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Conference Proceedings
EVALUATION OF GATE GEOMETRY AND PROCESSING VARIABLES EFFECTS ON GATE FREEZING TIME BY CFD METHOD
The aim of the present work was to study the effects of gate geometry and processing parameter on the gate freezing time and quality of the injection molding by using CFD method. The simulation was performed on two different gate geometries, Pin and Fan gate for polyacetal.The gate freezing time was predicted on the basis of solidified fraction as a function of time. In the experimental works the gate freezing time was taken as the time which the weight of moldings remained unchanged. From the predicted results, it was found that at equal gate cross-section, the freezing time of fan gate was shorter than that of the Pin gate. A good agreement was found between the predicted and experimental results.
NON-ISOTHERMAL FILM BLOWING PROCESS STABILITY ANALYSIS BY USING VARIATIONAL PRINCIPLES
In this work, film blowing stability analysis has been performed theoretically by using minimum energy approach for non-Newtonian polymer melts considering non-isothermal processing conditions with the aim to understand the complicated link between processing conditions, machinery design and material properties.Specific attention has been paid to the investigation of the complicated links between polymer melt rheology (shear thinning, flow activation energy, Newtonian viscosity, melt strength), processing conditions (heat transfer coefficient, mass flow rate, die exit temperature, cooling air temperature) and film blowing stability. It has been found that the theoretical conclusions are in very good agreement with the experimental reality supporting the validity of the used numerical approach and film blowing model.
PHYSICAL AND MECHANICAL PROPERTIES OF HIGH MOLECULAR WEIGHT POLYSTYRENE NANOPARTICLES
The high molecular weight (MW) polystyrene (PS) particles were synthesized by benzoyl peroxide, sodium lauryl sulfate and styrene. The particle size varies from micro to nanometer. The microscopy analysis (TEM/AFM) shows the spherical shape of PS particles. The effects of particle size, which varies from micro to nanometer scale glass transition temperature (Tg), and mechanical properties were studied. DSC show that the nanoparticles of PS have higher Tg compared to the microsized PS. The elastic modulus of individual nanospherical PS particles is computed from ƒ??force-distanceƒ?? mapping curves of AFM.
THE MANUFACTURE OF CARBON NANOTUBE COMPOSITE MATERIALS USING SUPERCRITICAL CARBON DIOXIDE
In order to obtain the unique mechanical, electrical, and thermal properties potentially provided by carbon nanotubes (CNTs) in thermoplastics, it is necessary to reach a well-dispersed level of CNTs. Using a technique in which the CNTs are exposed to supercritical CO2 (scCO2) and then expanded by rapid pressure release, it is revealed by means of SEM that the CNTs exposed to scCO2 at certain temperatures, pressures and exposure time have a more dispersed but aligned structure in a thermoplastic. The stiffness and CNT dispersion of CNTs/RADEL (polyphenylsulfone) composites prepared with the use of scCO2 are significantly improved relative to those prepared by means of direct melt blending.
GAS CHANNEL DESIGN FOR GAS ASSISTED MICRO INJECTION MOLDING
In previous work, gas assist micro injection molding produced significant improvements in the replication of microscale features and elimination of sink marks, but the gas channels were located beneath the features. Thus, the design, location, and size of the gas channels were investigated in this work. Filling simulations were used to evaluate a range of channel designs. For the most promising design, mold inserts were machined and used to injection mold polymethylmethacrylate parts containing microscale features. Molding trials showed that the 3.2-mm diameter channels could be located adjacent to the region with the microscale features and still enhance replication of the features.
INFLUENCE OF INJECTION MOLDING PARAMETERS ON THE ELECTRICAL RESISTIVITY OF POLYCARBONATE FILLED WITH MULTI-WALLED CARBON NANOTUBES
Polycarbonate (PC) composites with 2 wt% multiwalled carbon nanotubes (MWNT) were injection molded using an experimental design to evaluate the influences of holding pressure, injection velocity, mold temperature, and melt temperature on the electrical resistivity. For both composites variations in resistivity of the molded plates up to six orders of magnitude were found. The highest impact was determined for the injection velocity and the melt temperature. Transmission electron microscopy (TEM) images showed a skin layer with highly oriented nanotubes in case of high injection velocity.
SHRINK FORCE MEASUREMENT OF LOW SHRINK FORCE FILMS
Blends of linear low density polyethylene (LLDPE) and high pressure low density polyethylene (LDPE) are often used to produce films with different shrink forces.The differences in these shrink forces can be observed in practical shrink film applications although it has been difficult to quantify these differences in laboratory equipment. In this work we explore the measurement of shrink forces of low shrink force films by various laboratory methods with examples given of the shrink forces measured on LLDPE/LDPE blends which had proven difficult to measure by other existing techniques.
EFFECT OF TRIACETYL CELLULOSE FILM SURFACE HYDRATION ON THE ADHESION STRENGTH TO POLYVINYL ALCOHOL (PVA) FILM
Triacetyl cellulose (TAC) film has been used as a protective film for the polyvinyl alcohol (PVA) based polarization film in liquid crystal display (LCD). Adhesion strength between TAC and PVA films by PVA type adhesive must be maintained sufficiently to keep the dimensional stability of polarized PVA film under severe environmental conditions, such as high temperatures and high humidity. In this study, the surface hydration of TAC film and adhesion process between TAC and PVA films were investigated. The surface hydration of TAC enhanced the adhesion strength between TAC and PVA films. Consequently, this provides better dimensional stability of polarized PVA film protected by TAC film. In addition to adhesion strength, appropriate draw ratio and the crosslinking in PVA film were also required for better dimensional stability in polarized PVA film.
LONG GLASS FIBER ORIENTATION IN THERMOPLASTIC COMPOSITES USING A MODEL THAT ACCOUNTS FOR THE FLEXIBILITY OF THE FIBERS
Mechanical properties of long glass fiber composites
used in various industrial applications are dependant
upon the fiber orientation within the part. To date
however simulations with the ability to predict fiber
orientation as a function of mold design are not available.
In this study several options are explored to predict the
orientation of long glass fibers in the concentrated regime
that take the flexible nature of these fibers into account.
Flow through a center gated disk geometry is simulated
numerically for high concentrations of long glass fiber in
a polypropylene (PP) matrix. For this a flow uncoupled
2D finite element (FEM) analysis was performed using a
discontinuous Galerkin method for the orientation
equations. Numerical results based on the uncoupled
simulations are compared with experiment for
verification.
LONG GLASS FIBER ORIENTATION IN THERMOPLASTIC COMPOSITES USING A MODEL THAT ACCOUNTS FOR THE FLEXIBILITY OF THE FIBERS
Mechanical properties of long glass fiber composites, used in various industrial applications, are dependant upon the fiber orientation within the part. To date, however, simulations with the ability to predict fiber orientation as a function of mold design are not available. In this study, several options are explored to predict the orientation of long glass fibers in the concentrated regime that take the flexible nature of these fibers into account. Flow through a center gated disk geometry is simulated numerically for high concentrations of long glass fiber in a polypropylene (PP) matrix. For this, a flow uncoupled 2D finite element (FEM) analysis was performed using a discontinuous Galerkin method for the orientation equations. Numerical results, based on the uncoupled simulations, are compared with experiment for verification.
DEVELOPMENT OF GRUBBSƒ?? CATALYZED COMPOSITIONS AS A SINGLE ƒ??COMPONENT AMBIENT CURABLE BINDER
One-component ambient curable liquid compositions have been formulated based on the Grubbsƒ?? catalyzed chemistry to produce in-situ concentrated particulate composites without laminar mixing. The modified Grubbsƒ?? catalyzed compositions containing monomeric reactive ingredients are of much lower viscosity in order to facilitate the infusion step into the packed bed of catalyst-coated particulates. Such formulations are free of complex liquid mixing and precise metering steps required for its twopart binder counterpart resulting in simple and neat net shape manufacturing.
EFFECT OF COPPER ALLOY MOLD TOOLING ON CYCLE TIME AND PRODUCT QUALITY
The performance of copper alloy mold tool materials in injection molding has been compared experimentally to that of tool steel with respect to cycle time, part quality and energy consumption using in-process monitoring techniques. A mold insert was manufactured from tool steel and in an identical geometry from 4 berylium-free copper alloys, with copper content ranging from 85 - 96%.Results showed that copper alloy mold tools exhibited cooling rates up to 29% faster than conventional tool steel and that cooling rate was directly related to copper content of the alloy. Experimental results were compared to those using a commercial simulation package with boundary conditions at the mold surface being modified according to mold tooling material.
LIQUID SENSING PROPERTIES OF FIBERS PREPARED BY MELT SPINNING
FROM POLY (LACTIC ACID) CONTAINING MULTIWALLED CARBON
NANOTUBES
Poly (lactic acid) (PLA)/multiwalled carbon nanotube (MWNT) fibers melt spun with different take-up velocities were investigated with respect to their liquid sensing properties. Transmission electron microscopy (TEM) and
RAMAN spectroscopy indicated enhanced MWNT
orientation along the fiber axis when processed with
increased take-up velocity. The composite materials were
produced using twin screw extrusion with MWNT
contents ranging from 0.5 to 5.0 wt%. The electrical
resistance change of the fibers caused by contact with
different solvents was recorded for immersion/drying
cycles. The fibers sensitivity towards resistance change
during solvent contact decreased with higher MWNT
orientation in the fibers due to increased take-up velocity
and increasing MWNT content.
LIQUID SENSING PROPERTIES OF FIBERS PREPARED BY MELT SPINNING FROM POLY (LACTIC ACID) CONTAINING MULTIWALLED CARBON NANOTUBES
Poly (lactic acid) (PLA)/multiwalled carbon nanotube (MWNT) fibers melt spun with different take-up velocities were investigated with respect to their liquid sensing properties. Transmission electron microscopy (TEM) and RAMAN spectroscopy indicated enhanced MWNT orientation along the fiber axis when processed with increased take-up velocity. The composite materials were produced using twin screw extrusion with MWNT contents ranging from 0.5 to 5.0 wt%. The electrical resistance change of the fibers caused by contact with different solvents was recorded for immersion/drying cycles. The fibers sensitivity towards resistance change during solvent contact decreased with higher MWNT orientation in the fibers due to increased take-up velocity and increasing MWNT content.
STRUCTURE-PROPERTY-PROCESSING RELATIONSHIPS OF OBC/SEBS BLENDS
The structure-property-processing relationships of partially hydrogenated styrene/ethylene-butylene/styrene block copolymer (SEBS) / olefin block copolymer (OBC) blends were studied. Morphological results revealed that the OBC formed an immiscible blend with SEBS. In SEBS rich compositions adding OBC had minimal impact on physical properties such as tensile behavior.However the addition of an OBC greatly lowered melt viscosity improving processability and high temperature compression set. In OBC rich blends the addition of SEBS imparted stronger strain hardening to OBC.
EFFECTS OF HYDROLYSIS AGEING ON THE PERFORMANCE AND DIMENSIONAL STABILITY OF GLASS-FIBER REINFORCED POLYAMIDE 66
Results of an in-depth study of hydrolysis testing on the mechanical performance, weight change, and dimensional stability of injection moulded glass-fiber reinforced polyamide 66 automotive composites are presented. Composite and resin samples have been characterised after conditioning in water-glycol mixtures at 70?øC, 120?øC and 150?øC for a range of times up to 1000 hours. The results reveal that hydrothermal ageing results in significant changes in the mechanical performance, weight, and dimensions of these materials. Mechanical performance after conditioning at different temperatures could be superimposed when considered as a function of the level of fluid absorbed by the composite matrix.
STRUCTURE MECHANICAL AND THERMAL PROPERTIES OF POLY (3-HYDROXYBUTYRATE-CO-HYDROXYVALERATE) (PHBV)/Zn-Al STEARATE LAYERED DOUBLE HYDROXIDE (LDH) NANOCOMPOSITES
Poly (3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) /Layered Double Hydroxide (LDH) nanocomposites were prepared by solution intercalation. The structure thermophysical and mechanical properties were studied by means of X-ray diffraction scanning electron microscopy differential scanning calorimetry thermogravimetry analysis dynamic mechanical analysis and mechanical testing. Experimental data showed that intercalated nanocomposites were obtained the melting temperature and enthalpy of melting were decreased and the mechanical and thermomechanical properties were improved. (Ref.6)
CARBON FIBER, NANOFIBER AND NANOSPRING-BASED LLDPE COMPOSITES: EFFECT OF PROCESSING CONDITIONS ON ELECTRICAL AND MECHANICAL PROPERTIES.
The effect of processing on electrical and mechanical properties of linear low density polyethylene composites reinforced by mesophase pitch-based carbon fibers, carbon nanofibers and helically coiled carbon nanotubes was studied. Batch mixing and twin-screw extrusion was used for melt-mixing the matrix and the filler. Optical microscopy and scanning electron microscopy were used for assessing the morphology. In general, the electrostatic dissipation, electrical conductivity, modulus and yield stress increase with increasing filler content; however, tensile strength and elongation-at-break decrease. The type of filler and its dispersion affected the final properties.
ZINC ALUMINUM LAYER DOUBLE HYDROXIDE IBUPROFEN PLLA NANOCOMPOSITES: SYNTHESIS STRUCTURE AND CHARACTERIZATION
The purpose of this research was to study the intercalation of the anions of Ibuprofen non-steroidal antiinflammatory drugs (NSAIDs) -methyl-4-(2- methylpropyl)-benzene acetic acid into a layer double hydroxide (Zn-Al LDH) to form a new organic-inorganic hybrid intercalated material and the formation of nanocomposite with Poly (l-Lactic acid) (PLLA). The synthesis was achieved through two steps. The first step is the modification of layer double hydroxide with Ibuprofen anions. The second is the dispersion of the LDH into PLLA. The resulting organo-inorganic hybrid material was characterized by X-ray Diffraction (XRD) Differential Scanning Calorimetry (DSC) and Tensile Test. X-ray diffraction evinces the presence of dispersion of LDH and intercalation.
DESIGN AND SIMULATION OF INJECTION MOLD FOR MOUSE SHELL BASED ON PRO/ENGINEER AND MOLDFLOW
The 3D models of gating system, ejection
mechanisms and cooling system of the mouse shell for
injection mold are designed by using Pro/ENGINEER
software. MOLDFLOW software is utilized for CAE
analysis. Three schemes are obtained by changing the
injection molding process conditions, improving the gate
location and cooling system. After comparing the volume
shrinkage during injection, shrink marks index, filling
time, all the factors leading to the total deformation of the
products and the clamping force, the best scheme is
obtained. The results showed that simulation analysis
method can not only improve the successful probability of
mold trial, but also shorten the production development
cycle of developing product.
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