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
ESTABLISHMENT OF A GAS-ASSISTED INJECTION MOLDING SYSTEM FOR WAX INJECTION IN INVESTMENT CASTING
Shia-Chung Chen, Yi-Chang Lin, Yu-Chin Lin, Chih-Chung Hsu, Venny Yang, Fu-Hung Hsu, May 2012
This study combines two processes. A one dimensional tube was used to investigate the gas penetration characteristics including penetration length and hollowed-core ratio under varied parameters including gas delay time, short shot and wax temperature. The wax properties were tested by importing the CAE software to simulate the wax filling and gas penetration length. The experimental results show gas-assisted injection molding is successfully applied to wax injection. Simulation results for wax filling and gas penetration are in agreement with the experimental results except for gas pressure, due to the viscosity deviation.
FUNCTIONALITY IN MULTILAYER FILMS FOR PACKAGING
F. Sadeghi, R. Silverwood, A. Housni, A. Ajji, May 2012
During the last decades, the food, pharmaceutical and many other industries have seen several changes in packaging technology and applications because of new consumer demands and market trends. These drivers can be summarized as requirements for high quality, freshness and extended shelf-life of products, with easy-to-use and resistant packaging made with lighter, cheaper and recyclable materials. On the other hand, public demand and awareness for food safety has become a significant concern. This has even intensified on the recent regular outbreak of Listeria and Salmonella bacteria in various area of the world, following the consumption of contaminated meat and cheese products. The outbreak has prompted the public awareness to question food quality in stores and technological solutions that could prevent contamination and/or alert consumers may provide better public protection. Finally, the global market for materials and films used in packaging is very large. When decomposed into various segments such as controlled, active, and smart or barrier packaging, the volumes used and annual growth rates are significant in addition to other concerns such as sustainability. The performance of polymer films and multilayer packages are the result of the microstructure that is imparted to the material as a result of complex interactions between the resin and the thermo- mechanical history that it experiences during processing. This microstructure is strongly influenced by molecular parameters of the resins used (molecular weight, molecular weight distribution, branching, co-monomer type and content, etc.), their layout in multilayer structures and the additives used as well as the rheological, thermodynamic, thermal properties and the crystallization kinetics under the processing conditions. In the past, most of the studies were directed to the improvement of structural properties of films and multilayer structures (mainly mechanical: strength, tear, toughness etc...) and muc
A STUDY ON THE SCRATCH RESISTANT CHARACTERISTICS OF INJECTION MOLDED POLYCARBONATE PARTS
Hyuk Kim, M-Y Lyu, Dong Cheol Shim, Sang Hyun Park, Sung Hwoan Cho, Do Kim, May 2012
Polycarbonate (PC) is one of the engineering plastics and it has high mechanical properties and transparent characteristics. PC is widely used for the outer case of mobile electronic products and lamp covers for automobile, and so on. However it has a weakness in low surface hardness, which is a low scratch resistant property. Scratch resistant property is considered very important specially for the outer case usage. Scratch resistant property is evaluated by pencil hardness. It was observed that the pencil hardness of injection molded PC sheet was dependent of its surface roughness. The specimen having convex or concave shaped surface had high pencil hardness. Deformation and stress concentration on the specimen surface have been analyzed during the pencil hardness test through computer simulation. Convex and concave shaped surface showed small deformation compare with flat surface. This made pencil hardness high. The surface of injection molded product can be controlled by controlling mold surface. Consequently the high pencil hardness can be achieved by designing the surface roughness of mold surface.
NEW NON-HALOGEN FLAME RETARDED BIO-DERIVED POLYMER BLENDS DEVELOPMENTS
Jason Zhu, Jing Liu, Patricia Hubbard, Roger Avakian, May 2012
The use of polylactic acid (PLA) in durable applications such as appliances and computers has been limited by PLA’s inherent property shortcomings, such as low impact strength, low heat distortion temperature, and lack of flame retardancy. These issues have been overcome via blending with engineering plastics, applying new compatibilization technology and using unique flame retardant additives. The resultant compositions have an excellent balance between heat resistance, impact resistance and flame retardancy. One such composition achieves a UL 94 rating of V-0 at 1.6 mm thickness, a notched Izod impact value at room temperature up to 11.6 ft-lbs/in and also exceeds a threshold of 100°C in heat distortion temperature (HDT) at 66 psi load. This bio-derived blend with >30% bio-content has exceptional properties and has taken PLA into the realm of engineering plastics. These enhancements will enable PLA to replace petrochemical- based materials in many demanding durable applications.
OBSERVATION AND ANALYSIS OF DEFROMATION AND FAILURE MECHANISMS OF ORIENTED POLYMERIC FOAM MATERIALS
Byoung-Ho Choi, Alexander Chudnovsky, May 2012
Various models of foam deformation have been formulated during last decade, but most of the models make use of basic concepts of continuum mechanics in combination with finite element method with limited consideration of specific micro-mechanisms of foam deformation and fracture. Three types of deformation and fracture mechanisms of oriented foams were classified: 1) Large reversible deformation, 2) Large elasto-plastic deformation and 3) Brittle fracture of faces and/or edges of individual cells. In this paper, five polymeric materials which have completely different deformation behaviors are selected and their fracture behavior was observed by scanning electron microscope. Among them, three polymeric foams with distinctively different deformation and fracture mechanisms are selected based on the classification for detail analyses.
THE EFFECT OF GLASS FIBER LENGTH ON ORIENTATION DISTRIBUTION WITHIN INJECTION MOLDED COMPOSITES
John Hofmann, Gregorio Velez-Garcia, Kevin Meyer, Abby Whittington, Don Baird, May 2012
The Method of Ellipses has been applied to short and long fiber polymer composites to evaluate fiber orientation. The resulting orientation distributions are compared at various percentages of fill for injection molded center-gated discs. Preliminary results suggest that an increase in magnitude in fiber length leads to significantly reduced fiber orientation in the radial direction (Arr). There is little effect on the Arz component of the orientation tensor, however, except at large percentages of fill.
INTERPENETRATING POLYMER NETWORKS (IPNS)
none, May 2012
Individual polymers are known to exhibit a wide range of characteristics that can be manipulated physically, thermally, and chemically. Furthermore, combining these materials through various mixtures can extend the ranges in properties offered by polymers. An interpenetrating polymer network (IPN) is a typical example of a multi-component polymer material. These polymers are closely related to other multi-component materials, containing completely entangled chains, such as polymer blends, grafts and blocks copolymers. IPN is a multiphase polymer material comprising of two or more networks which are at least partially interlaced on a molecular scale but are not covalently bonded to each other and cannot be separated unless chemical bonds are broken. The most common classifications of IPNs are full- or semi-IPNs. Compositions in which one or more polymers are crosslinked and one or more polymers are linear or branched are semi-IPNs, when both polymers are crosslinked in full are full-IPNs. These concepts were developed in the 70’s, when several research groups studied different systems in some detail [1-4]. For example, the important commercial system developed by Fischer [5] in the early 1970s involved ethylene-propylene-diene monomers (EPDM) in combination with isotactic polypropylene. The result was a material with excellent energy- absorption capacity In recent years only limited research has been reported in this area. From the available literature it is possible to infer that IPNs possess several interesting characteristics when compared to normal polymer blends, because the varied synthetic techniques yield IPNs of such diverse properties that their engineering potential is vast. These networks exhibit dual phase continuity, meaning two or more polymers in the system form phases that are continuous on a macroscopic scale and the kinetics of formation of the individual networks and the process of phase formation (phase separation) influence the final properties
FAILURE CRITERIA AND CHARACTERISTICS OF HEAT-SEALED ALUMINUM/POLYETHYLENE LAMINATES
Ichiro Mitani, Makoto Nakamura, Yew Wei Leong, Yasuo Hashimoto, Reiichi Konishi, Kazushi Yamada, Hiroyuki Hamada, Ken Miyata, May 2012
Failure criteria of the heat sealed part of aluminum (Al) and linear low density polyethylene (LLDPE) laminates made by an impulse type heat-sealing machine were investigated. Heat-sealing was performed in the machine and transverse directions with reference to the orientation of the aluminum sheet. The Al/LLDPE laminates consist of three layers, i.e. one sheet of aluminum as the outermost layer, which provides the strength and rigidity, and two sheets of LLDPE oriented in perpendicular directions, which make the laminates heat-sealable. Despite the presence of LLDPE films oriented in both directions, the direction of heat-sealing was found to affect the seal strength. This indicates that the heat-seal strength is primarily dependent on the molecular orientation of the LLDPE films at the seal interface.
THE EFFICIENCY EVALUATION FOR FRESNEL LENS OF CONCENTRATING SOLAR CELL WITH VARIOUS INJECTION MOLDING PROCESS
Shia-Chung Chen, Wei-Yao Hsu, Sung-Wei Huang, Hsin-Shu Peng, May 2012
In the recent years, with the increasing demand of energy and the rapid consumption of fossil fuels, a variety of alternative energy are rapid development to replace traditional energy. Solar power, is one of the best sustainable energy and nowadays widely used for generating electrical power. In this study, the solar condenser of converted efficiency is investigated into conventional and injection compression molding process with various parameters. The experimental results show that the higher mold and melt temperature can increase converted efficiency of condenser during conventional injection molding (CIM) process. In all conventional molding parameters, the best converted efficiency can enhanced 51.4 W/m2 (7.60%). The injection compression molding (CIM) can achieve better efficient performance than conventional molding process.
ENTRANCE DESIGN OF GAS-ASSISTED MOLD TEMPERATURE CONTROL AND ITS’ APPLICATION ON DOUBLE SIDE MICRO MOLDING
Jen-An Chang, Shia-Chung Chen, Wen-Ren Jong, Yung-Hsiang Chang, Sung-Wei Huang, May 2012
In this study, a gas-assisted heating system for mold surface temperature control was established. Two gap size control modes (A and B) of the gas channel and the heating results of both cavity and core sides were investigated, moreover, the effective heating area for gas heating expansion angle were determined as well by using gas flow rate 300l/min. The results show that the mold temperature difference on the gas inlet of core and cavity surface can be reduced from 39.8 °C to 1.4 °C under 5mm gap size with B mode. For the hot gas heating expansion angle, it directly affected heating area, and being relative with the entrance of gas channel. A case study of micro-molding for double sides 0.4mm thin wall plat (L/t=200) with micro-dot arrays shows that replication accuracies reach higher than 90% when molding at a mold temperature of 150 °C, an improvement of 25.3% over injection molding at the regular mold temperature of 90 °C.
COPOLYMER POLYOXYMETHYLENE PERFORMANCE IN AGGRESSIVE FUELS
Jeremy Klug, May 2012
Polyoxymethylene (POM) or polyacetal is an engineering thermoplastic resin used for the past 50 years, primarily in injection molded articles. POM’s benefit is derived from its strength, stiffness, toughness, lubricity and inherent chemical resistance. This combination of properties makes POM a preferred material for fuel exposure applications — both gasoline and diesel. This paper explores the influence of aggressive fuels on the properties of several commercial POM grades. Specifically, this work reports on the performance of POM exposed to different hydrocarbon-ethanol blends and to various low-sulfur diesel-biodiesel blends.
PART OF FOAMING CONTROL AND MECHANICAL PROPERTIES DURING MICROCELLULAR INJECTION MOLDING PROCESS VIA A SYSTEM OF GAS COUNTER PRESSURE AND DYNAMIC MOLD TEMPERATURE VARIATION
Shia-Chung Chen, Shin-An Lai, Yu-Tseng Lin, Yu-Lun Xiao, May 2012
The purpose of this study is to develop a foaming control for Gas Counter Pressure (GCP) combined with mold temperature control technology during the MuCell process and to investigate its influence on mechanical properties. The results show that under GCP control alone, foam qualities and the thickness of frozen layer may be affected. Further, the tensile strength increases, but impact strength falls. The lower the mold temperature control for the frozen layer, the more obvious is the increase in bubble size, while the greater the average bubble size, the lower the tensile strength. Using both GCP and the mold temperature control, when mold temperature was higher while get average bubble size small and uniform, resulting in improved tensile strength.
SPECIALTIES OF THE PROCESSING OF PLA THROUGH EXTRUSION AND INJECTION MOLDING, AND RESULTING CHARACTERISTICS
Andrea Siebert-Raths, Hans-Josef Endres, Sicco de Vos, May 2012
Next to the established packaging market the interest for biopolymers in technical application increases more and more. Especially the technical industry is interested in substituting oil-based polymers with biopolymers. In view of that, the focus of the work described here was on optimization of injection molding of polylactide (PLA) in order to improve material performance for technical applications. Furthermore, the effects of poly-D-lactide (PDLA) as nucleating agent, fibers and modifiers on material properties (e.g. heat resistance, mechanical properties) are reported.
EXECUTION OF 3 LEVEL FULL FACTORIAL DESIGN TO EVALUATE THE PROCESS PARAMETRS: POLYMER COLOR
Jamal Alsadi, Shahid Ahmad, Usman Saeed, Ghaus Rizvi, Daniel Ross, Richard Clarke, James Price, May 2012
The foremost reason of incorporating pigments in polymers is to introduce color either for aesthetic reason or because of functional needs. For dispersion of these pigments, the optimization of extrusion process parameters is required. In present study, a regression model was generated to illuminate the effect of processing parameter on the color properties of polymers by employing a 3 level full factorial design for response surface. The three processing parameters were temperature; speed and feed rate during extrusion of polymer compounding. Design expert software was employed to carry out the experimental designs, statistical and numerical optimization. The analysis of variance (ANOVA) reveals that the color parameters L*, a* and b* are significantly influenced by the considered parameters. The optimization of L*, a* and b* indicates that they are closer to the required target values at 241.9°C, 737.6 rpm and 25.3 kg/hr.
STRUCTURE AND PROCESSING DESIGN OF JUTE SPUN YARN/PLA BRAIDED COMPOSITE BY PULTRUSION MOLDING
Anin Memon, Asami Nakai, May 2012
Currently, the light has shed on the green composite from the view point of environmental protection. Jute fibers are natural fiber superior on light weight, low cost and environmental friendly corresponding to the green composite materials. Meticulously, fibers of polylactic acid (PLA) thermoplastic biopolymer were micro braided around jute spun yarns and paralleled configuration with jute. The pultrusion experiments were done with jute/PLA yarns and combined with glass fiber yarns to fabricate the tubular composite. Impregnation quality was evaluated by microscope observation of the pultruded cross-sections. The flexural mechanical properties of the beams were measured. The jute/PLA tubular pultrude composite using the parallel configuration of yarn showed the highest bending strength 28.3 MPa and modulus 15.4 GPa with the filling ratio 130% and volume fraction 52%.
THE THREE DIMENSIONAL NUMERICAL ANALYSIS AND VALIDATION OF COMPRESSION MOLDING PROCESS
Sejiin Han, Xiaoshi Jin, Jin Wang, Franco Costa, Roy Bendickson, May 2012
In this paper, a program for the three-dimensional analysis of compression molding of thermoset composites has been developed. This program can predict the flow pattern as well as fiber orientation and length distribution. The simulation results were compared to the experimental results from an actual case. The results compared include short shots and fiber orientation. The fiber orientation images were obtained using a CT scanning. The comparison shows reasonable agreement between simulation and experiment.
NEXT GENERATION UV STABILIZED, IMPACT MODIFIED POLYACETAL COPOLYMER (POM) FOR AUTOMOTIVE INTERIOR APPLICATIONS
Bruce M. Mulholland, May 2012
As presented at ANTEC 2010, a new family of impact modified Polyacetal copolymers (POM) have been developed that demonstrate improved stiffness, impact strength, and increased weld line performance compared to conventional impact modified POM grades. The unique properties have been achieved through the modification of the polymer backbone. Another drawback of conventional impact modified POM grades is generally poor UV performance, particularly for automotive interior applications. This paper discusses development of a next generation impact modified POM grade which exhibits a good balance of practical part toughness and UV stability in a broad range of colors to meet these demanding automotive interior applications.
NANOSTRUCTURED POLYMER SURFACES TO OPTIMIZE CELL BEHAVIOR
Clemens Holzer, Stephan Laske, Matthias Katschnig, M. Kracalik, May 2012
Recently, there has been growing interest to fabricate polymeric nano-structured surfaces with the ability to manipulate and control specific cell functions like proliferation, migration and differentiation. The nano-surface imitates the extracellular matrix, whose topography interacts in vivo with the cells and regulates their activity and morphology. The possibility to optimize the tools for tissue engineering and regenerative cell cultivation will be highly interesting for both the biomedical and polymer processing research and industry. Basic requirement for cells to interact with a surface is sufficient adhesion. Hydrophilic surfaces are known to increase adhesion, so in the first place the polymer surfaces were Corona-treated to enhance hydrophilicity. So in the beginning the target was to examine the Corona impact on unstructured polymer regarding to hydrophilicity (contact angle, surface energy) and surface chemistry (XPS). The results are presented in this work. It can be said that due to the Corona treatment all contact angles decrease with or without UV sterilization, which is equivalent to an increase of hydrophilicity. Furthermore the compared commercial products can be outreached concerning hydrophilicity by choosing appropriate Corona outputs. Hydrophobic recovery did not reach an equilibrium state, but after 10 weeks surface activation is still comparable to commercial references. XPS demonstrated that as result of the oxidation reactions due to Corona treatment polar groups containing oxygen are implemented in the surface. In future the outcome of this work will be combined with the impact of treated unstructured surfaces on cell behavior giving base knowledge, before the influence of nano-structures on cells is determined.
BIO COMPATIBLE FLUOROPOLYMERS AND ADVANCES IN INJECTION MOLDING THESE MATERIALS FOR MEDICAL DEVICES, DRUG DELIVERY SYSTEMS AND STORAGE COMPONENTS
Ken Kelly, May 2012
Injection molded fluoropolymers provide the chemical resistance and material performance needed for the manufacturing, storage and delivery of next generation cancer and biologic drug technologies. Fluoropolymers barrier properties, thermal properties and low surface adhesion characteristics offer advantages for powder and viscous liquid manufacturing, storage and delivery components. In the past, fluoropolymer were not often considered for high volume parts with complex geometries due to injection molding process limitations. Developments in mold design and tooling steels combined with new manufacturing equipment and processing techniques now allow the use of these biocompatible materials for high volume drug storage and delivery components.
IMPROVING THERMAL EFFICIENCY OF SINGLE SCREW EXTRUSION
Adrian Kelly, Javier Vera Sorroche, Elaine Brown, Phil Coates, May 2012
Thermal issues associated with polymer melt extrusion are complex. The process efficiency associated with melting and conveying polymers using a rotating screw inside a barrel is highly dependent upon the frictional, thermal and rheological properties of the polymer, the selected screw geometry, and designated extruder operating conditions including machine set temperatures and screw speed. Melting of the polymer is attained through a combination of thermal conduction and viscous shearing. This process is energy intensive but optimisation cannot be simply indicated by the energy used per kilogram of product. The quality of the extrudate is also of paramount importance. Melt quality can be defined in terms of the value and homogeneity of melt temperature. In this work, in- process monitoring techniques incorporating thermocouple grid sensors, infra-red thermometers and an energy meter have enabled real-time characterisation of thermal dynamics in single screw extrusion, for a 63.5mm diameter extruder. Operation of this extruder has also been simulated using commercial CAE software. Two commercial grades of polyethylene have been investigated using three extruder screw geometries at different extrusion operating conditions to gather evidence relating to process thermal efficiency. Extruder screw geometry, screw rotation speed, extruder set temperatures and material properties were each found to have a significant effect on the thermal homogeneity of the melt and on process energy consumed.
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