SPE Library
The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.
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Conference Proceedings
THE USE OF WATER CONTAINING TPO/ACTIVATED CARBON IN INJECTION MOLDING
Rachmat Mulyana, Thomas Daniel, Yong Min, Jose M. Castro, L. James Lee, May 2010
In injection molding, cycle time and sink mark are critical factors for process economics and product quality. This work focuses on reducing cycle time and sink part by utilizing water containing polymer/activated carbon pellets. Pellets were prepared by compounding a microparticle, activated carbon (AC) via extrusion, followed by a batch process of pressurizing a small amount of water into the pellets under controlled pressure and temperature. The amount of water, packing pressure and packing time were varied in the injection molding experiment. Preliminary results showed that the cycle time could be reduced to half and part shrinkage substantially decreased at a lower packing pressure without losing mechanical properties when the water content was low (e.g. 0.3 wt %). However, too much water (e.g. 2 wt %) tended to reduce mechanical properties even though the cycle time could be further reduced. We are in the process of tailoring the process conditions for optimized results, as well as evaluating the effect of residual water on the long-term properties of molded parts.
IMPROVED MECHANICAL PROPERTIES AND PRODUCT PERFORMANCE FOR IMPACT MODIFIED POLYOXYMETHYLENE CO-POLYMERS
Sarah Chung, Tieqi Li, Ken Oliphant, Patrick Vibien, May 2010
Ticona has developed a new family of impact modified polyoxymethylene (POM) co-polymers that demonstrate a combination of improved stiffness, impact strength, and up to a 290% increase in weld line performance compared to similar commercially available impact modified POM co-polymers. The unique properties of the new products have been achieved through the modification of the polymer backbone. The new grades provide enhanced product performance, up to 30% faster cooling time, and less mold deposit for a variety of injection molding and extrusion applications.
CHARACTERIZING LONG-TERM PERFORMANCE OF PLASTIC PIPING MATERIALS IN POTABLE WATER APPLICATIONS
Sarah Chung , Tieqi Li , Ken Oliphant , Patrick Vibien, May 2010
Plastic piping materials confer many advantages in Potable Water applications and have enjoyed a long and successful application history. Part of that success has been the considerable research that has been conducted to develop methodologies for characterizing and ensuring service performance. A key component of accelerated methodologies is ensuring that the observed mechanisms are the same as those potentially occurring in the field. In this paper field exposed plastic piping materials from aggressive applications are examined to determine the aging mechanisms observed in end-use environments.These mechanisms are compared with those observed in accelerated testing.
THE EFFECTS OF METAL PARTICLE SIZE AND DISTRIBUTIONS ON DIMENSIONAL ACCURACY FOR MICRO PARTS IN MICRO METAL INJECTION MOLDING
Kenji Okubo , Shigeo Tanaka , Hiroshi Ito, May 2010
This study aims to develop processing techniques to improve dimensional accuracy of micro-size parts produced by micro metal injection molding (?¬-MIM).Micro dumbbell specimens were molded by a micro injection molding machine, which can monitor the cavity pressure in injection molding process. The effects of particle size and distribution of metal powder on dimensional accuracy of micro dumbbell specimens at both grip parts were investigated. As the results, it is confirmed that the powder properties and sintering conditions to improve the dimensional accuracy of micro- MIM parts.
EFFECT OF CROSSLINKING ON THE SOLUBILITY OF N2 IN ETHYLENE-VINYL ACETATE (EVA)
Nan Chen , Mohammad Monirul Hasan , Takashi Kuboki , Chul B. Park, May 2010
In this paper, the effect of the crosslinking degree on the solubility of N2 in Ethylene-Vinyl Acetate (EVA) was investigated. Determining the solubility of the blowing agent is crucial for achieving fine-cell products in both the continuous and batch foaming processes with crosslinking. The variation of the crosslinking degree was controlled for the EVA samples, and a magnetic suspension balance (MSB) was employed to run the sorption tests. The solubility results were analyzed and discussed based on the experimental data.
INTERPHASE CNT TRANSFER USING LAMINATED POLYMER SHEETS
Howon Yoon , Kenzo Okamoto , Masayuki Yamaguchi, May 2010
Carbon nanotubes (CNT) are a great candidate to obtain a conductive path in a polymer matrix with a small amount, because it has large aspect ratio. The purpose of this study is to localize CNT at polymer surface by annealing procedure employing laminated sheets composed of an immiscible polymer pair, in which one component contains CNT and the other does not. It was found that CNT transfer occurs by Brownian motion from the composite with CNT to the surface of the pure polymer. As a result, the pure polymer obtained after the separation from the laminated sheets exhibits electrical conductivity owing to the conductive path of the CNT localized at the surface.
PLATE ACTUATED HOT RUNNER VALVE GATES FOR IMPROVED PART QUALITY AND MOLDING PROCESS CONSISTENCY
Stephen Gray , Abdeslam Bouti, May 2010
The high growth in the medical market along with the increased demand for high standards in injection molding in the last five years have lead to the emergence of a new class of valve gate hot runner that provides better molding process consistency along with unmatched part quality. This new valve gate hot runner uses a plate to couple valve stems to allow them to be driven by a hydraulic or electrical actuator. The coupling enables synchronicity of stem movement and the drive provides consistent high force. This paper presents this new hot runner technology that found a niche in stringent applications such as small part molding and the medical market.
RESEARCH ON RESIDUAL STRESSES OF INJECTION MOLDED PC PARTS
Haimei Li , Yiyan Peng , Lih-Sheng Turng , Xin Wang, May 2010
Residual stresses in injection molded parts may have negative effects on optical and mechanical properties. It is usually two types residual stresses in the injection molded parts - flow-induced and thermally-induced stresses. In this paper thermal residual stresses are investigated by comparing tensile properties of the injection molded PC parts before and after annealing. A dielectrostrictive sensor is developed to conduct the flow-induced stress analysis during filling stage. The physical meaning of obtained dielectrostriction signals is given based on the experimental and numerical results. First the pressure measured by the transducers was compared with the numerical simulated results. These two values agree well which indicates that the numerical prediction should also be reliable for shear stress analysis. Then the shear stress calculated based on the measured dielectrostriction signal was compared with its corresponding numerical result. And it has been found that the difference between these two values within 5% at the various processing condition.
RESEARCH ON RESIDUAL STRESSES OF INJECTION MOLDED PC PARTS
Haimei Li , Yiyan Peng , Lih-Sheng Turng , Xin Wang, May 2010
Residual stresses in injection molded parts may have negative effects on optical and mechanical properties. It is usually two types residual stresses in the injection molded parts - flow-induced and thermally-induced stresses. In this paper, thermal residual stresses are investigated by comparing tensile properties of the injection molded PC parts before and after annealing. A dielectrostrictive sensor is developed to conduct the flow-induced stress analysis during filling stage. The physical meaning of obtained dielectrostriction signals is given based on the experimental and numerical results. First the pressure measured by the transducers was compared with the numerical simulated results. These two values agree well, which indicates that the numerical prediction should also be reliable for shear stress analysis. Then the shear stress calculated based on the measured dielectrostriction signal was compared with its corresponding numerical result.And it has been found that the difference between these two values within 5% at the various processing condition.
STUDY OF PROCESSING PARAMETERS ON PART WARPAGE OF INMOLDPOLLER INJECTION MOLDING INJECTION MOLDING
H. C. Chen , S. C. Chen , P.M. Hsu , H. S. Peng , Y. C. Wang, May 2010
In-mold roller (IMR) injection molding is one of the commonly used In-Mold Decoration technology for ink transfer. The effect of processing parameters on part‘s warpage is very important for product quality. In this study the PET film with thickness of 0.05mm and 0.036mm is molded and computer simulation analysis is performed to compare the result with experiment. It was found that high melt temperature and thick film would result in heat stagnation between surface-frozen layer and film interface leading to a large part’s warpage. However a high mold temperature resulted in a low warpage. For IMR molding the mold temperature difference between core and cavity surface was about 6.71~12.94? and the warpage varied from 0.15mm to 0.91mm under specified conditions.
STUDY OF PROCESSING PARAMETERS ON PART WARPAGE OF IN-MOLDPOLLER INJECTION MOLDING
H. C. Chen , S. C. Chen , P.M. Hsu , H. S. Peng , Y. C. Wang, May 2010
In-mold roller (IMR) injection molding is one of the commonly used In-Mold Decoration technology for ink transfer. The effect of processing parameters on partƒ??s warpage is very important for product quality. In this study, the PET film with thickness of 0.05mm and 0.036mm is molded and computer simulation analysis is performed to compare the result with experiment. It was found that high melt temperature and thick film would result in heat stagnation between surface-frozen layer and film interface leading to a large partƒ??s warpage. However, a high mold temperature resulted in a low warpage. For IMR molding, the mold temperature difference between core and cavity surface was about 6.71~12.94ƒ?Ÿ and the warpage varied from 0.15mm to 0.91mm under specified conditions.
MODELING MOLD CAVITY TEMPERATURE USING ARTIFICIAL NEURAL NETWORK PARAMETER ESTIMATION TECHNIQUES
Scott E. Everett, Mauricio J. Hernandez, Rickey Dubay, May 2010
In injection molding, final product quality is influenced by the cycle average mold cavity temperature, which depends on the mold coolant flow-rate. The design of a generic average temperature controller is difficult due to the nonlinear characteristics of the in-mold part cooling process. In this investigation, the parameters of a lumped-model are obtained using artificial neural network techniques to develop a generic model-based control scheme that can be implemented in a variety of molds with minimal open loop testing.
MODELING MOLD CAVITY TEMPERATURE USING ARTIFICIAL NEURAL NETWORK PARAMETER ESTIMATION TECHNIQUES
Scott E. Everett , Mauricio J. Hernandez , Rickey Dubay, May 2010
In injection molding final product quality is influenced by the cycle average mold cavity temperature which depends on the mold coolant flow-rate. The design of a generic average temperature controller is difficult due to the nonlinear characteristics of the in-mold part cooling process. In this investigation the parameters of a lumpedmodel are obtained using artificial neural network techniques to develop a generic model-based control scheme that can be implemented in a variety of molds with minimal open loop testing.
CORE MORPHOLOGY OF PBS ALLOYS AND PROPERTIES OF PP-BASED SANDWICH INJECTION MOLDINGS
Yuji Fujita , Naoya Aoki , Toshihiro Yoshida , Hironari Sano , Masaya Kotaki, May 2010
Polypropylene (PP)-based sandwich injection moldings with polybutylene succinate (PBS) alloys in core were studied. Different core morphologies of PBS/PP alloys were obtained by changing content and melt flow rate (MFR) of PBS and core-PP, and injection molding conditions. It was found that the core morphologies significantly affected skin/core interfacial adhesion and mechanical properties of the sandwich injection moldings. The spreading index considering dynamic viscosity and volume fraction of PBS and core-PP was proposed to discuss the mechanism of the core morphology development. Scratch and Izod impact tests according to ASTM standards were performed to investigate the effects of skin/core adhesion on scratch and impact characteristics.The sandwich injection moldings with poor skin/core adhesion caused the skin/core delamination upon the scratch and Izod impact tests.
IMPROVEMENT OF MECHANICAL PROPERTIES OF AN ALL RENEWABLE BASED WOOD-RESIN COMPOSITE
Rahul M. Rasal, Douglas E. Hirt, May 2010
Impregnation of linseed epoxy resin into softwood creates an all-renewable composite. This composite is intended to be a substitute for expensive hardwoods used in applications such as decking and flooring. Initial epoxy impregnation was conducted within a custom vacuum-pressure chamber with positive results. The impregnation process begins with an initial vacuum treatment to remove the air inside the wood, followed by the use of pressure to drive the resin into the wood under certain temperature conditions. This process was improved by optimizing vacuum-pressure levels and temperature, as well as the use of a high temperature curing agent. In this way, superior impregnation depths were obtained. The final result was a composite material with better mechanical properties than both the resin and the softwood themselves. Specifically, the impregnated samples showed Youngƒ??s modulus over three times higher than those of unimpregnated wood samples, in both tension and compression. Furthermore, the hardness of the wood increased significantly; depending on impregnation depth, hardness reached and surpassed 4500 lbf, the estimated value of Lignum Vitae, the hardest wood available. Secondary testing focused on automation of the initial process in order to facilitate optimized impregnation on an industrial scale. A custom multi-chambered impregnation machine was designed to perform a continuous impregnation.
THE OPTIMIZATION OF HIGH INORGANIC CONTENT HYBRID BARRIER MATERIALS
Jing Wang, Wenli Zhu, Chul B. Park, Jed Randall, May 2010
Much work has been done to model the behavior of platelet-filled hybrid barrier materials and produce high barrier polymer/nanoclay composites with low clay contents. Little has been done to test the applicability of these models over a wide range of clay contents and determine whether current systems are near ideal or could be further improved. In this work, cyclic olefin copolymers are combined with organically modified montmorillonite clay via a spray deposition technique to create transparent, highly aligned model hybrids containing up to 100% clay. The structure and properties of these sheets are then characterized via XRD, DMA and OPA.
IMPACT OF MOLECULAR BRANCHING ON MICROCELLULAR FOAMING OF POLYLACTIC ACID IN EXTRUSION
Jing Wang , Wenli Zhu , Chul B. Park , Jed Randall, May 2010
Microcellular foams of polylactic acids (PLA) with and without molecular branching were produced on a tandem extrusion system using carbon dioxide as the physical blowing agent. Cell density and expansion ratio were found to be strong functions of the molecular structure the blowing agent content and the processing temperature. Very low density foams were produced with the branched PLA at the optimal processing condition while the linear PLA exhibited severe cell opening beyond a reasonable expansion ratio. Very low crystallinity was detected in the foamed samples indicating that shearing and the presence of supercritical carbon dioxide in the extrusion system did not induce crystal growth.
IMPACT OF MOLECULAR BRANCHING ON MICROCELLULAR FOAMING OF POLYLACTIC ACID IN EXTRUSION
Jing Wang , Wenli Zhu , Chul B. Park , Jed Randall, May 2010
Microcellular foams of polylactic acids (PLA), with and without molecular branching, were produced on a tandem extrusion system using carbon dioxide as the physical blowing agent. Cell density and expansion ratio were found to be strong functions of the molecular structure, the blowing agent content, and the processing temperature. Very low density foams were produced with the branched PLA at the optimal processing condition, while the linear PLA exhibited severe cell opening beyond a reasonable expansion ratio. Very low crystallinity was detected in the foamed samples, indicating that shearing and the presence of supercritical carbon dioxide in the extrusion system did not induce crystal growth.
DEPTH SENSING NANO-INDENTATION TECHNIQUE TO ASSESS DEGRADATION OF WEATHERED POLYMER SURFACES
Lei-Ti Huang, Ping-Shun Hsu, Shia-Chung Che, May 2010
Measurement of surface appearance often fails to predict mechanical failure while bulk mechanical testing confirms failure only after prolonged exposure in weathering. In this study, we attempt to detect small changes in surface mechanical properties during initial stages on the weathered surface of polycarbonate-based materials using surface sensitive nano-indentation technique. Samples were also characterized using various techniques including transmission electron microscopy and infrared spectroscopy. Information on the degradation layer thickness may help in assessing mechanical failure of polymer during early stages. Studies show the superiority of Lexan* SLX resin over polycarbonate in weathering.
THE GENERATION OF THE PTFE POROUS STRUCTURE INDUCED BY UNIAXIAL STRETCHING PROCESS WITH ASYMMETRIC HEATING OPERATION
Lei-Ti Huang , Ping-Shun Hsu , Shia-Chung Che, May 2010
Polytetrafluoroethylene (PTFE) is a remarkable membrane material. Due to its high melting point, PTFE cannot be processed using the conventional melting processing methods. In addition, porous materials have been used in many industrial technologies and life surroundings. Plastic expansion technology has created a new class of filter material, called expanded PTFE (ePTFE). The material comprises a highly fibrillated and porous microstructure that contributes to its excellent filter capability. In this paper, different stretching ratio, asymmetry heating temperature, and different heating time was used to modify the ePTFE membrane pore size. It was found that a longer heating times and lower stretching times, the porosity of PTFE membrane was increased from 30 to 70% and the mean pore size was decreased from 0.22 to 0.08 ?¬m.
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