Decrease In Flow Index Research Articles

Study of mechanical and rheogical properties of HDPE/iPP cross-linking polymer blends

The rapidly developing subject of polymer mix design presents prospects for the creation of materials with precisely customised qualities. It's crucial to comprehend the morphology that results from blending immiscible polymers for obtaining the required mechanical qualities. This study explores the complex interactions between structure and characteristics in both cross-linked and unmodified blends of HDPE and iPP. Our study provides important new information by combining mechanical testing and rheological evaluations. It is observed that materials that are cross-linked have a significantly higher viscosity, which suggests the establishment of a three-dimensional network and improved stability. Furthermore, HDPE exhibits enhanced behaviour after crosslinking. After crosslinking, the melt flow index decreases, indicating increased resistance to flow and deformation because more interchain links are formed. Higher PP concentration in unmodified blends results in greater flexibility and ductility, but cross-linking causes rigidity. On the other hand, cross-linking improves flexibility by reducing rigidity in mixes with a lower iPP concentration. Additionally, the combination of iPP and crosslinking agents results in a significant improvement in mechanical strength, which reinforces structural integrity. Crosslinking also improves impact resistance, making the materials appropriate for uses requiring strong performance in demanding circumstances.

An investigation of endometrial vascularity in normally menstruating women and those in other physiological states using 3D ultrasound imaging.

This study aimed to determine the normal vasculature indices of the endometrium and to correlate them with those in various physiological states. Women undergoing ultrasound at the Feto-Maternal Center, Qatar in 2020-2021 as part of their gynecologic evaluation were enrolled into the study. They were divided into those with normal menses and no additional pathology, those following spontaneous miscarriage, postpartum and menopausal. Three-dimensional (3D) evaluation of the endometrial vasculature was done and the parameters quantified included vascularization index (VI), flow index (FI), vascularization flow index (VFI), endometrial thickness, endometrial volume and uterine volume. JASP, an open-source statistical analysis software, was used for analysis and an independent t-test to compare the vascularity indices. A multivariate regression analysis was also done to look at the factors affecting the endometrial vascular indices within the luteal phase. A total of 461 women were studied: 122 in the follicular phase, 199 in the luteal phase, 90 after a spontaneous miscarriage, 29 postpartum, and 16 menopausal. The vascularity indices were highest after miscarriage and lowest postnatally. There were no significant effects of age, gravida, para, or abortions on VI and VFI. However, there was a significant positive effect of age on FI (P = 0.019) There was a significant increase in endometrial volume and thickness in the luteal phase as compared to follicular phase (P < 0.01), but there was no difference in the vascularity indices. The uterine and endometrial volume in the postnatal group were nearly double that of the luteal group (P value <0.01 and 0.014, respectively). There was a significant decrease in flow index in the postnatal group compared to the luteal group (P < 0.01), suggesting low flow intensity in the postnatal group. Endometrial vascular indices measured using 3D Doppler can be used to determine normal vascular indices and vary with physiological states such as after miscarriages, postnatally and in the menopausal states.

Investigation of copper reinforced Acrylonitrile Butadiene Styrene and Nylon 6 based thermoplastic polymer nanocomposite filaments for 3D printing of electronic components

Fused Deposition Modeling (FDM) is one of the most efficient and frequently used methods for the development of biomedical implants, bio-sensors, and customized products. In the FDM process, the filament made of polymers or composites is passed through a nozzle in which heaters are provided to melt the feedstock filament. The addition of copper particles to the polymer filament would enhance its thermal and electrical conductivity which finds vast applications in the development of sensors and other electronic components. Thus, it is obligatory to maintain the melt flow index of the filament following the size of the nozzle and the speed of the filament through the nozzle. The virgin polymer materials used as feedstock filament have an appropriate melt flow index (MFI), but the rheological properties of the polymer composites are not defined. This study focuses on the calculation and measurement of the melt flow rate of copper reinforced with acrylonitrile butadiene styrene (ABS) and nylon 6 thermoplastic matrices using fused deposition modeling. The copper particles of different sizes (149 μm, 74 μm, and 37 μm) were added in ABS and nylon 6 thermoplastic matrices to study the mechanical properties. The melt flow rate has been checked for different concentration ratios varying from 1% to 10% of copper reinforcements. The impact of single, double, and triple-sized copper particles on MFI has been investigated. It has been found that with an increase in copper powder concentration in nylon 6, the melt flow index decreases. On the other hand, the MFI initially increases up to 6% and further decreases by adding more particulates of copper powder in ABS. The surface topography of copper reinforced with different percent-compositions of ABS and nylon 6 based polymer composites have been carried out by using scanning electron microscopy.

Simulation and Verification of Hydraulic Performance and Energy Dissipation Mechanism of Perforated Drip Irrigation Emitters

Drip irrigation has become an application trend of water-saving irrigation technology due to its excellent water-use efficiency. However, the energy dissipation form of the commonly used labyrinth channel is relatively simple, and the corresponding energy dissipation mechanism research is inadequate. This article proposes a new kind of channel structure of drip irrigation emitters based on the structure of scalariform perforation plates in plant xylem vessels. We establish a total of 16 sets of orthogonal structure schemes. Using numerical simulation and physical experiments, the hydraulic performance and energy dissipation mechanism of the perforated drip irrigation emitters (PDIE) are studied. The results show that the flow index of PDIE is 0.4665–0.5266. The hydraulic performance of PDIE in the high-pressure zone is the best, and the flow index is 0.4665–0.5046. As the pressure increases, the velocity of the flow of the upper perforation increases rapidly, the flow ratio decreases, the flow index decreases, and the hydraulic performance improves. To further verify the energy dissipation mechanism, a lower flow ratio and a better hydraulic performance were obtained through appropriately expanding the upper part of the upper perforation inlet to the channel boundary. The research sheds new insights for optimizing the hydraulic performance of PDIE. Results reported here provide a theoretical basis for the structural design of drip irrigation emitters and the energy dissipation mechanism research.

РОЗРОБКА АНТИСТАТИЧНИХ І НАПІВПРОВІДНИКОВИХ КОМПОЗИЦІЙ ПОЛІЕТИЛЕН/ПОЛІАНІЛІН ТА ПОЛІВІНІЛХЛОРИД/ПОЛІАНІЛІН

The effect of the polyaniline content on the mechanical, rheological and electrical properties of polyethylene and polyvinylchloride compositions for the production of antistatic and semiconductive materials was established. Samples of polymer composites were obtained in two stages: 1) mixing of components in a mixer type "disk in disk"; 2) pressing into films by the method of "hot pressing." Tensile strength, relative elongation, melt flow index and specific volume electrical resistance of the compositions were investigated by standard methods. It was found that an increase in the volume content of polyaniline in the polyethylene and polyvinylchloride matrix leads to a monotonic decrease in the melt flow index, as well as tensile strength and relative elongation. At the same time, there is a significant decrease in the specific volume electrical resistance in polyethylene and polyvinylchloride composite films, which contain up to 30% vol. of polyaniline. The reduction of the tensile strength and the relative elongation of films from compositions containing up to 30% vol. of polyaniline. This is due to the decrease in the viscosity of the melt-filled compositions, as evidenced by the decrease in the flow index of the melt polyethylene compositions from 3 to 2 g / 10 min, and polyvinylchloride – from 13 to 3 g / 10 min. Specific volume electrical resistance naturally decreases with increasing volume concentration of the filler in ranges from 1014 to 102 Ohm ∙ m for polyethylene compositions and from 1010 to 101 Ohm ∙ m for polyvinylchloride compositions. The developed polyethylene and polyvinylchloride compositions filled with polyaniline can be used for the production of polymer products with antistatic and semiconductive properties.

Control of the effects of the concentration on the viscoelastic behavior of the aqueous Polyethylene-Oxide solution

It is established that the rheological properties of polyethylene oxide solutions are related to the concentration, molecular weight, nature of the solvent, external stresses such as temperature and pressure and microstructural interactions. The main objective of this study is to carry out the effect of the concentration of aqueous PEO solutions on their rheological behavior. In this context, we consider quasi-stationary, transient and oscillatory flow regimes for three values of concentrations (250 ppm, 500 ppm and 1000 ppm). Except the case where the solution is Binghamian (250 ppm), we denote that for quasi-stationary mode, the observed behaviors correspond to a rheofluidifying fluids with yield stress. The model adapted from Rheowin Software is Herschel-Bulkley for whicha yield stress and consistency increases and a flow indexdecreases when the concentration increases. The studies of these solutions under transient and subsequently under oscillating conditions are made to specify their viscoelastic properties. For a concentration less than 500 ppm the viscoelastic nature is described by the Maxwell model and by the Jeffrey model for a concentration of 1000 ppm. Otherwise, and for the oscillating test, the determination of the evolution of the critical frequency fc (for which the conservation factor G ʹand the loss factor Gʹ ʹare comparable) as a function of the concentration consolidates the actual control protocols of PEO aqueous solutions and allows to optimize the processes of their use in industrial environment.

Analytical solution by Laplace-ritz variational method for non-Newtonian nanofluid inside a circular tube

In this paper, laminar developing forced convection flow of a non-Newtonian nanofluid inside a circular tube, subjected to a constant heat flux at the wall, is analytically and numerically investigated. The nanofluid is composed of CuO nanoparticles and the non-Newtonian base fluid of 0.5 wt % aqueous solution of Carboxymethyl Cellulose (CMC). By taking into account the effect of viscous dissipation, a methodology based on a variational Ritz approach combined with Laplace transform technique is presented for a non-Newtonian fluid described by the power-law model. The effects of Brinkman numbers (Br), power low index (n) and nanoparticle concentrations (φ) on the developing temperature fields and the local Nusselt number were examined. The exact solution obtained was validated with the results obtained numerically by the Control Volume Method and with the particular cases of conventional fluids (φ = 0) and non-viscous dissipation effect (Br = 0) available in literature. The results obtained are given graphically in term of Nusselt number showing the effects of Brinkman, Peclet number, nanoparticles concentration (φ) and power low index (n). It is shown that in the fully developed region, Nusselt number has a fixed asymptotic value depending of Br number. At a fixed Brinckman number, the asymptotic Nusselt number increases substantially as the flow index decreases. Besides, it is seen that the incrusting of nanoparticle concentration has a positive effect on heat transfer that the Nusselt number distributions are enhanced by increasing the volume fraction of CuO due to the augmentation of thermal conductivity of the resulting fluid and an asymptotic value is independent of Peclet number.

Short communication: Effect of whey protein addition and transglutaminase treatment on the physical and sensory properties of reduced-fat ice cream

The effects of whey protein addition and transglutaminase treatment, alone and in combination, on the physical and sensory properties of reduced-fat ice cream were investigated. Adding whey protein with or without enzyme treatment decreased melting rate, overrun, and hardness of the reduced-fat ice cream; however, the enzyme-treated sample had a higher melting rate and overrun and softer texture. Whey protein-fortified samples showed higher melting resistance, but lower overrun and firmer texture compared with the enzyme-treated sample without added whey protein. Whey protein addition with or without transglutaminase treatment caused an increase in apparent viscosity and a decrease in flow index of the reduced-fat ice cream; nevertheless, the flow behavior of full-fat sample was most similar to the enzyme-treated reduced-fat sample with no added whey protein. Descriptive sensory analyses showed that neither whey protein addition nor transglutaminase treatment significantly influenced the flavor and odor of reduced-fat ice cream, but they both noticeably improved the color and texture of the final product. The results of this study suggest that whey protein addition with transglutaminase treatment improves the physical and sensory properties of reduced-fat ice cream more favorably than does whey protein addition or transglutaminase treatment alone.

A Model for Line-Contact EHL Problems—Consideration of Effects of Navier-Slip and Lubricant Rheology

The coupled extended Reynolds (which includes the effects of Navier-slip and flow rheology), elasticity deformation, and the load equilibrium (under a constant load condition) equations are solved simultaneously for the EHL problems. Results show that as the slip length increases or the flow index decreases, the film thickness decreases, the central pressure increases, the pressure spike decreases, the maximum pressure switches from the pressure spike to the central pressure, and the film shape and pressure profiles moves gradually toward the outlet. A proper combination of flow rheology and slip length could fulfill some preferred EHL conditions.

Study on rheological behaviour of selfcrosslinkable acrylate emulsion with nanosilica sol by blending

A study on blending self-crosslinkable acrylate emulsion with nanosilica sol has been made to improve the paint film properties. Fourier transform infrared, differential scanning calorimetry and SEM are employed to characterise the film prepared by blending polyacrylic emulsion with nanosilica sol. The results of the rheological property show that the blended emulsions containing different silica sol contents are pseudoplastic fluid, and the apparent viscosity, consistency factor and zero shear viscosity increase in accordance with the content of the silica sol, but the emulsion flow index decreases. After being laid for 2 days, the apparent viscosity, consistency coefficient and zero shear viscosity of the emulsion increase, but the flow index is decreased in comparison with the emulsion with the same amount of silica sol without laying.

Structure‐rheology responses of polylactide/calcium carbonate composites

AbstractPolylactide (PLA) and calcium carbonate (CaCO3) were melt blended using a twin‐screw extruder. The morphology of PLA/CaCO3 composites was observed by scanning electronic microscopy. The linear and nonlinear shear rheological behaviors of PLA/CaCO3 melts were investigated by an advanced rheology expended system. The results show that the CaCO3 particles are evenly dispersed in the PLA matrix. The incorporation of low CaCO3 content (&lt;20%) causes the reduction of the storage moduli, loss moduli, and dynamic viscosities whereas high CaCO3 content (&gt;30%) leads to the increase of the storage moduli, loss moduli, and dynamic viscosities. The composites with high CaCO3 content show pseudo‐solid‐like behaviors at low frequency. High CaCO3 content also results in a significant increase of flow activation energy and a dramatic decrease of flow index n, which is in consistent with the more serious shear‐thinning tendency of high‐filled PLA composites melts. The particular rheological responses might be attributed to the formation and destruction of the percolating network. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Melt rheology of polylactide/poly(butylene adipate- co-terephthalate) blends

Polylactide (PLA) and poly(butylene adipate- co-terephthalate) (PBAT) were melt blended using a twin-screw extruder. The phase morphology of PLA/PBAT blends was observed by scanning electronic microscopy (SEM). The linear and non-linear shear rheological behaviors of PLA/PBAT melts were investigated by an advanced rheology expended system (ARES). The results show that PLA/PBAT blend is a kind of immiscible, two-phase system where PBAT disperses evenly in PLA matrix. Linear viscoelastic limits of PLA/PBAT melts are smaller than that of neat PLA melt. At lower frequencies, storage moduli ( G′) of PLA/PBAT melts increase with PBAT content. PBAT content has no significant effect on loss moduli ( G′′) of PLA/PBAT melts, but the relaxation moduli of the melts increase with the introduction of PBAT. At the same time, the incorporation of PBAT results in a gradual increase of the melt viscosity and a decrease of flow activation energy. Besides PBAT causes a decrease of flow index n, which is in conformity with the more serious shear-thinning tendency of PLA/PBAT melts.

The influence of texture improver type and its addition level on rheological properties of goat’s milk yogurt

Set yogurt from goat?s milk with addition of two texture improvers DSE 6693 and DSE 6694 from NZMP New Zealand, added in the amount of 1, 2and 3% and control yogurt without addition of texture improvers were produced. In yogurt determined sensory quality, pH, apparent viscosity and rheological properties. Flow curves obtained for produced yogurts were described by three rheological models: Ostwald de Waele, Herschel-Bulkley (H-B) and Casson. Addition of texture improver caused an increase in total solids and total protein content of milk for yogurt. Yogurt with texture improvers gave better sensory quality than control yogurt. The yogurt with 1% addition of DSE 6693 and with 2% addition of DSE 6694 had the best sensory quality. The increase in addition level of texture improvers caused an increase in apparent viscosity, consistency coefficient K, yield stress (except H-B model) and deviation from Newtonian flow (decrease of flow index n). Effect of type of improver was rather negligible, whereas its level addition considerably influenced the evaluated rheological parameters.

Unsteady flow of a dusty conducting non-Newtonian fluid through a pipe

In this paper, the unsteady flow of a dusty viscous incompressible electrically conducting non-Newtonian power-law fluid through a circular pipe is investigated. A constant pressure gradient in the axial direction and a uniform magnetic field directed perpendicular to the flow direction are applied. The particle phase is assumed to behave as a viscous fluid. A numerical solution is obtained for the governing nonlinear momentum equations using finite differences. The effects of the magnetic-field parameter Ha, the non-Newtonian fluid characteristics (the flow index n), and the particle-phase viscosity β on the transient behavior of the velocity, volumetric flow rates, and skin friction coefficients of both fluid and particle phases are studied. It is found that all the flow parameters for both phases decrease as the magnetic field increases or the flow index decreases. On the other hand, increasing the particle-phase viscosity increases the skin friction of the particle phase, but decreases the other flow parameters. PACS No.: 47.50.+d

Advanced Study on Non-Newtonian Flow of Polymer Melts in Extrusion Die of Plastic Net

Abstract Broken section method is extended to analyze theoretically non-Newtonian flow of polymer melts with power law in the extrusion die of plastic net, in consideration of transversal drag action by die rotation. Die lip having overlap profile of semi-circle is broken into many sections, perpendicular to rotating boundary line. Computer approach is applied to analyze numerically the flow in each broken section. The flow isovels in discharge direction are indicated in various values of flow index and overlap ratio of upper and lower die lips. With increasing non-Newtonian behaviour, the profiles of the isovels in discharge direction are flattened and the area of the isovels of 0.9 increases to shift its location downwards. The flow isovels in rotating drag direction is plotted only in the case of half overlap ratio. With the decrease of flow index, the positive velocity profile in drag direction is flattened for larger area to cancel the sharp negative velocity near rotating drag boundary. Volumetric R...