The Experts below are selected from a list of 24510 Experts worldwide ranked by ideXlab platform
Lihsheng Turng - One of the best experts on this subject based on the ideXlab platform.
-
an improved technique for dispersion of natural graphite particles in thermoplastic polyurethane by sub critical Gas assisted processing
Composites Science and Technology, 2019Co-Authors: An Huang, Hankun Wang, Thomas Ellingham, Xiangfang Peng, Lihsheng TurngAbstract:Abstract Dispersing fillers uniformly is the main technological challenge when considering nanocomposites. In this paper, a novel and efficient sub-critical Gas-assisted processing (SGAP) technique is explored—an environmentally benign process that utilizes compressed CO2 to help effectively disperse aggregated natural graphite particles (NGPs) (3 wt%) in a thermoplastic polyurethane (TPU) matrix. A twin-screw extruder (TSE) equipped with a simple CO2 injection unit consisting of a standard Gas Cylinder, regulator, valve, and metal hose is employed for the melt mixing. Results from the structural, thermal, rheological, mechanical, microcellular injection molding, dielectric, and thermal conductive properties of the SGAP pellets, in addition to the resultant TPU/NGP nanocomposites, confirmed significantly improved dispersion compared to those obtained via conventional melt blending in the TSE. This technique offers a simple, cost-effective approach to the large-scale production of high-performance polymer nanocomposites without the requirement for complicated processing steps such as supercritical fluid (SCF) processes or chemical treatments.
-
sub critical Gas assisted processing using co2 foaming to enhance the exfoliation of graphene in polypropylene graphene nanocomposites
Polymer, 2017Co-Authors: Thomas Ellingham, Lukas Duddleston, Lihsheng TurngAbstract:Abstract Polypropylene (PP) and graphene nanoparticles (GNPs) were mixed in a twin-screw extruder equipped with a simple CO 2 injection unit consisting of a standard Gas Cylinder, a regulator, a valve, and a metal hose. Nanocomposites were produced with a 0.5% by weight GNP loading level. The addition of CO 2 into the melt at pressures below the supercritical point allowed for foaming to occur within the barrel of the extruder and upon exiting from the die. Foaming introduces an equibiaxial flow on the surface of the expanding bubbles. This extensional flow imparts a stress greater than the shear case alone, aiding in the breakup of GNP agglomerates. Samples processed with sub-critical CO 2 showed increased exfoliation and dispersion as observed via electron microscopy, thermal analysis, Raman spectroscopy, and X-ray diffraction. This sub-critical Gas-assisted processing (SGAP) method was introduced as an alternative to supercritical fluid-assisted processing.
Sanjeev Chandra - One of the best experts on this subject based on the ideXlab platform.
-
producing molten metal droplets smaller than the nozzle diameter using a pneumatic drop on demand generator
Experimental Thermal and Fluid Science, 2013Co-Authors: Mehdi Raessi, A Amirzadeh, Sanjeev ChandraAbstract:Abstract A pneumatic droplet generator to produce molten metal droplets smaller than the nozzle diameter is described. The generator consists of a heated Cylinder in which a cavity is machined. A nozzle is fit into a stainless steel nozzle holder and attached to the bottom plate of the generator. The system is connected to a Gas Cylinder through a solenoid valve. Opening the valve for a preset time creates a pulse of alternating negative and positive pressure in the Gas above the surface of the molten metal, and a droplet is ejected through the nozzle. The effect of various parameters such as the ejection frequency, nozzle diameter, pulse width and secondary Gas flow on droplet formation is investigated. This method made it possible to produce droplets as small as 60% the nozzle diameter. An approximate analytical method is studied to understand the liquid behavior within the nozzle, estimate the droplet size, and investigate the effect of the secondary Gas flow pressure on droplet diameter.
-
Producing droplets smaller than the nozzle diameter by using a pneumatic drop-on-demand droplet generator
Experiments in Fluids, 2008Co-Authors: A. Amirzadeh Goghari, Sanjeev ChandraAbstract:A pneumatic droplet generator to produce water/glycerin droplets smaller than the nozzle diameter is described. The generator consists of a T-junction with a nozzle fit into one opening, the second opening connected to a Gas Cylinder through a solenoid valve and the third connected to a length of steel tubing. The droplet generator is filled with liquid. Opening the valve for a preset time creates a pulse of alternating negative and positive pressure in the Gas above the surface of the liquid, ejecting a single droplet through the nozzle. Droplet formation was photographed and the pressure variation in the droplet generator recorded. The effect of various experimental parameters, such as nozzle size, pressure pulse width and liquid properties on droplet formation was investigated. Small droplets could not be generated when liquid viscosity was too low or too high. For pure water, droplet diameters were several times that of the nozzle. Using more viscous glycerin mixtures, droplets with diameters as small as 65% of the nozzle diameter could be produced.
-
producing molten metal droplets with a pneumatic droplet on demand generator
Journal of Materials Processing Technology, 2005Co-Authors: Stewart Xu Cheng, Sanjeev ChandraAbstract:Abstract A pneumatic droplet generator to produce molten metal droplets on demand is described. It consists of a cylindrical heated chamber with a small nozzle set into its bottom surface, connected to a Gas Cylinder through a solenoid valve. Opening and closing the valve for approximately 10–12 ms imposes a pressure pulse on the molten metal in the chamber, ejecting a single droplet through the nozzle. Pressure in the chamber then drops rapidly as Gas escapes through a vent hole and draws back liquid from the nozzle, preventing more droplets from escaping. By adjusting the duration of the pressure pulse we can obtain a single droplet each time a pulse is applied. Droplets of molten indium, tin, lead, and zinc were produced with the droplet generator. Drops with diameters ranging from 0.17 to 0.60 mm were formed using nozzles 0.076–0.254 mm in diameter. It was important to keep the oxygen content in the test chamber below 150 ppm, otherwise metal oxidized as it emerged and blocked the nozzle. By coordinating droplet formation with the movement of an x – y stage placed beneath the droplet generator, droplets could be place in arbitrary patterns such as a straight line, circle, triangle or grid.
Thomas Ellingham - One of the best experts on this subject based on the ideXlab platform.
-
an improved technique for dispersion of natural graphite particles in thermoplastic polyurethane by sub critical Gas assisted processing
Composites Science and Technology, 2019Co-Authors: An Huang, Hankun Wang, Thomas Ellingham, Xiangfang Peng, Lihsheng TurngAbstract:Abstract Dispersing fillers uniformly is the main technological challenge when considering nanocomposites. In this paper, a novel and efficient sub-critical Gas-assisted processing (SGAP) technique is explored—an environmentally benign process that utilizes compressed CO2 to help effectively disperse aggregated natural graphite particles (NGPs) (3 wt%) in a thermoplastic polyurethane (TPU) matrix. A twin-screw extruder (TSE) equipped with a simple CO2 injection unit consisting of a standard Gas Cylinder, regulator, valve, and metal hose is employed for the melt mixing. Results from the structural, thermal, rheological, mechanical, microcellular injection molding, dielectric, and thermal conductive properties of the SGAP pellets, in addition to the resultant TPU/NGP nanocomposites, confirmed significantly improved dispersion compared to those obtained via conventional melt blending in the TSE. This technique offers a simple, cost-effective approach to the large-scale production of high-performance polymer nanocomposites without the requirement for complicated processing steps such as supercritical fluid (SCF) processes or chemical treatments.
-
sub critical Gas assisted processing using co2 foaming to enhance the exfoliation of graphene in polypropylene graphene nanocomposites
Polymer, 2017Co-Authors: Thomas Ellingham, Lukas Duddleston, Lihsheng TurngAbstract:Abstract Polypropylene (PP) and graphene nanoparticles (GNPs) were mixed in a twin-screw extruder equipped with a simple CO 2 injection unit consisting of a standard Gas Cylinder, a regulator, a valve, and a metal hose. Nanocomposites were produced with a 0.5% by weight GNP loading level. The addition of CO 2 into the melt at pressures below the supercritical point allowed for foaming to occur within the barrel of the extruder and upon exiting from the die. Foaming introduces an equibiaxial flow on the surface of the expanding bubbles. This extensional flow imparts a stress greater than the shear case alone, aiding in the breakup of GNP agglomerates. Samples processed with sub-critical CO 2 showed increased exfoliation and dispersion as observed via electron microscopy, thermal analysis, Raman spectroscopy, and X-ray diffraction. This sub-critical Gas-assisted processing (SGAP) method was introduced as an alternative to supercritical fluid-assisted processing.
An Huang - One of the best experts on this subject based on the ideXlab platform.
-
an improved technique for dispersion of natural graphite particles in thermoplastic polyurethane by sub critical Gas assisted processing
Composites Science and Technology, 2019Co-Authors: An Huang, Hankun Wang, Thomas Ellingham, Xiangfang Peng, Lihsheng TurngAbstract:Abstract Dispersing fillers uniformly is the main technological challenge when considering nanocomposites. In this paper, a novel and efficient sub-critical Gas-assisted processing (SGAP) technique is explored—an environmentally benign process that utilizes compressed CO2 to help effectively disperse aggregated natural graphite particles (NGPs) (3 wt%) in a thermoplastic polyurethane (TPU) matrix. A twin-screw extruder (TSE) equipped with a simple CO2 injection unit consisting of a standard Gas Cylinder, regulator, valve, and metal hose is employed for the melt mixing. Results from the structural, thermal, rheological, mechanical, microcellular injection molding, dielectric, and thermal conductive properties of the SGAP pellets, in addition to the resultant TPU/NGP nanocomposites, confirmed significantly improved dispersion compared to those obtained via conventional melt blending in the TSE. This technique offers a simple, cost-effective approach to the large-scale production of high-performance polymer nanocomposites without the requirement for complicated processing steps such as supercritical fluid (SCF) processes or chemical treatments.
A Amirzadeh - One of the best experts on this subject based on the ideXlab platform.
-
producing molten metal droplets smaller than the nozzle diameter using a pneumatic drop on demand generator
Experimental Thermal and Fluid Science, 2013Co-Authors: Mehdi Raessi, A Amirzadeh, Sanjeev ChandraAbstract:Abstract A pneumatic droplet generator to produce molten metal droplets smaller than the nozzle diameter is described. The generator consists of a heated Cylinder in which a cavity is machined. A nozzle is fit into a stainless steel nozzle holder and attached to the bottom plate of the generator. The system is connected to a Gas Cylinder through a solenoid valve. Opening the valve for a preset time creates a pulse of alternating negative and positive pressure in the Gas above the surface of the molten metal, and a droplet is ejected through the nozzle. The effect of various parameters such as the ejection frequency, nozzle diameter, pulse width and secondary Gas flow on droplet formation is investigated. This method made it possible to produce droplets as small as 60% the nozzle diameter. An approximate analytical method is studied to understand the liquid behavior within the nozzle, estimate the droplet size, and investigate the effect of the secondary Gas flow pressure on droplet diameter.
