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Conference Proceedings

THE EFFECT OF SCREW DESIGN ON THE QUALITY OF INJECTION MOLDING PRODUCTS

Shai Barkai , Samuel Kenig, May 2008

The melt quality and its effect on the final product quality is one of the least studied subjects in the process of injection molding. Consequently, the present study is aimed at investigating the plastification stage in injection molding. A general-purpose screw and a barrier type screw were studied with respect to the effect of melt temperature, back pressure and screw rotation speed on product quality. Results indicated that the melt temperature and the back pressure are the decisive factor in the case of the general-purpose screw and the barrier screw, respectively. Due to the longer residence times in barrier type screws, lower temperatures should be used to avoid melt degradation and inferior mechanical properties.

AN EVALUATION OF DIFFERENT INJECTION MOLDING SCREW DESIGNS AND THEIR EFFECT ON MIXING QUALITY USING AN INLINE MELT CAMERA (I.M.C)

Luke M. Miller , Walter S. Smith , Timothy W. Womer, May 2008

Improved color mixing for injection molding can be improved by different variables. Screw speed melt temperature back pressure barrel temperature profiles screw design dispersion discs etc. can all influence color dispersion. The mixing ability of an injection molding screw is an important element in the finished part quality of a part which is why screw design is the focus of this study. An I.M.C will allow examination of the molten melt stream prior to exiting the die to give a quantitative comparison of different injection molding screw designs.

PREPARATION AND PROPERTIES OF DYNAMICALLY CURED PE/MAH-G-SEBS/EPOXY BLENDS

Xueliang Jiang , Yinxi Zhang, May 2008

A new method concerning with the simultaneous reinforcing and toughening of polypropylene (PP) was reported. Dynamical cure of the epoxy resin was successfully applied in the PP/maleic anhydride-grafted styrene-ethylene butylenes-styrene (MAH-g-SEBS) triblock copolymer and the obtained blends named as dynamically cured PP/MAH-g-SEBS/epoxy blends. The stiffness and toughness of the blends are in a good balance and MAH-g-SEBS was acted as not only an impact modifier but also a compatibilizer. The structure of the dynamically cured PP/MAH-g-SEBS/epoxy blends is the embedding of the epoxy particles by the MAH-g-SEBS.

PREPARATION AND PROPERTIES OF DYNAMICALLY CURED PE/MAH-G-SEBS/EPOXY BLENDS

Xueliang Jiang , Yinxi Zhang, May 2008

A new method concerning with the simultaneous reinforcing and toughening of polypropylene (PP) was reported. Dynamical cure of the epoxy resin was successfully applied in the PP/maleic anhydride-grafted styrene-ethylene butylenes-styrene (MAH-g-SEBS) triblock copolymer, and the obtained blends named as dynamically cured PP/MAH-g-SEBS/epoxy blends.The stiffness and toughness of the blends are in a good balance, and MAH-g-SEBS was acted as not only an impact modifier but also a compatibilizer.The structure of the dynamically cured PP/MAH-g-SEBS/epoxy blends is the embedding of the epoxy particles by the MAH-g-SEBS.

VVARIABLE MOLD TEMPERATURE FOR IMPROVING SURFACE QUALITY OF MICROCELLULAR INJECTION MOLDED PARTS USING INDUCTION HEATING TECHNOLOGY

Shia-Chung Chen , Jeng-Sheng Huang , Ping-Shun Hsu , Jui-Pin Yang , Ho-Hsiang Wang, May 2008

In this study a variable mold temperature method via induction heating combined with water cooling was used to improve surface quality of microcellular parts. It was found that the surface roughness can decreases from 25?¬m to 6.5?¬m when mold surface temperature increases from 100?øC to 160?øC. The flow marks of gas bubbles on the part surface can be removed completely at mold temperature of 160?øC. When the mold temperature over a critical value about 180?øC the surface roughness can reach a saturated value about 5?¬m. Compared to conventional water heating with initial In 60?øC mold temperature surface roughness can be greatly improved by about 80% without a significant increase in cycle time.

EVALUATION OF MOLECULAR ORIENTATION IN POLYSTYRENE BY LASER RAMAN SPECTROSCOPY

Koji Yamada , Kiyotaka Tomari, May 2008

Molecular orientation in injection molded polystyrene was investigated by polarized laser-Raman spectroscopy. The relative intensity ratio of two specific peaks in a spectrum was determined as Orientation Index Ior in accordance with an earlier report. Two kinds of orientation peak along the depthwise direction were found in a section of the molded specimen. This result is qualitatively consistent with the orientation model presented by Tadmor. Polarized laser-Raman spectroscopy was applied to a weldline region in which molecular orientation is supposed to be one of main factors to reduce its mechanical properties. The degree of molecular orientation increased along the flow direction in the case of adjacent flow weldline occurring behind an obstructive pin in the flow channel. This means that the orientation along the weldline in the area near the pin is relatively low. The tensile strength of the area nearest to the pin was higher than that of the downstream area despite the fact that the surface V-notch was deepest. This fact insists that the molecular orientation affects significantly to the mechanical properties of weldline in injection moldings.

EFFECTS OF SOLVENT-CASTING CONDITIONS ON THE MORPHOLOGY AND PROPERTIES OF DISULFONATED POLY (ARYLENE ETHER SULFONE) COPOLYMER FILMS FOR POLYMER ELECTROLYTE MEMBRANES

Myoungbae Lee , Ozma Lane , James E. McGrath , Donald G. Baird, May 2008

Disulfonated poly(arylene ether sulfone) (BPSH) copolymers have been shown to be potentially useful in the generation of polymer electrolyte membranes (PEMs) in fuel cells. In our work we find that solvent-casting conditions such as solvent type drying temperature and initial polymer concentration significantly affects the morphology and properties of PEMs produced by means of film casting. The design of the solvent removal process requires a knowledge of the kinetics of phase separation which occurs during the drying process. Block copolymers are found to be much more sensitive to drying conditions than the random copolymers.

THE EFFECT OF VIBRATION ON CELL MORPHOLOGY OF PC FOAM

Ming Yi Wang , Nan Qiao Zhou , Gang Jin , Sheng Ping Wen, May 2008

The purpose of this research is to investigate the effect of vibration on cell morphology of PC foam. In this study foamed PC was produced using a dynamic simulation foaming setup designed by ourselves with supercritical CO2 as foaming agent. Cell morphology was compared as vibration frequency varied from 2.5Hz to 10Hz and vibration amplitude varied from 25? m to 100 ? m respectively under the same condition. The cell morphology of foamed samples was characterized by using SEM. It was found that foamed samples with better cell morphology could be obtained as vibration frequency increased?foamed samples with better cell morphology could be obtained as vibration amplitude increased to 75 ? m then cell morphology became worse with further increase of vibration amplitude.

THE EFFECT OF VIBRATION ON CELL MORPHOLOGY OF PC FOAM

Ming Yi Wang , Nan Qiao Zhou , Gang Jin , Sheng Ping Wen, May 2008

The purpose of this research is to investigate the effect of vibration on cell morphology of PC foam. In this study, foamed PC was produced using a dynamic simulation foaming setup designed by ourselves, with supercritical CO2 as foaming agent. Cell morphology was compared as vibration frequency varied from 2.5Hz to 10Hz and vibration amplitude varied from 25?¬ m to 100 ?¬ m respectively under the same condition. The cell morphology of foamed samples was characterized by using SEM. It was found that foamed samples with better cell morphology could be obtained as vibration frequency increased‹¬?foamed samples with better cell morphology could be obtained as vibration amplitude increased to 75 ?¬ m, then cell morphology became worse with further increase of vibration amplitude.

CHARACTERIZATION OF BIODEGRADABLE ACRYLIC ACID GRAFTED POLY(?-CAPROLACTONE)/CHITOSAN BLENDS

Yeh Wang , Jiang-F. Yang, May 2008

Blend films of acrylic acid grafted polycaprolactone (PCLgAA) and chitosan (CS) with different compositions were prepared from aqueous acetic acid solution. DSC measurements showed that the melting temperatures and enthalpies of the blends decreased with increasing CS content. From FTIR results it can be seen that the amino groups of CS form covalent bonds with the carboxylic groups of PCLgAA in addition to hydrogen bonds between these components in the blends. Though the crystal structure of the PCLgAA component was not changed as proved by WAXD results blending CS suppressed the crystallinity of the blends. Furthermore the ductility of CS was increased during tensile testing in PCLgAA/CS blends due to enhanced affinity between the two components. However PCLgAA/CS blends showed greater resistance than PCL/CS blends to biodegradation in an enzymatic environment.

CHARACTERIZATION OF BIODEGRADABLE ACRYLIC ACID GRAFTED POLY(?-CAPROLACTONE)/CHITOSAN BLENDS

Yeh Wang , Jiang-F. Yang, May 2008

Blend films of acrylic acid grafted polycaprolactone (PCLgAA) and chitosan (CS) with different compositions were prepared from aqueous acetic acid solution. DSC measurements showed that the melting temperatures and enthalpies of the blends decreased with increasing CS content. From FTIR results it can be seen that the amino groups of CS form covalent bonds with the carboxylic groups of PCLgAA in addition to hydrogen bonds between these components in the blends. Though the crystal structure of the PCLgAA component was not changed, as proved by WAXD results, blending CS suppressed the crystallinity of the blends. Furthermore, the ductility of CS was increased during tensile testing in PCLgAA/CS blends due to enhanced affinity between the two components. However, PCLgAA/CS blends showed greater resistance than PCL/CS blends to biodegradation in an enzymatic environment.

STUDY ON THE RIB-DESIGNED PART SURFACE QUALITY MOLDED BY EXTERNAL GAS-ASSISTED INJECTION

Shia-Chung Chen , Chia-Yen Tseng , Chien-Chia Su, May 2008

This study investigates the surface quality of parts molded by external gas assisted injection. A flat ABS part was constructed 100 mm long 50 mm wide and 1.5 mm thick (designated T) with four different thicknesses of rib: 0.6T 0.8T 1T and 1.2T. Under external gas assisted molding process the sink mark for 1.2T rib design can be reduced from 26.88?¬m under conventional injection molding to 3.47?¬m. Combined with process condition optimization of parameters such as mold temperature gas pressure and packing time the sink mark can be further reduced (below 1?¬m). Increased cavity surface smoothness created by various polishing techniques also improves sink marks.

RHEOLOGICAL PROPETIES OF BRANCHED POLYSTYRENE PREPARED BY AN ULTRASOUND ASSISTED INTENSIVE MIXER

Hee Jung Kim , Hyungsu Kim , Hooseok Lee , Jae Wook Lee, May 2008

By combining ultrasonic energy which can cause chain scission of polymer molecules and a multifunctional agent (MFA) having double bonds at its ends we were able to modify the molecular structure of polystyrene (PS) from linear to a branched structure during melt processing. The three double bonds in chain ends of MFA were expected to act as sites for trapping macroradicals of PS during the course of ultrasound- assisted mixing process. The transformation of molecular structure of PS was confirmed by the measurements of rheological properties of the modified PS. After the ultrasonic irradiation of PS together with MFA increase in complex viscosities and shear-thinning behavior were observed. The Cole-Cole plot revealed the characteristic features of branched structure.

INSTRUMENTAL INVESTIGATIONS OF PHYSICAL GUMMIINESS OF A MEDICAL GRADE EPOXY-AMINE ADHESIVE AFTER CURING

Xiaoping Guo, May 2008

Various factors that might interfere with reaction stoichiometry and result in physical gumminess of the cured mass were investigated for a medical grade epoxy-amine adhesive system. Dynamic rheometry was used to probe the evolution of dynamic mechanical properties in the adhesive during isothermal curing and a Fourier-transform infrared spectrometer (FT-IR) was utilized to measure the degree of chemical conversion after curing. It has been found that physical gumminess of the adhesive cured under a selected normal curing condition was primarily due to the presences of excessive hardener and also liquid residuals of an industrial cleaner containing hydroxyl and amine functional groups while the presence of excessive epoxy resin at a moderate level arising from non-stoichiometric mixing is unlikely to cause physical gumminess of the cured adhesive mass. Accordingly it is considered that the selection of a proper cleaner and improvement of stoichiometric adhesive mixing prior to adhesive dispensing is of vital importance to developing reliable and strong adhesive bondlines.

INSTRUMENTAL INVESTIGATIONS OF PHYSICAL GUMMIINESS OF A MEDICAL GRADE EPOXY-AMINE ADHESIVE AFTER CURING

Xiaoping Guo, May 2008

Various factors that might interfere with reaction stoichiometry and result in physical gumminess of the cured mass were investigated for a medical grade epoxy-amine adhesive system. Dynamic rheometry was used to probe the evolution of dynamic mechanical properties in the adhesive during isothermal curing, and a Fourier-transform infrared spectrometer (FT-IR) was utilized to measure the degree of chemical conversion after curing. It has been found that physical gumminess of the adhesive cured under a selected, normal curing condition was primarily due to the presences of excessive hardener and also liquid residuals of an industrial cleaner containing hydroxyl and amine functional groups, while the presence of excessive epoxy resin at a moderate level arising from non-stoichiometric mixing is unlikely to cause physical gumminess of the cured adhesive mass. Accordingly, it is considered that the selection of a proper cleaner and improvement of stoichiometric adhesive mixing prior to adhesive dispensing is of vital importance to developing reliable and strong adhesive bondlines.

BREAKTHROUGH MATERIAL FOR LOW GLOSS AND ABRASION RESISTANCE WITH MOLDED-IN-COLOR AUTOMOTIVE INTERIOR COMPONENTS

Steve Rogers , Parvinder Walia , Norwin Van Riel , Jozef Van Dun , Tom Traugott, May 2008

The luxury impression of a vehicle’s interior is strongly determined by the surface quality of the plastic interior trim parts. In higher level vehicles this is achieved by covering the plastic surfaces with Polyvinyl Chloride (PVC) or Thermoplastic Olefin (TPO) skins fabrics or paint. However in the majority of cases cost constraints dictate the use of unpainted molded-in-color plastic parts. The critical factors that determine the quality of unpainted interior part surfaces are low gloss appearance along with good scratch and abrasion resistance. The typical materials currently in use for molded-in-color parts are Polypropylene talc-filled Polypropylene (TF-PP) talcfilled Thermoplastic Olefin (TF-TPO) Acrylonitrile Butadiene Styrene (ABS) Polyamide/ABS (PA/ABS) and Polycarbonate/ABS (PC/ABS). Through extensive development efforts over the past several years the performance of these materials has significantly improved with respect to scratch resistance and low gloss aesthetic appearance. However a significant gap in surface quality and robustness in comparison to the painted solution is still present. A development project aiming to reduce these specific deficiencies resulted in new innovative material formulations which provide breakthrough improvements in low gloss appearance with excellent scratch and mar resistance. The resulting new material family makes use of the latest advancements in elastomer technologies from Dow Automotive. Velvex™ an Advanced Reinforced Elastomer will enable the automotive OEM to realize significant cost savings through the elimination of paint in higher segment vehicle interiors or with aesthetically more demanding applications.

BREAKTHROUGH MATERIAL FOR LOW GLOSS AND ABRASION RESISTANCE WITH MOLDED-IN-COLOR AUTOMOTIVE INTERIOR COMPONENTS

Steve Rogers , Parvinder Walia , Norwin Van Riel , Jozef Van Dun , Tom Traugott, May 2008

The luxury impression of a vehicleƒ??s interior is strongly determined by the surface quality of the plastic interior trim parts. In higher level vehicles, this is achieved by covering the plastic surfaces with Polyvinyl Chloride (PVC) or Thermoplastic Olefin (TPO) skins, fabrics, or paint. However, in the majority of cases, cost constraints dictate the use of unpainted, molded-in-color plastic parts.The critical factors that determine the quality of unpainted interior part surfaces are low gloss appearance along with good scratch and abrasion resistance. The typical materials currently in use for molded-in-color parts are Polypropylene, talc-filled Polypropylene (TF-PP), talcfilled Thermoplastic Olefin (TF-TPO), Acrylonitrile Butadiene Styrene (ABS), Polyamide/ABS (PA/ABS), and Polycarbonate/ABS (PC/ABS). Through extensive development efforts over the past several years, the performance of these materials has significantly improved with respect to scratch resistance and low gloss aesthetic appearance. However, a significant gap in surface quality and robustness in comparison to the painted solution is still present. A development project aiming to reduce these specific deficiencies resulted in new innovative material formulations, which provide breakthrough improvements in low gloss appearance with excellent scratch and mar resistance. The resulting new material family makes use of the latest advancements in elastomer technologies from Dow Automotive. Velvexƒ?›, an Advanced Reinforced Elastomer, will enable the automotive OEM to realize significant cost savings through the elimination of paint in higher segment vehicle interiors, or with aesthetically more demanding applications.

PROCESSING OF PET NANOCOMPOSITES WITH DIFFERENT PERCENTAGE OF SURFACTANTS USING TWIN SCREW EXTRUSION TECHNOLOGY

K Tarverdi , S. Sontikaew, May 2008

In this study a light guide plate was designed using different micro features on a three-sided surface.Simulation software was applied to analyze the luminance of brightness and uniformity under various micro pattern designs so that a fair optical performance can be achieved.Then a micro-patterned mold was made for molding. The effect of replication accuracy on the brightness and the luminance uniformity resulting from molding was investigated. It was found the replication accuracy is increased with increasing mold temperature and melt temperature. When the replication accuracies of the Vgroove at three-side surface were improved the resulting luminance was also increased by 17.96 %.

PROCESSING OF PET NANOCOMPOSITES WITH DIFFERENT PERCENTAGE OF SURFACTANTS USING TWIN SCREW EXTRUSION TECHNOLOGY

K Tarverdi , S. Sontikaew, May 2008

Poly(ethylene terephthalate) (PET) nanocomposites and two organoclays with different content of the same surfactant were blended in a twin screw extruder. The effect of the amount of surfactant on the microstructure and isothermal crystallization kinetics of the filled and unfilled systems was studied. The isothermal data from differential scanning calorimetry was analyzed using the Avrami equation. The spherulitic structure was observed using scanning electron microscope. It was found that the amount of the surfactant significantly affected the crystallization and microstructure of PET/organoclay nanocomposite.

EFFECTS OF THE MECHANICAL PROPERTIES ON THE SCRATCH BEHAVIOR OF ABS COPOLYMER

Keehae Kwon , Il-Jin Kim, May 2008

The effects of the mechanical properties on the scratch resistance are investigated by using Ball-type Scratch Profile (BSP) test developed by Cheil Industries Inc. BSP test method is designed for evaluating the scratch resistance by quantifying the amounts of created scratch to scratch width depth range and area. To investigate the relation between scratch behavior and mechanical property the measured scratch width is compared with the mechanical properties such as tensile strength tensile elongation flexural strength and flexural modules. The Rockwell hardness and pencil hardness results are also compared with the measured scratch width and their relations are studies.