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Conference Proceedings
SIMULATION AND ANALYSIS OF FIBER ORIENTATION IN INJECTION MOLDED BIPOLAR PLATES FOR FUEL CELL
Yin-Jiun Lin , Sheng-Jye Hwang , Huei-Huang Lee , Durn-Yuan Huang, May 2010
This research took bipolar plate of Proton Exchange Membrane Fuel Cell (or PEMFC) as the study case, and used Moldex3D mold flow analysis software to analyze the flow of fiber material. The bipolar plate was fabricated through injection molding process, and observed the fiber orientation with Scanning Electron Microscopy (or SEM). This research used PA6 (Polyamide, Nylon6) and +40% carbon fiber. Fiber (Length 200?¬m / Diameter 10?¬m). Taguchi methods was utilized to analyze the experiment. It adopted fillet (round corner) design on the channel, and the finished product had a size of 100mmX100mmX3.6mm, and the channel was 1.2mm in its width and depth. Different injection process conditions were used: channel configuration direction (parallel and vertical to filling direction respectively), melt temperature, mold temperature, injection pressure, hold pressure, back pressure, injection rate and screw speed. Experimental factors were applied to mold test pieces and measured. The results of this research showed that the fiber would turn around and entangle together, and thus decreased the electrical resistance when the channel was vertical to the filling direction. The uniformity of resistance would be increased when the channel was parallel to the filling direction.
NEW INSIGHTS IN PVT-BEHAVIOR FOR HIGH PRECISION IN INJECTION MOLDING
N. Rudolph, G. W. Ehrenstein, T. A. Osswald1, May 2010
The main impact factors on shrinkage and dimensional stability are the temperature and pressure the melt is subjected to during processing. Hence, pvT-behavior can be used to predict the dimensional deviations of plastic parts. Since large differences exist between predicted and actual shrinkage, a closer look was taken at the effect of pressure and pressurization on the dimensions of the part. For this study, fundamental examinations of the behavior of amorphous thermoplastics during compression and cooling were made. These include the analysis in the different phases as well as the variation of the pressuretemperature- cycles and their succession. It was found that the specific volume and therefore the thermal expansion coefficient and compressibility are dependent on the pathway of the process. In this paper, the results of these experiments are shown and the impact on the shrinkage behavior during injection molding is discussed. In the outlook the application of these insights in a new injection molding technology ƒ?? the Compression Induced Solidification (CIS) - is presented.
INVESTIGATION OF MOLD HEATING BY INDUCTION HEATING WITH EMBEDDED COILS WITHIN MOLD INTERIOR
Shia-Chung Chen, Yu-Tseng Lin, Jen-An Chang, May 2010
The effects of coil to cavity surface distance on the heating efficiency of induction heating using embedded coils within the mold base is investigated. Simulation was also performed by integration of both thermal and electromagnetic analysis modules using ANSYS. For a 15 mm coil to cavity surface distance it takes 20 seconds for mold temperature to rise from 80?øC to 110?øC (1.75?øC /s heating rate), whereas for the 20 mm distance case mold temperature rise from 80?øC to 85?øC in 20 seconds (heating rate 0.25?øC/s). Simulation also shows good agreement with experiments.
MOLD SURFACE HEATING USING HIGH FREQUENCY INDUCED ELECTROMAGNETIC PROXIMITY EFFECT
E.H. Qua, P.R. Hornsby, G.M. McNally, S. Sharma, G. Lyons, D. McCall, May 2010
High frequency induced electromagnetic proximity effect is used to achieve mold surface heating. A pair of flat mold plates (100 mm by 100 mm by 32 mm) was used for the experiments. When a high frequency current flows successively into the two mold plates, an electromagnetic proximity effect is induced between the mold plates and heats the mold surface. Simulation via ANSYS was developed by integration of both thermal and electromagnetic analysis modules. It takes 10s to heat the mold surface from 40oC to 80oC with a heating speed of about 3.68oC/s, and the simulation also shows good agreement with experiments.
PREPARATION AND CHARACTERISATION OF POLYVINYL ALCOHOL NANOCOMPOSITES MADE FROM CELLULOSE NANOFIBRES
E.H Qua , P.R Hornsby , G.M. McNally , S. Sharma , G. Lyons , D. McCall, May 2010
A method had been developed using a combination of acid hydrolysis and ultrasound to obtain a high yield of cellulose nanofibres from flax fibres and microcrystalline cellulose (MCC). Polyvinyl alcohol (PVA) nanocomposites were prepared using these additives by a solution casting technique. The cellulose nanofibres and nanocomposites films produced were characterised using FTIR XRD TGA SEM and TEM. A significant enhancement in thermal and mechanical properties was achieved with low addition of cellulose nanofibres to the polymer matrix.
A DIRECT 3D NUMERICAL SIMULATION CODE FOR EXTRUSION AND MIXING PROCESSES
Chantal David , Rudy Valette , Thierry Coupez , Bruno Vergnes, May 2010
This work focuses on the development of ageneral finite element code called Ximex?? devoted to thethree-dimensional direct simulation of mixing processes of complex fluids. The code is based on a simplified fictitious domain method coupled with a ƒ??level-setƒ? approach to represent the rigid moving boundaries such as screws and rotors as well as free surfaces. These techniques combined with the use of parallel computing allow computing the time-dependent flow of generalized Newtonian fluids in large and complex processes involving moving free surfaces which are treated by a level-set/Hamilton-Jacobi method. Two flow case studies will be presented in this paper: the flow within a twinscrew extruder and the flow in a batch mixer.
BLENDS OF INFUSE' OLEFIN BLOCK COPOLYMERS FOR ADHESION TO POLAR SUBSTRATES
Ashish Batra , Laura Weaver , Lisa Madenjian , Hamed Lakrout , Jose M. Rego, May 2010
INFUSE' Olefin Block Copolymers (OBCs) are polyolefins with blocks of hard (highly rigid) and soft (highly elastomeric) segments. These materials break the traditional relationship of flexibility and heat resistance, while offering significantly improved compression set and faster cycle times in injection molding applications.However, adhesion of these polyolefin based materials to polar substrates remains expectedly poor, but blending with other polymers can improve adhesion performance. In this paper the structure-property relationships of Olefin Block Copolymer (OBC)-based blends that offer adhesion to polar substrates will be discussed.
EFFECT OF POLYMER FILM PERMEABILITY ON RETARDING OR PREVENTING CORROSION AND MOLD
Donna L. Visioli , John C. Chen , Bruce E. Urtz , Shi Hua Zhang, May 2010
Damage of products resulting from mold and rust contribute to millions of dollars of losses in a variety of industries. Rust and mold are affected by moisture in the surrounding environment; therefore it is critically important to control moisture vapor in order to prevent formation of rust and mold. Recently ionomers having novel performance (increased selective gas transmission while maintaining mechanical properties) have been developed. In this paper we demonstrate efficacy of these ionomers in preventing rusting and mold growth and discuss their use in film structures which have both good mechanical properties as well as appropriate gas transmission properties.
EFFECT OF POLYMER FILM PERMEABILITY ON RETARDING OR PREVENTING CORROSION AND MOLD
Donna L. Visioli , John C. Chen , Bruce E. Urtz , Shi Hua Zhang, May 2010
Damage of products resulting from mold and rust contribute to millions of dollars of losses in a variety of industries. Rust and mold are affected by moisture in the surrounding environment; therefore, it is critically important to control moisture vapor in order to prevent formation of rust and mold. Recently, ionomers having novel performance (increased selective gas transmission while maintaining mechanical properties) have been developed. In this paper, we demonstrate efficacy of these ionomers in preventing rusting and mold growth and discuss their use in film structures which have both good mechanical properties as well as appropriate gas transmission properties.
ACADEMIC POLYMER EDUCATION AS UNDERGRADUATE AND GRADUATE DEGREE IN IRAN AND THE WORLD
Ali Abbasian, Pegah M. Hosseinpour, May 2010
As a standalone program, polymer education started about 20 years ago in Iran, founded based on the experiences of a few academics who had accomplished their graduate education mostly in European universities. Now it seems that a re-evaluation of this program is required in comparison with other countriesƒ?? experiences in polymer education (e.g. a standalone polymer education program started 60 years ago in USA). Here, the situation of academic polymer education in Iran and ten other universities worldwide has been studied. The roots of polymer engineering as a Major program in Material or Chemical Engineering, as well as other issues such as the offering department, curriculum and cooperation with industry have been discussed and compared, in order to improve the polymer education situation.
SIMULATING THE FLOW LENGTH TO THICKNESS RATIO IN ULTRA HIGH-SPEED INJECTION MOLDING BY MOLDEX3D ANALYSIS
Rodrigo Orozco, Ivan Lopez, Robert Rowlands, Tim Osswald, May 2010
In thin-wall injection molding, due to the very fast polymer melt heat transfer to the mold wall, the melt solidifies quickly during the filling stage. In this study, ultra high-speed injection molding (up to 600mm/s injection speed) was conducted. A mold of spiral shape, 0.4mm thick, is used to measure the flow length under different filling speeds. Simulation by Moldex3D was also performed for verification. For injection speeds of 100 mm/s, 500 mm/s, 1000 mm/s and 1400mm/s, the corresponding experimental results for the flow length to thickness ratios are 335, 467.5, 605 and 640, respectively. The simulation results also show that different heat transfer coefficients affect the flow length through variable injection speeds. Slower injection speeds require a higher heat transfer coefficient, whereas higher injection speeds only require a lower heat transfer coefficient.
STRESS ANALYSIS OF 2-D AND 3-D PIN-JOINED COMPOSITE LAMINATE PLATES USING RADIAL BASIS FUNCTIONS METHOD
Rodrigo Orozco , Ivan Lopez , Robert Rowlands , Tim Osswald, May 2010
Some difficulties that arise in the analysis of bolted or riveted connections in polymer composite structures are the failure modes and their interactions which depend on the strengths in the principal material directions. This paper describes the meshless Radial Basis Functions Method (RFM) utilized to simulate the homogeneous linear elastic mechanical behavior of special 2-D and 3-D polymer composite structures with isotropic and orthotropic properties under unidirectional loads and compares the stress state with analytical infinite-plate solutions and Finite Element Method (FEM) models. Different plate sizes with various boundary conditions are simulated and discussed.
STRESS ANALYSIS OF 2-D AND 3-D PIN-JOINED COMPOSITE LAMINATE PLATES USING RADIAL BASIS FUNCTIONS METHOD
Rodrigo Orozco , Ivan Lopez , Robert Rowlands , Tim Osswald, May 2010
Some difficulties that arise in the analysis of bolted or riveted connections in polymer composite structures are the failure modes and their interactions, which depend on the strengths in the principal material directions. This paper describes the meshless Radial Basis Functions Method (RFM) utilized to simulate the homogeneous linear elastic mechanical behavior of special 2-D and 3-D polymer composite structures with isotropic and orthotropic properties under unidirectional loads and compares the stress state with analytical infinite-plate solutions, and Finite Element Method (FEM) models.Different plate sizes with various boundary conditions are simulated and discussed.
MEASURING THE INFLUENCE OF UV STABILIZERS (HALS) ON MELT FRACTURE IN POLYETHYLENE PACKAGING FILMS BY OPTICAL PROFILOMETRY
T. Tikuisis, J. Bayley, D. Wunderlich, M. Adams, May 2010
Modern flexible packaging requires excellent aesthetic properties for film and print appearance (e.g. high gloss). These, and other optical properties, are directly influenced by film surface roughness, of which melt fracture is a leading cause. Such film surface irregularities can also negatively impact printing quality by causing distortion. In this paper, film surface roughness effects influenced by UV stabilizers are investigated. The use of optical profilometry to quantify differences in melt fracture performance will also be discussed.
NANOPARTICLE INDUCED RADIAL STRUCTURAL GRADIENT IN MELT-SPUN POLYPROPYLENE/PPGMA FIBERS
Jane Hitomi Fujiyama-Novak, Miko Cakmak, May 2010
The role of nanoparticles on the evolution of structural hierarchy in clay and polymer for fibers was elucidated. The stream of polypropylene nanocomposite that exited the die without application of a take up presented orientation gradient in the radial direction with the broad surfaces of the clay parallel to the surface of the fibers. The polymer exhibited high preferential orientation levels in the edge of the fiber. With take up, the clay particles enhanced the orientation of amorphous and crystalline phases. Measurements of the clay orientation revealed that the nanoplatelets contributed positively to the birefringence of the fibers.
NANOCOMPOSITE POLYPROPYLENE FILM FOR FOOD PACKAGING APPLICATIONS
Sarah Schirmer , JoAnn Ratto , Danielle Froio , Christopher Thellen , Jeanne Lucciarini, May 2010
Polypropylene (PP) was compounded with 7.5% montmorillonite layered silicate (MLS) and 2.5% compatibilizer; then extruded to produce both blown and cast nanocomposite films. The nanocomposite films were characterized and morphology specifically from x-ray diffraction (XRD) and transmission electron microscopy (TEM) showed limited interaction between the PP and MLS. There was however significant improvement in thermal barrier and mechanical properties over the neat PP films both before and after exposure to a high temperature sterilization process.
RELATIONSHIP BETWEEN SHEAR STRAIN AND MICROSTRUCTURE OF POLYPROPYLENE NANOCOMPOSITE BASED ON RHEOLOGICAL ANALYSIS
Guo Jiang , Han-Xiong Huang, May 2010
Polypropylene/clay nanocomposite was compounded by a twin-screw extruder. Rheological property development of samples collected from four different positions along the extruder and microstructure of the endobtained samples was investigated. Flow field parameters including shear rate and residence time profiles were simulated. Then the shear strain was calculated. The relationship between the shear strain and microstructure of nanocomposite was analyzed based on rheological analysis. Results showed that dispersion of clay in polymer matrix can be reflected by the shear strain generated by the flow along the extruder.
EFFECT OF PROCESSING PARAMETERS ON PULSE COOLING EFFICIENCY IN INJECTION MOLDING
Ashish Batra, Lisa Madenjian, Wenbin Liang, Gary Marchand, , Dan Moldovan, Jacob Jones, May 2010
Pulse cooling provides a convenient way for varying mold temperature within limited range. Even so, it can reduce cycle time or improve part qualities. Due to its narrow operation window, choosing proper parameters is rather important. In this study, influences of flow temperature (FT), stop temperature (ST) and temperature sensor locations for coolant switch on the cooling efficiency are investigated. The results show that mold temperature varies from 66.5ƒøC to 71.5ƒøC when ST increases from 700C to 760C. When sensor location changes from 4 mm to 8mm beneath mold surface, mold surface temperature will increase from 670C to 68.50C.
STRUCTURAL STUDIES ON POLYPROPYLENE NANOCOMPOSITES DURING COMPLETE UNIAXIAL FILM PROCESSING CYCLE
Jane Hitomi Fujiyama-Novak, Miko Cakmak, May 2010
The mechanistic changes that take place during heating-stretching-holding-cooling of typical film processing of polypropylene nanocomposite were investigated using a hybrid real-time spectral birefringence technique. The results on as-cast films indicated the nanoplatelet poles were highly oriented perpendicular to the plane of the film resulting in a uniplanar axial symmetry. During the heating, real-time measurements revealed that the presence of clay particles reduced the rate of PP/PPgMA melting. Throughout the deformation, the nanoclay enhanced the molecular orientation/strain-induced crystallization as compared to the PP. The nanocomposite films were found to exhibit a more affine deformation and increased the toughness of the system.
PLA PROPERTY IMPROVEMENT: IMPROVING THE PRACTICAL HEAT RESISTANCE OF POLYLACTIC ACID (PLA)
Shixiong Zhu , Roger Avakian, May 2010
Polylactic Acid (PLA) is a renewable polymer with many unique features including compostability. However PLA suffers from several performance deficiencies which limit its market potential. A key deficiency is its ability to withstand elevated use temperatures above 55C. PolyOne’s objective was to explore a range of approaches to identify a practical path to improved heat performance while seeking to maximize renewable content and processability. This paper addresses the industry need for a high renewable content polymer with practical heat resistance without relying on any additional thermal treatments such as annealing. Various PLA-based compounds were prepared and screened using DMA in an effort to correlate results to the heat distortion temperature (HDT) exhibited by injection molded PLA. It was concluded that polymer blends offered the greatest commercial viability of all the approaches considered under normal injection molding conditions. Multi-phase compatible polymer blends were found to have the most significant impact on blend properties. All components of the preferred blend composition are commercially available today. Heat performance can be tailored based upon performance requirements and bio-content objectives. The PLA content of the blends studied varied from 72% to 35% while the corresponding HDT (under 0.455 MPa load) ranges from 57 ºC to 101 ºC. Potential increased bio-derived contents are also considered.


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