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Conference Proceedings

TRUE 3D NUMERICAL SIMULATION IN INJECTION COMPRESSION MOLDING (ICM)
H. Inoya, W. Klinklai, Y. W. Leong, H. Hamada, May 2010

Generally, injection compression molding (ICM) can provide better product quality than that of conventional injection molding (CIM) in some injection processes and products, such as micro-injection molding, less residual stress parts, and so on. To get a better understanding of ICM, a 3D simulation technology based on finite volume method is proposed. In this study, the influence of various process parameters with ICM is performed by using light guide plate (LGP) models. The cavity pressure distribution with ICM is lower and more uniform than that with CIM which will have more opportunities result in lower volume shrinkage and get better product quality.

MECHANICAL PROPERTIES OF RECYCLED PET/PP INJECTION MOLDINGS
H. Inoya , W. Klinklai , Y. W. Leong , H. Hamada, May 2010

Compatibilization effects on the phase morphology and mechanical properties of post-consumer recycled poly(ethylene terephathalate) (RPET)/ polypropylene (PP) blends were investigated. The blending of RPET and PP (RPET/PP:95/5) was carried out by a singlescrew extrusion process in the presence of various amounts of compatibilizer ranging from 0-35 phr based on the PP content. The compounded materials were injection molded into dumbbell test pieces which were subsequently used for mechanical and morphological characterizations. The addition of compatibilizer of up to 15 phr resulted in a size reduction of the dispersed phase while an apparent increase in density of the blends suggests an improvement in interfacial interaction following the depletion of hollow ligaments between the PP and RPET phases. The changes in morphological structure significantly affect the tensile and impact resistance of the moldings. An elongation at break (EB) of more than 350% could be achieved with the incorporation of just 15 phr of compatibilizer (as compared to <90% EB for un-compatibilized specimens) while significantly better impact performance was observed in all compatibilized specimens.

MICRO-FEATURE REPLICATION OF CYCLIC OLEFIN COPOLYMER AT ELEVATED MOLD TEMPERATURE
Peiman Mosaddegh , David C. Angstadt, May 2010

The focus of this study is on the ability of Cyclic Olefin Copolymer (COC) to replicate micron and sub-micron features when molded at an elevated mold temperature without externally applied pressure. Molding was performed on a treated silicon mold containing surface features as small as 700nm in depth with aspect ratios ranging from 5 to 0.02. In this study temperature was selected in order to overcome the viscosity resistance of polymer based on contact angle (wettability) measurements. Since increasing mold temperature can cause sticking to the mold surface an anti-adhesive layer made by TCS has deposited on the surface to facilitate mold release. Feature replication was assessed using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) to compare the molded feature depth ratio and surface roughness. It was observed that for the features with an aspect ratio (depth/width) bigger than 0.8 the quality of the feature replication declines. Without the anti-adhesive layer COC has shown rough surface finish especially in low aspect ratio features because of sticking to the silicon oxide layer. Using anti-adhesive improved surface finish of molded part and reduced the defects such as flashing and tear-off during demolding.

MICRO-FEATURE REPLICATION OF CYCLIC OLEFIN COPOLYMER AT ELEVATED MOLD TEMPERATURE
Peiman Mosaddegh , David C. Angstadt, May 2010

The focus of this study is on the ability of Cyclic Olefin Copolymer (COC) to replicate micron and sub-micron features when molded at an elevated mold temperature without externally applied pressure. Molding was performed on a treated silicon mold containing surface features as small as 700nm in depth with aspect ratios ranging from 5 to 0.02. In this study, temperature was selected in order to overcome the viscosity resistance of polymer based on contact angle (wettability) measurements. Since increasing mold temperature can cause sticking to the mold surface, an anti-adhesive layer made by TCS has deposited on the surface to facilitate mold release. Feature replication was assessed using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) to compare the molded feature depth ratio and surface roughness. It was observed that for the features with an aspect ratio (depth/width) bigger than 0.8 the quality of the feature replication declines. Without the anti-adhesive layer, COC has shown rough surface finish especially in low aspect ratio features because of sticking to the silicon oxide layer. Using anti-adhesive improved surface finish of molded part and reduced the defects such as flashing and tear-off during demolding.

NANOLAYERING AS AN ENABLING TECHNOLOGY FOR STUDYING FRACTIONATED CRYSTALLIZATION OF POLYPROPYLENE
D.S. Langhe , A. Hiltner , E. Baer, May 2010

Layer-multiplying coextrusion was used to fabricate assemblies of 257 layers in which PP nanolayers alternated with thicker polystyrene (PS) layers. When the assembly was heated into the melt interfacial driven breakup of the 12 nm PP layers produced a dispersion of submicron PP particles in a PS matrix. In the absence of a nucleating agent the submicron particles obtained from breakup of 12 nm PP layers crystallize almost exclusively by homogeneous nucleation at about 40 ºC. Addition of a nucleating agent to the PP layers offers a unique opportunity to study the nature of heterogeneous nucleation.

NANOLAYERING AS AN ENABLING TECHNOLOGY FOR STUDYING FRACTIONATED CRYSTALLIZATION OF POLYPROPYLENE
D.S. Langhe , A. Hiltner , E. Baer, May 2010

Layer-multiplying coextrusion was used to fabricate assemblies of 257 layers, in which PP nanolayers alternated with thicker polystyrene (PS) layers. When the assembly was heated into the melt, interfacial driven breakup of the 12 nm PP layers produced a dispersion of submicron PP particles in a PS matrix. In the absence of a nucleating agent, the submicron particles obtained from breakup of 12 nm PP layers crystallize almost exclusively by homogeneous nucleation at about 40 ?§C. Addition of a nucleating agent to the PP layers offers a unique opportunity to study the nature of heterogeneous nucleation.

THREE-DIMENSIONAL MODELING OF GAS PENETRATIONS DURING GAS-ASSISTED INJECTION MOLDING
Reiichi Konishi, Kazushi Yamada, Yasuo Hashimoto, Yew Wei Leong, Tetsuya Tsujii, Hiroyuki Hamada, May 2010

Although Gas-Assisted Injection Molding (GAIM) has gained acceptance in eliminating sink marks and preventing warpage in the plastic industry, many problems are still encountered for the complicated gas-melt flow interactions. In this study, a full 3D numerical approach is proposed to model GAIM process. The behavior of gas penetration are investigated numerically. Simulation results are in the form of fully featured 3-D animations, giving highly realistic images of flow fields. The predicted melt front location and gas penetration behavior show good agreement with the experimental results, and several complex applications are shown as well.

MECHANICAL PROPERTIES OF HEAT-SEALED PART IN THERMAL LAMINATED FILM
Reiichi Konishi , Kazushi Yamada , Yasuo Hashimoto , Yew Wei Leong , Tetsuya Tsujii , Hiroyuki Hamada, May 2010

Plastic packaging has been a very important application that significantly improved our way of living. One of the most common forms of plastic packaging is the plastic bag which is often heat sealed at several ends. In order to increase the heat-seal performance of plastic bags laminated films e.g. oriented PP/cast PP have been used.However much solvent is used during the laminating process and the effects of volatile compounds on health and environment were the main concerns when introducing these solvents. Hence in this study a new lamination process i.e. thermal lamination was developed to avoid the usage of solvents. The characteristics of the thermal laminated films as well as their mechanical properties upon heat-sealing are discussed.

MECHANICAL PROPERTIES OF HEAT-SEALED PART IN THERMAL LAMINATED FILM
Reiichi Konishi , Kazushi Yamada , Yasuo Hashimoto , Yew Wei Leong , Tetsuya Tsujii , Hiroyuki Hamada, May 2010

Plastic packaging has been a very important application that significantly improved our way of living. One of the most common forms of plastic packaging is the plastic bag, which is often heat sealed at several ends. In order to increase the heat-seal performance of plastic bags, laminated films e.g. oriented PP/cast PP have been used. However, much solvent is used during the laminating process and the effects of volatile compounds on health and environment were the main concerns when introducing these solvents. Hence, in this study, a new lamination process, i.e. thermal lamination, was developed to avoid the usage of solvents. The characteristics of the thermal laminated films as well as their mechanical properties upon heat-sealing are discussed.

MECHANICAL PROPERTIES OF INJECTION-MOLDED JUTE/GLASS REINFORCED HYBRID COMPOSITES
Tomoko Ohta , Yoshihiro Takai , Yew Wei Leong , Asami Nakai , Hiroyuki Hamada , Tsutomu Nagaoka, May 2010

Bio-composites are generally made from natural fibers as reinforcement and a biodegradable polymer matrix such as poly(lactic acid) or poly(caprolactone).However the mechanical properties of these composites are relatively low. For practical applications glass fibers were added to create hybrid composites. The concept of ƒ??degree of greenƒ? is introduced to identify the true content of biodegradable material in the composite. Three different fiber hybridization methods are proposed i.e.dry blending mixing of pellets and sandwich injection molding. The mechanical properties of these hybrid composites are evaluated and the relation between the properties and degree of green is discussed.

DEVELOPMENT OF MOISTURE RESISTANT RECYCLED POLY(ETHYLENE TEREPHTHALATE)
Y. W. Leong , H. Inoya , S.F. Aminuddin , B.C. Ogazi-Onyemaechi , H. Hamada, May 2010

The recycling activities related to poly(ethylene terephthalate) PET has been slow since the material is always thought to possess inferior properties when compared to virgin PET. This study involves the development of novel processing methods to significantly enhance the properties of recycled PET (RPET) especially in terms of moisture resistance.This is particularly important especially when RPET is used for further processing that involves heating such as injection molding since the presence of moisture would severely degrade the material. The drying process of RPET pellets would also require at least a few hours which could significantly affect production cycles. The improvement in moisture resistance can be realized through the control of crystallinity and morphological structure of the RPET pellets during compounding and extrusion processes.

INVESTIGATION ON VARIOUS VARIOTHERM PROCESSES IN INJECTION MOLDING
Shoko Toyoyama, Tomohiko Sugie, Yuka Kobayashi, Asami Nakai, Hiroyuki Hamada, May 2010

In recent years, to eliminate defects and improve the product quality, many variotherm processes have been proposed and commercialized in injection molding. However, what the true function is for each technology and how the efficiency is from one technology to the other, are still not clear. In this study, we have systematically conducted various technologies, including Conventional Injection Molding (CIM), Rapid Heat Cycle Molding (RHCM), Induction Heating Molding (IHM), and Electricity Heating Mold (E-mold) by using 3D Transient Cool technology. The functions and the heating-cooling efficiency for each technology can be visualized. The comparison for all technologies is also performed.

DEGRADATION BEHAVIOR OF HEMP FIBER REINFORCED THERMOSETTING POLYMER
Shoko Toyoyama , Tomohiko Sugie , Yuka Kobayashi , Asami Nakai , Hiroyuki Hamada, May 2010

Natural fiber-reinforced composites are very attractive due to environmental considerations. There are currently many types of natural fibers that are suitable to be used as reinforcement in polymer composites. In this paper hemp fiber mat was selected to be the reinforcement for unsaturated polyester resin. In order to determine the long-term water resistance of this composite specimens were immersed into hot water.Weight changes of the specimens were recorded with time and their respective mechanical properties were determined through bending tests. A correlation was established between moisture absorption and mechanical performance of the composites.

STUDY OF POLY(1-BUTENE) SURFACE MODIFIED BY AIR PLASMA TREATMENT
N. O-Charoen, T. Hashimoto, Y. W. Leong, H. Hamada, May 2010

A low-temperature pulsed direct current discharge air plasma treatment has been used to improve the surface properties of poly(1-butene) films. The changes in the surface hydrophilicity and roughness of modified poly(1-butene) films were investigated by contact angle measurements, scanning electron microscopy and atomic force microscopy. These experiments revealed that the plasma treatment can greatly change the surface chemistry as well as morphology of poly(1-butene). The polar functional groups generated due to plasma treatment on the surface of poly(1-butene) sheets causes decrease in contact angle. However, the aging process of the plasma treated samples showed that the effect was not permanent. Scanning electron microscope and atomic force microscope observations revealed that the surface topography was changed by air plasma etching, and the surface roughness increases.

POLYMER MELT FLOW ANALYSIS IN SPIRAL FLOW INJECTION MOLDING
N. O-Charoen , T. Hashimoto , Y. W. Leong , H. Hamada, May 2010

The internal structure of polycarbonate / acrylonitrile-butadiene-styrene (PC/ABS) blend injection molding was investigated by using a spiral flow mold. The thickness of skin and core layers through thickness direction was evaluated from the size and shape of cavities (ABS rich region) in the cross sections of etched specimens.The microstructure development was analyzed from the computed solidification velocity of the polymer melt. As a result the maximum shear stress and solidification time of the resin was important in determining the final morphological properties.

POLYLACTIDE TOUGHENING USING IMPACT MODIFIERS
Siqiang Zhu , Rahul Rasal , Douglas Hirt, May 2010

The major objective of this research was poly(lactide) (PLA) toughening using two impact modifiers (IMs). IM1 was derived from biodegradable resource and IM2 was non-degradable ethylene-acrylate copolymer. Blend films were prepared using a single screw extruder, and their mechanical properties were measured using tensile testing. Results showed that the Young's modulus did not change significantly with increasing concentration of IM1, but decreased with IM2 concentration. The maximum elongation at break was 240% for IM1 at 8 wt% loading and 255% for IM2 at 12 wt% loading. Clarity of the films decreased with higher additive concentrations for both IMs, but IM1 gave clearer film than IM2 for given composition. AFM images showed IM1 dispersed in PLA as isolated islands at lower compositions and transitioned to short threads at higher compositions; IM2 existed mostly as islands. Annealing of the films at 100 ?§C for 1 h increased the percent crystallinity, but did not affect the mechanical properties significantly.

THE WARPAGE AND OPTICAL PROPERTY INFLUENCED BY THE PROCESS-INDUCED PROPERTY VARIATION IN MULTI-COMPONENT MOLDING
Nathalie Chapleau, Hongbo Li, Michel A. Huneault, May 2010

Sequential multi-component molding is one of great methods to fabricate the modern injection products. Previous literatures have shown that various parameters, including the product geometries and materials selection, will affect the warpage of final products significantly. However, the interaction between the first shot and the second shot is not clear. In this study, various process-induced properties of the first shot are taken into consideration for the further processing. Results, not only show that the process-induced properties can affect the warpage and optical property crucially but also further help discover the inside mechanism more comprehensively.

MELT EXTRUDED WATER-SOLUBLE STARCH-BASED FILMS
Nathalie Chapleau , Hongbo Li , Michel A. Huneault, May 2010

The interest for biodegradable and water-soluble packaging films has gained attention as they have a potential in several applications such as pouches for powders and liquids, liners and bags, and medical delivery devices. In this work, starch-based materials are used to produce melt extruded films. Starch is a biopolymer that can be gelatinized to form thermoplastic starch (TPS). The gelatinization is carried out in an extruder by applying shear and heat in presence of plasticizers. The influence of the TPS composition on the final properties of the films will be investigated. The crystalline structure, the mechanical properties and water solubility will be evaluated.

EFFECTS OF PC-OLIGOMER ADDITION ON THE MECHANICAL PROPERTIES OF ULTRA-HIGH SPEED INJECTION-MOLDED PC/ABS BLENDS
Toshikazu Umemura , Susumu Takashima , Machiko Mizoguchi , Hiroyuki Hamada, May 2010

Incorporation of low molecular weight components (oligomer) improves processability and surface appearance of injection moldings. Camera housings are commonly made from a compound consisting polycarbonate (PC) acrylonitrile-butadiene-styrene (ABS) PC-oligomer (PC-O) and glass fiber (GF). Even at high GF content smooth product surfaces can be obtained by incorporating PC-O. The addition of PC-O causes high fracture strain due to slippage between molecular chains and at the interphase. However an opposite tendency was observed in ultra-high speed (1000 mm/s) moldings as the ABS-rich region appeared to be highly elongated thus suggesting that there was less slippage at the interphase.

STRUCTURE-PROPERTY RELATIONSHIP OF WELD-LINE IN INJECTION MOLDED POLYPROPYLENE
Katsuyuki Yokomizo, Yoshihiro Banno, Masaya Kotaki, Hiroyuki Hamada, May 2010

Coarse-grained molecular dynamics simulation of a bead-spring polymer model was conducted for two polymer flow fronts flowing parallel to one another as would be found in a weld line. The effect of a molecular orientation of the flow fronts on the structure developed at the weld-line interface was studied by changing a shear flow and chain length. It was observed that the time evolution of the interfacial thickness was suppressed by shear flow for a long chain system. According to the calculation of the orientation order parameter of the bond vector as a function of the position along the chain, it was revealed that the bonds in the central part of the long chain was kept to be oriented more strongly than in the outer part, whereas the central part of the chain was quickly relaxed for short chain. It was suggested that the relaxation of molecular orientation was closely related to the interdiffusion of polymer in the weld interface.










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