and a decrease in peak viscosity, breakdown, setback, and enthalpy of pasting of the starch granules. The combined analysis of microstructure, physicochemical properties, and in vitro digestion characteristics has enabled us to further enhance our understanding of the interaction mechanisms between endogenous proteins, lipids, and starches during HMT. © 2024 Society of Chemical Industry.

Marangoni Droplets of Dextran in PEG Solution and Its Motile Change Due to Coil-Globule Transition of Coexisting DNA.

Motile droplets using Marangoni convection are attracting attention for their potential as cell-mimicking small robots. However, the motion of droplets relative to the internal and external environments that generate Marangoni convection has not been quantitatively described. In this study, we used an aqueous two-phase system [poly(ethylene glycol) (PEG) and dextran] in an elongated chamber to generate motile dextran droplets in a constant PEG concentration gradient. We demonstrated that dextran droplets move by Marangoni convection, resulting from the PEG concentration gradient and the active transport of PEG and dextran into and out of the motile dextran droplet. Furthermore, by spontaneously incorporating long DNA into the dextran droplets, we achieved cell-like motility changes controlled by coexisting environment-sensing molecules. The DNA changes its position within the droplet and motile speed in response to external conditions. In the presence of Mg2+, the coil-globule transition of DNA inside the droplet accelerates the motile speed due to the decrease in the droplet's dynamic viscosity. Globule DNA condenses at the rear part of the droplet along the convection, while coil DNA moves away from the droplet's central axis, separating the dipole convections. These results provide a blueprint for designing autonomous small robots using phase-separated droplets, which change the mobility and molecular distribution within the droplet in reaction with the environment. It will also open unexplored areas of self-assembly mechanisms through phase separation under convections, such as intracellular phase separation.

The Role of Lower Crustal Rheology on Surface Deformation During Oblique Extension: Insights From Sandbox Modeling

AbstractExtensive researches have been conducted on the relationship between surface deformation and the properties of upper crust. However, the link between surface deformation and lower crustal rheology, especially in a three‐dimensional context, remains unclear. In this study, we utilize sandbox modeling to investigate the impact of lower crustal rheology on surface deformation during oblique extension. Under the same conditions, six models with different lower crustal viscosities, both with and without syn‐kinematic deposits, are conducted. The results indicate that a decrease in lower crustal viscosity may contribute to an increase in: (a) graben width, (b) graben length, (c) graben spacing, (d) the number of isolated rifts and (e) topographic relief of oblique extensional systems, while also leading to a reduction in the total number of grabens. Notably, there exists a negative linear correlation between graben spacing and lower crustal viscosity. In map view, the angle between fault strike and the direction of pre‐existing discontinuities increases as the viscosity of the lower crust decreases. Furthermore, the frequency of large rakes (>50°) decreases with decreasing lower crustal viscosity. These findings align with natural examples such as the East African Rift System, Weihe Graben and the South Tibetan Rift in terms of geomorphology, tectonics, and crustal rheology. Through a comprehensive comparison of the graben width, spacing, and the angle between fault strike and the direction of pre‐existing discontinuities, our study provides valuable insights into the rheology of the lower crust in natural settings.

The multi-modal sensory effect on sour taste perception during oral processing of starch-thickened fluids

Sour taste is one of the fundamental taste attributes and considered as a saliva secretion stimulant facilitating consumers with xerostomia and swallowing difficulties. The dynamic sour taste perception during oral processing of starch-thickened fluid was therefore investigated in this study. Recruited healthy subjects were divided into those with high (H_AMS) and low (L_AMS) salivary α-amylase activity groups and their temporal dominant sensory evaluation were analyzed while oral processing starch-thickened fluid samples with different concentration of citric acid. By simultaneously evaluating the physical and chemical properties of subjects' expectorated fluid/saliva mixtures, the complex and multi-modal interplay between fluid viscosity (tactile perception), citric acid concentration (taste perception), salivary α-amylase activity (binary taste interaction) was successfully demonstrated. The sour taste perception was found to be greatly affected by the continuous starch-thickened fluid hydrolysis by salivary α-amylase, resulting in a gradual production of sweet-tasting oligosaccharides and simultaneous decrease in fluid viscosity, and group variations (H_AMS vs. L_AMS) were pronouncedly observed in the hydrolyzed oligosaccharide concentrations (glucose, maltose, and maltotriose) which suitably corresponded to the selected dominant sensory attributes including perceived taste differences and taste dominant duration. These findings suggest that salivary biochemical properties and the thickened fluid type greatly influence consumers’ sensory perception. This could provide valuable insights for designing and optimizing thickened foods and beverages that are palatable in sensory properties and meet the needs of special consumers.

Ferulic acid and human platelet lysate incorporated alginate dialdehyde‐gelatin 3D (bio)printable hydrogels with biological activity

AbstractThis study investigates the creation of multifunctional scaffolds based on alginate dialdehyde (ADA) and gelatin (GEL) incorporating ferulic acid (FA), a phytotherapeutic agent with diverse pharmacological properties, and human platelet lysate (HPL). The multimaterial hydrogels were characterized in terms of degradation/swelling behavior showing that HPL decelerates the degradation process of ADA‐GEL hydrogels in absence of FA. A FA release study confirmed that the presence of HPL does not affect the FA release ability of ADA‐GEL hydrogel. A trinitrobenzenesulfonic acid (TNBS) assay confirmed no influence of HPL on the Schiff's base formation. The addition of HPL was shown to lead to a decrease in stiffness, mechanical stability, and viscosity of ADA‐GEL‐HPL inks. This effect was also observed for ADA‐GEL‐HPL inks when investigating their three‐dimensional (3D) printing ability. Cytocompatibility tests and a 3D bioprinting study confirmed the beneficial impact of the addition of HPL on MC3T3‐E1 cells. Moreover, an antibacterial effect provided by the addition of FA was confirmed while the incorporation of HPL led to higher VEGF‐A expression by MC3T3‐E1 cells. Overall, the addition of HPL and FA to ADA‐GEL hydrogel results in a promising ink, which has potential for future biofabrication applications.

Thermophysical properties, crystallization behavior and structure of CaO–SiO2–MgO–Al2O3–TiO2–FeO slag with varying TiO2 contents

This study investigated the effect of TiO2 content on the viscosity, free running temperature, electrical conductivity, crystallization behavior, and structure of high-titanium CaO–SiO2-10 wt% MgO-13 wt%Al2O3–TiO2-4 wt.% FeO slag by experiments and molecular dynamics simulations. The results revealed that increasing TiO2 weakened the overall bonding energy and simplified the slag structure, leading to a decrease in viscosity and an increase in electrical conductivity. Thermodynamic calculations revealed a continuous enrichment of the slag towards the pseudobrookite region with increasing TiO2 content. The precipitation of pseudobrookite phase during cooling resulted in short-slag characteristics and a rising free running temperature. Additionally, the peak intensity of pseudobrookite phase gradually enhanced and its morphology changed from elongated strips to plates with higher TiO2 concentration. Structural analysis demonstrated that the poorly stabilized [TiO6] octahedron was the major form of Ti atoms in the slag, and its proportion progressively increased with increasing TiO2 content.

The use of xanthan gum in a milk-containing ice cream with the whey protein microparticulate

Hydrocolloids of stabilization systems are necessary components in ice cream production. They influence viscosity, stabilization of structural elements and melting rate. Their role is especially important in production of ice cream with the low content of fat and nonfat milk solids. Today, specialized stabilization systems for production of such ice cream are absent. Moreover, when choosing stabilization systems, there are problems of economic character that are linked with an increase in prices on the effective polysaccharide — locust bean gum. The aim of the research was substantiation of the composition of the effective formulation of hydrocolloids using their available variety, xanthan gum, to use in production of milk-containing ice cream (with the reduced content of fat and dry nonfat milk substances). To achieve the best quality indicators, a whey protein microparticulate was introduced into milk-containing ice cream. Based on the synergetic properties of hydrocolloids in terms of dynamic viscosity, the composition of four formulations was determined with the content of xanthan gum of 8.6% (in samples 1 and 2), 16% (in sample 3) and 3% (in sample 4). Ice cream with the complex stabilization system of the trademark Cremodan 334 was produced as a control sample. The following indicators were determined in all samples: dynamic viscosity, viscoelastic characteristics (hardness, adhesion strength, gumminess), melting rate, condition and dispersity of the air phase and ice crystals. All developed formulations were superior to the control sample in terms of viscosity by 1.2–2 times. It has been found that replacement of the kappa-carrageenan fraction with iota-carrageenan in combination with guar gum and xanthan gum in an amount of 50% leads to a decrease in viscosity by 1.3 times. A reduction of visco-elastic characteristics was noted in the samples of hydrocolloid formulations under study. When using iota-carrageenan (samples 2 and 4), a notable reduction of thermal stability of ice cream was revealed in sample 4. Furthermore, a decrease in dispersity of the air phase was observed; the content of air bubbles with a size of 50 µm reduced by almost 30%. Based on the results of the investigations, it has been established that the formulation of hydrocolloids of ice cream sample 1, which consists of mono- and di-glycerides of fatty acids, guar gum, xanthan gum and kappa-carrageenan, allows obtaining a product with technologically necessary quality indicators and the most cream-like consistency.

3D Printer Nozzle Structure Form Optimal Structural Analysis

The most representative technology of 3D printing is fused deposition modeling (FDM). To improve the printing accuracy of FDM technology, this paper first takes the outlet diameter, angle of convergence, and rectifier section length of the nozzle as the influencing factors. It takes the melt outlet speed stability, viscosity, and outlet pressure as the indexes to design the orthogonal test. Then, COMSOL Multiphysics fluid–solid coupling simulation was used to simulate and analyze the structural characteristics of the 3D printer nozzle, and the range analysis method was used to analyze the data. Finally, the two-phase flow combination was used to simulate the morphological characteristics of the melt flowing out of the nozzle. The results show that the simulation results of the two materials are similar. As the nozzle diameter decreases, the melt pressure decreases, the velocity increases, and the viscosity decreases. For PLA wire rods, the optimal structure of the nozzle is that the outlet diameter is 0.2 mm, the rectifier section length is 1.5 mm, and the angle of convergence is 60°. For ABS wire, the optimum structure of the nozzle is that the outlet diameter is 0.2 mm, the rectifier section length is 1.5 mm, and the angle of convergence is 30°. The nozzle outlet diameter is inversely proportional to the printing accuracy for ABS and PLA materials. The research results provide a theoretical reference for optimizing the nozzle structure for 3D printing.

Effect of magneto-thermal conditions on blood viscosity: An experimental study

The effects of the combined magneto-thermal conditions on blood viscosity and the underlying mechanisms of the key factors were elucidated. An integrated magneto-thermal experimental apparatus was devised to measure the viscosity of blood samples sourced from healthy blood donors subject to various non-thermal alternating magnetic fields (AMF), temperature, and magneto-thermal conditions. Mechanisms governing the influence of different factors on blood viscosity were further probed by assessing the viscoelastic modulus of red blood cells (RBCs) and observing RBC morphology. Results show that the hierarchy of significance of three main factors in magnetic hyperthermia on blood viscosity is as follows: temperature > AMF intensity > AMF frequency. Both heightened AMF field strength and elevated temperature led to a nonlinear decrease in blood viscosity, particularly in blood samples with higher hematocrit levels. This is associated with enhanced rheological characteristics of RBCs at increased temperatures and alterations in the repulsive forces between RBCs owing to changes in the cell surface charge induced by AMF. These changes ultimately reduce the flow resistance. However, when the temperature exceeded 46 °C, the deterioration of spectrin on the RBC membrane, coupled with the formation of spicules on the cell membrane surface and subsequent RBC rupture, contributed to increased blood viscosity at higher temperatures.

Utilizing combusted PET plastic waste and biogenic oils as efficient pour point depressants for crude oil

The deposition of paraffin on pipelines during crude oil transit and low-temperature restart processes poses a significant challenge for the oil industry. Addressing this issue necessitates the exploration of innovative materials and methods. Pour point depressants (PPDs) emerge as crucial processing aids to modify paraffin crystallization and enhance crude oil flow. This study focuses on the combustion of polyethylene terephthalate (PET) waste, a prevalent plastic, in two distinct oils (castor and jatropha). The resulting black waxy substances (PET/Castor and PET/Jatropha) were introduced in varying weights (1000, 2000, and 3000 ppm) to crude oil. The PET/castor oil combination demonstrated a remarkable reduction in pour point from 18 to −21 °C at 3000 ppm concentration, significantly more effective than PET/jatropha blends. Substantial decreases in viscosity (up to 75%) and shear stress (up to 72%) were also observed for both blends, most prominently at lower temperatures near the pour point. The synergistic effect of PET and oils as nucleating agents that alter crystallization patterns and restrict crystal growth contributes to this enhanced low-temperature flow. This highlights the potential of PET plastic waste as an economical, abundant, and eco-friendly additive to develop high-performance PPDs for crude oil.

Ionic strength effect on the structure and dynamics of colloidal dispersions with weak attractive interactions

We present a macro- and microrheological study of the effect of ionic strength on the phase behavior, structure and flow properties of colloidal dispersions stabilized by short-range repulsive interactions inferred via co-polymerization of weak acid groups. We investigated the impact of ionic strength, by varying the concentration of natrium chloride (NaCl), on dispersions with only repulsive interactions, but also when additional attractive depletion forces are present due to added non-absorbent polymer, namely polyethyleneoxide (PEO). For dispersions with only repulsive electrosteric interactions, at low particle volume fractions (ϕ < 0.4), increasing ionic strength hardly affects the relative viscosity whereas at higher particle volume fractions, a decrease in viscosity is observed due to a reduced range of electrosteric repulsion between particles, corresponding to a reduction of the effective particle volume fraction ϕeff. For dispersions including attractive interactions, at volume fractions ϕ = 0.45 below the hard sphere freezing point (ϕc=0.5), independently of the ionic strength, the bulk viscosity increases monotonically with increasing PEO concentration due to the transition from a fluid to a fluid/crystalline and finally to a gel state. However, the increase in ionic strength shifts the concentrations of both phase transitions to lower polymer concentrations, indicating that in presence of salt a weaker attraction is required to induce these transitions. At ϕ=0.52, just above ϕc, for dispersions without added salt, broadening of the fluid-crystalline coexistence regime, due to added PEO, results in a viscosity minimum corresponding to different size and packing density of the crystalline regions as observed earlier in Weis et al. [1]. When salt is added, the initial state for dispersions without PEO is a fluid state due to the reduction of ϕeff and the addition of a small amount of PEO leads to an increase in bulk viscosity due to the formation of large crystals for dispersions containing 10 mM NaCl and a network of small, dense crystals of size ≈10 µm when 100 mM NaCl is added. At ϕ=0.54, a result similar to ϕ=0.52 is obtained for dispersions without added salt, whereas in presence of salt, we find that the fluid/crystalline coexistence regime narrows down as the range of electrosteric repulsion decreases and the addition of PEO results in gel formation and gels become more uniform with increasing attraction strength. These investigations demonstrate how superimposed short range electrosteric repulsion and weak depletion attraction affect microstructure and flow behavior of colloidal dispersions.

Investigation of the ageing behaviour of multiple reused polypropylene binding twines

AbstractClimate change is one of the significant challenges of the 21st century. To achieve climate goals a change in plastic waste management needs to be implemented. This research examines the potential of thermo‐mechanical recycling of plastic waste, focusing on agricultural binding twines made from polypropylene. Old binding twines from agriculture were collected and recycled with a twin screw extruder. The ageing behaviour of the recyclate in terms of multiple recycling is examined in detail with tensile tests and melt volume rate measurements. The findings indicate a general degradation in mechanical properties and a decrease in viscosity due to molecular chain scission. Despite these degradations, the material remains processable, indicating the potential for continued recycling loops.

Flaking of millets and its impact on bioactivity, pasting, digestibility, structural and thermal properties

Five different millets (foxtail, little, barnyard, kodo and browntop) with and without sprouting were subjected to flaking. Phytic acid and phenolic content tends to decrease significantly, whereas antioxidant activity increased up to 77.32% on flaking of millets. A significant decrease in peak and final viscosity was observed in millet flakes. A-type diffraction pattern was predominant for unsprouted millets whereas the flaked millets showed V-type crystallinity. The protein digestibility significantly increased up to 37.77% in flakes made from sprouted millets. The mineral bioavailability upon flaking of millets increased, especially Ca (88.22% for little), Fe (43.04% for barnyard) and Zn (61.77% for kodo), which is attributed to the reduction in phytic acid. Flaking, however, led to an increase in rapidly and slowly digestible starch with a corresponding decrease in resistant starch. Among the unsprouted and sprouted millet flakes, foxtail received the highest sensory scores for overall acceptability.

Experimental Study of the Rising Behavior of a Single Bubble in Shearshinning Fluids

Background: Non-Newtonian gas-liquid two-phase flows are often seen in industrial processes such as petroleum, chemical, and food engineering. The efficiency of mass and heat transfer between phases is significantly impacted by bubble rise motion in liquids. Therefore, it is crucial to deeply study the hydrodynamic characteristics of a bubble rising in non-Newtonian fluids to improve the transfer efficiency between phases and to enhance the operational efficiency of bubbling equipment. Methods: To understand the rising characteristics of a bubble in non-Newtonian fluids, a single bubble rising in shear-thinning fluids was experimentally studied using a high-speed camera. The effects of xanthan gum (XG) concentration and bubble diameter on bubble shape, trajectory, and terminal velocity were investigated. Results: Bubble terminal velocity increased with an increase in the bubble diameter and a decrease in XG concentrations. The increase rate of bubble terminal velocity varied with an increase in bubble diameter for the bubbles with different diameters and XG concentrations for the solutions with varying XG concentrations. For solutions with the same XG concentration, the Galilei and Eötvös numbers for a small bubble were relatively small but relatively large for a large bubble. Thus, the rise motion of a bubble in XG solutions becomes unsteady with an increase in bubble diameter and a decrease in XG concentrations. The unsteady characteristics of bubble motion decrease with an increase in the XG concentration of solutions. Conclusion: It was found that the influence of XG concentrations on bubble motion depends on bubble diameter since the magnitude of bubble diameter has an essential effect on the shear-thinning effect of solutions. An increase in bubble terminal velocity is mainly caused by an increase in buoyancy (i.e., bubble diameter) rather than a decrease in the apparent viscosity of solutions.

Analysis of Aviation Fuel Performance

Aviation fuels are jet fuels produced from crude oil and has specific physical and chemical properties. Analysis experiments were conducted for different samples of aviation fuel such as gas chromatography, color test, smoke point freezing point, and flash point. The sample of aviation fuel produced from Khartoum refinery used as control sample and other three samples took from air force with different storage period. Results showed that there is no change in color test of all samples, while the components differed in the GC test, where the control sample consisted of 30 compounds, compared with storage sample, which has 40 compounds. The total acidity and the relative mass of sulfur decreased. Meanwhile, there was a slight change in the boiling range and freezing point due to the decrease in viscosity. The results from smoke point test showed that, the smoke point increased from 29.6? in control sample to 37.3? in the storage sample. The electrical conductivity greatly decreased from 256 S/m in the control sample to 110 S/m in the storage sample. These results proved that the effect of storage time in the properties of aviation fuel.

Performance Evaluation of Rankiya (Grewia venusta) as a Polymer for Enhanced Oil Recovery-Polymer Flooding

Polymer Flooding is an enhanced oil recovery method where high-molecular-weight polymers are added into the injected water, in order to increase the viscosity of injection fluid, improve volumetric sweep efficiency, and finally increase the oil recovery factor. Most research studies focused on the use of partially hydrolysed polyacrylamide (HPAM), xanthan gum, SPG, HEC as flooding fluid. This work focused on investigating the potential of natural polymer - Grewia venusta plant tree in formulating flooding fluid for polymer flooding operation. The polymer was prepared from the mucilage extracted from the inner stem bark of Grewia venusta. Rheological characterization shows that the formulated Grewia venusta mucilage (GVM)-based flooding fluid maintained high viscosity under very high salinity, also exhibits shear thinning behaviour which obeys power law model with fluid behaviour index n = 0.32 and consistency index K= 6.3 at highest GVM concentration of 3000 ppm, similarly revealed that GVM-based flooding fluid was stable when subjected to high salinity of 130,000 ppm and temperature, up to 90 oC an inconsequential decrease in viscosity was experienced. These indicate its potential in enhancing oil recovery process. Core flooding analysis was carried out on an outcrop core sample with porosity and permeability of 26.1% and 218 mD respectively. Core flooding analysis revealed that: with increase in GVM concentration of 500, 750, 1000 and 2000 ppm oil recovered against time were 55.1%, 62.6%, 69.2% and 72.9% respectively, beyond 2000 ppm GVM concentration (optimum concentration), increase in polymer concentration did not bring about an increase in oil recovery, this finally resulted to an incremental recovery of 29% original oil in place (OOIP).