Analysis on the effect of nanographite obtained by an ultrasound technique in polypropylene compounds

2018 ◽  
Vol 33 (2) ◽  
pp. 254-269 ◽  
Author(s):  
Antonio Sanchez-Solis ◽  
Ricardo Perez Chavez ◽  
Octavio Manero Brito
Keyword(s):  
Particle Dispersion ◽  
Ultrasonic Waves ◽  
Ultrasound Technique ◽  
Melt Temperature ◽  
Graphene Layers ◽  
Melt Index ◽  
High Particle ◽  
Storage And Loss Moduli ◽  
Twin Screw ◽  
Flow Through

In this work, the effect of inclusion of nanographite particles in a polypropylene (PP) matrix is studied. Nanographite particles were obtained through ultrasound exfoliation from graphite upon using a water-based hydrophobically modified alkali-swellable emulsion (HASE) associative polymer as a surfactant. Results indicate that exfoliation renders particle size distribution ranging from 3 to 3000 nanometers. Nanographite was blended with PP through two extrusion processes: twin screw and single screw, the latter includes the coupling to a static-mixer head, to generate extensional flows. Concurrently, ultrasonic waves are applied to the molten flow through ultrasonic transducers attached to the mixing head, which induces high particle dispersion and good particle distribution in the polymer matrix. It was found that at HASE concentration of 5% by weight and sonication time of 14 days (period of the exfoliation process), optimum tensile properties of the compound were achieved. Also, with respect to the PP matrix, the rate of thermal degradation decreased from 2.1 (PP) to 1.9 (% °C−1), melt temperature ranged from 442°C (PP) to 396°C, and melt index decreased from 7.4 (PP) to 6.2 (g/10 min). Raman spectroscopy confirmed the exfoliation process, rendering sizes ranged from graphite particles of few graphene layers to micron-sized particles. Rheological measurements of the compounds revealed that the extrusion-ultrasound process influences the viscosity, storage, and loss moduli. The dispersion and distribution of nanoparticles improved the electromagnetic radiation shield (approximately 35%). The dielectric constant changed from 2.21 (pristine PP) to 9.02 for the compounds, which enables a good level of electrostatic charge dissipation.

scholarly journals In-Line Rheo-Optical Investigation of the Dispersion of Organoclay in a Polymer Matrix during Twin-Screw Compounding

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2128
Author(s):  
Paulo F. Teixeira ◽  
José A. Covas ◽  
Loïc Hilliou
Keyword(s):  
Local Heating ◽  
Polymer Nanocomposite ◽  
Structural Rearrangement ◽  
Particle Dispersion ◽  
Optical Investigation ◽  
Twin Screw Extrusion ◽  
Clay Particles ◽  
Clay Dispersion ◽  
Screw Extrusion ◽  
Twin Screw

The dispersion mechanisms in a clay-based polymer nanocomposite (CPNC) during twin-screw extrusion are studied by in-situ rheo-optical techniques, which relate the CPNC morphology with its viscosity. This methodology avoids the problems associated with post extrusion structural rearrangement. The polydimethylsiloxane (PDMS) matrix, which can be processed at ambient and low temperatures, is used to bypass any issues associated with thermal degradation. Local heating in the first part of the extruder allows testing of the usefulness of low matrix viscosity to enhance polymer intercalation before applying larger stresses for clay dispersion. The comparison of clay particle sizes measured in line with models for the kinetics of particle dispersion indicates that larger screw speeds promote the break-up of clay particles, whereas smaller screw speeds favor the erosion of the clay tactoids. Thus, different levels of clay dispersion are generated, which do not simply relate to a progressively better PDMS intercalation and higher clay exfoliation as screw speed is increased. Reducing the PDMS viscosity in the first mixing zone of the screw facilitates dispersion at lower screw speeds, but a complex interplay between stresses and residence times at larger screw speeds is observed. More importantly, the results underline that the use of larger stresses is inefficient per se in dispersing clay if sufficient time is not given for PDMS to intercalate the clay galleries and thus facilitate tactoid disruption or erosion.

scholarly journals Contamination of Trichloroethylene in Drinking Water System and Its Degradation

2012 ◽  
Vol 3 ◽  
pp. 13-17 ◽  
Author(s):  
Devi Lal Adhikari ◽  
Chikashi Sato ◽  
Shobha Kanta Lamichhane
Keyword(s):  
Drinking Water ◽  
Titanium Dioxide ◽  
Ultraviolet Light ◽  
Water System ◽  
Ultrasonic Waves ◽  
Produce Water ◽  
Drinking Water Standard ◽  
Drinking Water System ◽  
Flow Through ◽  
System Water

Photolysis and sonolysis of trichloroethylene (TCE) in water was investigated using a cup-horn, flow-through reactor system. Water containing titanium dioxide was deliberately contaminated with TCE. These solutions were irradiated with ultraviolet light (UV) and ultrasonic waves (US). The decrease in the TCE concentration was observed in water under both US and UV treatments. Present findings declare that the use of UV and US decreased the TCE concentration. With the reactor specifications used, the photolysis and sonolysis processes can produce water meeting the drinking water standard (MCLs of 5?g/L) for TCE.The Himalayan PhysicsVol. 3, No. 32012Page : 13-17

scholarly journals Mechanical spectroscopy of insect swarms

2019 ◽  
Vol 5 (7) ◽  
pp. eaaw9305 ◽  
Author(s):  
Kasper van der Vaart ◽  
Michael Sinhuber ◽  
Andrew M. Reynolds ◽  
Nicholas T. Ouellette
Keyword(s):  
Information Flow ◽  
Collective Behavior ◽  
Mechanical Spectroscopy ◽  
Bulk Materials ◽  
Animal Groups ◽  
Environmental Perturbations ◽  
Storage And Loss Moduli ◽  
Social Animals ◽  
In The Wild ◽  
Flow Through

Social animals routinely form groups, which are thought to display emergent, collective behavior. This hypothesis suggests that animal groups should have properties at the group scale that are not directly linked to the individuals, much as bulk materials have properties distinct from those of their constituent atoms. Materials are often probed by measuring their response to controlled perturbations, but these experiments are difficult to conduct on animal groups, particularly in the wild. Here, we show that laboratory midge swarms have emergent continuum mechanical properties, displaying a collective viscoelastic response to applied oscillatory visual stimuli that allows us to extract storage and loss moduli for the swarm. We find that the swarms strongly damp perturbations, both viscously and inertially. Thus, unlike bird flocks, which appear to use collective behavior to promote lossless information flow through the group, our results suggest that midge swarms use it to stabilize themselves against environmental perturbations.

Study of a screw rotor with different stocks and leads for a twin-screw multiphase pump

2009 ◽  
Vol 223 (11) ◽  
pp. 2637-2645 ◽  
Author(s):  
F Cao ◽  
T Gao ◽  
J Jiao ◽  
T Pan ◽  
Z Xing
Keyword(s):  
Dominant Role ◽  
Contour Plot ◽  
Leakage Flow ◽  
Normal Height ◽  
Plot Analysis ◽  
Rotor Profile ◽  
Twin Screw ◽  
Screw Rotor ◽  
Flow Through ◽  
Multi Phase

Rotor profile generation and geometry characteristics play a dominant role in developing twin-screw multi-phase pumps. The aim of this work is to present mathematical procedures to calculate screw rotor profile generation, design rotor cutter tools, and rotor geometry characteristics with given stocks for twin-screw multi-phase pumps. Analyses of the profile generation of a screw rotor for a multi-phase pump are carried out. The resulting rotor profile with different stocks is developed on the basis of the calculation of the forming cutter tool profile. An iso-height contour plot is presented for describing the shape and size of the overlapped cavity of the rotors. By inspecting the iso-height contour plot, analysis of all the possible leakage flow through the inter-lobe clearance is performed. According to the iso-height contour plot, the blowhole provides the major leakage path for the basic chambers through the overlapped cavity. The minimum normal height of the overlapped cavity has a linear relationship with the stock. The larger stocks lead to greater leakage and reduce pump performance. The leakage flow through the overlapped cavity will be aggravated and the performance of the twin-screw multi-phase pump will decline with the increasing lead of the screw rotor.

Effects of an Injection Angle of Water Pipes in an Ultrasonic Cleaning Tank on Particle Disposal Capability

2014 ◽  
Vol 931-932 ◽  
pp. 1134-1138
Author(s):  
Kitikorn Wongmanee ◽  
Sujin Bureerat ◽  
Julaporn Benjapiyaporn
Keyword(s):  
Fluid Dynamic ◽  
Water Injection ◽  
Flow Simulation ◽  
Particle Dispersion ◽  
Ultrasonic Waves ◽  
Two Phase ◽  
Injection Angle ◽  
Ultrasonic Cleaning ◽  
Water Pipes ◽  
Horizontal Tubes

This paper presents simulation of particle dispersion in an ultrasonic cleaning tank.Contaminants removed from work-pieces by means of ultrasonic waves need to be disposed from the tank during the cleaning process. This is achieved by using water injection from horizontal tubes placed at the bottom inside the tank. It is expected that injection angles could affect the performance of particle disposal. The two-phase flow simulation is adopted to predict disposal capability while the computational fluid dynamic is carried out by means of finite volume analysis. Simulation results of particle dispersion in the tank with various injection angles are conducted, displayed, and concluded.

Particle dispersion in a vertical round sudden-expansion flow

1992 ◽  
Vol 341 (1662) ◽  
pp. 411-442 ◽  
Keyword(s):  
Recirculation Zone ◽  
Probability Distributions ◽  
Mean Transit Time ◽  
Fluid Velocity ◽  
Particle Dispersion ◽  
Sudden Expansion ◽  
Stream Line ◽  
Phase Doppler Anemometry ◽  
Flow Through ◽  
Time Required

The dispersion of glass beads in an air flow through sudden step expansions in the direction of gravity has been investigated with phase-Doppler anemometry, which provided measurements of the velocity, flux and concentration characteristics. The purpose was to quantify the effect of increasing the air velocity over a factor of 5 for bead diameters of 40 µm and 80 µm and two expansion diameter ratios, 3.33 and 5, and at mass loadings of beads up to 90% of the air mass flow-rate. The results showed that the beads dispersed into the recirculation zone in the lee of the step by interaction with eddies characterized by length and velocity scales of the order of the expansion step height and the downstream area-averaged velocity. Particle dispersion into the recirculation zone was reduced when the bead mean transit time across the recirculation zone was shorter than the bead relaxation time, defined as the time required for a motionless bead suddenly exposed to a constant velocity fluid stream to reach 63% of its surrounding fluid velocity. Also the centrifuging effect, caused by the mean stream line curvature of the recirculation zone, could reduce particle dispersion into the recirculation zone, when its characteristic dimensionless group was less than unity. Beads, because of their mass, left the recirculation zone by sliding down the wall and past the air reattachment point or near the step, giving rise to bimodal probability distributions of velocity.

scholarly journals Effect of fracture orientation on ultrasonic wave signatures

2020 ◽  
Vol 205 ◽  
pp. 03008
Author(s):  
Bijay KC ◽  
Ehsan Ghazanfari
Keyword(s):  
Ultrasonic Wave ◽  
Oil And Gas ◽  
Critical Role ◽  
Ultrasonic Waves ◽  
S Waves ◽  
Fracture Orientation ◽  
Confining Pressures ◽  
Flow Through ◽  
Series Of Experiments ◽  
Oil And Gas Reservoir

Fluid flow through low-permeable rock masses is dominated by transport through discontinuities such as fractures, faults, and joints present in the rock. These discontinuities are beneficial for some geo-resources such as geothermal, oil and gas reservoir, but detrimental for other applications such as CO2 storage and hazardous waste isolation. Fracture orientation plays a critical role during the design of the geo-resources. Often times, ultrasonic waves are used in the field to locate and characterize the fractures. In this study, the effect of fracture orientation (0° to 90°) on ultrasonic wave signatures was investigated by conducting a series of experiments on a granite rock with a longitudinal fracture under confining pressures of 15, 30, and 45 MPa. Ultrasonic wave signatures during the experiment were collected using the ultrasonic transducers embedded in the core holders that were attached to the two ends of the specimen. Results indicated sensitivity of the ultrasonic wave velocities, waveforms, and amplitudes (cross-polarized S-waves) to the fracture orientation.

Study of the Discharge Pressure Pulsation Within Twin Screw Compressors

2001 ◽  
Author(s):  
Ziwen Xing ◽  
Xueyuan Peng ◽  
Xiaojun Zhang ◽  
Tiansheng Cui
Keyword(s):  
Gas Flow ◽  
Pressure Pulsation ◽  
Theoretic Analysis ◽  
One Dimensional ◽  
Flow Equations ◽  
Twin Screw ◽  
Flow Through ◽  
The One ◽  
Discharge Pressure ◽  
Unsteady Gas Flow

Abstract Even in the absence of valves, flow through the discharge port of a screw compressor is oscillatory in nature. This unsteady but periodic flow variation at the discharge port excites the pressure pulsation. In this paper, the one-dimensional unsteady gas flow equations describing the discharge pressure pulsation are established, which allow for the effects of the viscosity friction and heat transfer between the gas and the pipe, and the boundary conditions of discharge pressure pulsation are considered. With Two-Step Lax-Wendroff scheme used, the one-dimensional unsteady gas flow equations are solved. In order to verify the theoretic analysis, the discharge pressure pulsation at variable working conditions is measured. It is shown that the model established in this paper is valid for getting a better understanding of the mechanism governing the behavior of the pressure pulsation in discharge pipe. It is found that the most important factor that affects the discharge pressure pulsation is the pressure difference between the actual discharge pressure and the design discharge pressure.

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