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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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MELT FRACTURE OF LINEAR POLYETHYLENES: MOLECULAR STRUCTURE AND DIE GEOMETRY EFFECTS
Mahmoud Ansari , Savvas G. Hatzikiriakos, May 2008
The melt fracture polymer extrusion instabilities are studied primarily as functions of the geometrical details of die (cylindrical, slit and annular) and molecular structure of polymers. Experimental observations concerning the flow curves, the critical wall shear/extensional stresses for the onset of the instabilities and the effects of geometry, and operating conditions are presented for two linear polyethylenes, mainly highdensity polyethylenes (HDPEs). It is found that sharkskin and other melt fracture phenomena are sensitive to details of the molecular weight distribution (MWD). It is also found that critical conditions for the onset of various melt fracture phenomena depend significantly on the type of die used for their study. For example, sharkskin melt fracture in slit and capillary extrusion was obtained at much smaller critical shear stress values compared to those found in annular extrusion. Such observations explain the lack of correlation between experimental results from the laboratory and the full scale process.
EXTRUSION-ASSISTED DIRECT-FOAMING ROTATIONAL MOLDING PROCESS
Kimberly Christian , Emad Abdalla , Gregory Eberle , Remon Pop-Iliev, May 2008
This paper focuses on the evolution and experimental validation of the novel patent-pending Extrusion-Assisted Rotational Foam Molding (EARFM) process intended for the fabrication of high quality integral-skin fine-celled foamed-core polyolefin moldings. The process innovatively conjoins the traditional rotational foam molding technology with extrusion melt compounding in a deliberate attempt to reduce the principal intrinsic disadvantages associated with rotational foam molding i.e. the energy intensive and very lengthy processing cycles. A lab-scale custom-made heavy-duty experimental setup along with three mold shape variations (cylindrical flat plate and container-like) have been designed and built. It was used for conducting a comparative experimental process validation by using all three mold designs for processing integral-skin foamed core polyethylene (PE) parts. The process control optimization included resin formulation optimization direct foaming concept implementation for process simplification and mold venting system re-design. The thereby modified process resulted in even shorter processing cycle times lower energy consumption and improved foam morphologies.
EXTRUSION-ASSISTED DIRECT-FOAMING ROTATIONAL MOLDING PROCESS
Kimberly Christian , Emad Abdalla , Gregory Eberle , Remon Pop-Iliev, May 2008
This paper focuses on the evolution and experimental validation of the novel patent-pending Extrusion-Assisted Rotational Foam Molding (EARFM) process intended for the fabrication of high quality integral-skin fine-celled foamed-core polyolefin moldings. The process innovatively conjoins the traditional rotational foam molding technology with extrusion melt compounding in a deliberate attempt to reduce the principal intrinsic disadvantages associated with rotational foam molding, i.e., the energy intensive and very lengthy processing cycles. A lab-scale custom-made heavy-duty experimental setup along with three mold shape variations (cylindrical, flat plate and container-like) have been designed and built. It was used for conducting a comparative experimental process validation by using all three mold designs for processing integral-skin foamed core polyethylene (PE) parts. The process control optimization included resin formulation optimization, direct foaming concept implementation for process simplification, and mold venting system re-design. The thereby modified process resulted in even shorter processing cycle times, lower energy consumption, and improved foam morphologies.
MORPHOLOGICAL AND MECHANICAL CHARACTERISTICS OF RIGID POLYURETHANE FOAMS
Nora Catalina Restrepo-Zapata , E. Alexander Ossa H. , Felipe Cano Mejia, May 2008
Cellular materials are formed by solid cells in a gaseous core. They exhibit good strength to mass ratio and they are used as insulators and as a core in sandwich composite manufacture. This work describes an extensive study on the structure and physical-mechanical properties of rigid polyurethane (PU) foams. The effect of composition and processing conditions on the mechanical properties were studied. Morphology specific strength and density were evaluated to determine the optimal levels of processing for a required application. Foam morphology was characterized using stereoscopy and optical microscopy. A basic mechanical property as compression strength was measured in the plateau zone.
MORPHOLOGICAL AND MECHANICAL CHARACTERISTICS OF RIGID POLYURETHANE FOAMS
Nora Catalina Restrepo-Zapata , E. Alexander Ossa H. , Felipe Cano Mejia, May 2008
Cellular materials are formed by solid cells in a gaseous core. They exhibit good strength to mass ratio and they are used as insulators and as a core in sandwich composite manufacture. This work describes an extensive study on the structure and physical-mechanical properties of rigid polyurethane (PU) foams. The effect of composition and processing conditions on the mechanical properties were studied. Morphology, specific strength and density were evaluated to determine the optimal levels of processing for a required application. Foam morphology was characterized using stereoscopy and optical microscopy. A basic mechanical property as compression strength was measured in the plateau zone.
NOVEL NANOBIOCOMPOSITES WITH ANTIMICROBIAL AND BARRIER PROPERTIES OF INTEREST IN ACTIVE PACKAGING APPLICATIONS
M.D. Sanchez-Garcia , E. Gimenez , M.J. Ocio , J.M. Lagaron, May 2008
It is well-known that the nanocomposites technology can significantly enhance among others the thermal mechanical and barrier properties of plastics. It is also known that most bioplastics including the thermoplastic biopolymers have lower than desired levels for certain properties which makes their use in certain packaging applications problematic. The combination of active technologies such as antimicrobials and nanotechnologies such as nanocomposites can synergistically lead to bioplastic formulations with balanced properties and functionalities for their implementation in packaging applications. The present work presents the development and characterization of novel nanocomposites of polycaprolactone (PCL) with enhanced barrier properties and with controlled-release of biocide natural extracts.The antimicrobial nanocomposites of biodegradable materials were prepared in solution by a casting method.The morphology of the biocomposites was visualized by transmission electron microscopy (TEM) and by Atomic Force microscopy (AFM) the thermal properties were investigated by differential scanning calorimetry (DSC) and the solubility and kinetics of released biocide were determined by Attenuated Total Reflection Fourier Transformed Infrared (ATR-FTIR) spectroscopy. Water and limonene barrier properties were also enhanced in the biocomposites.
A STUDY ON THE BLENDS OF HDPE AND LLDPE FOR ROTOMOLDING APPLICATIONS
Alexandra Fabre, May 2008
This paper examines the technical feasibility of using blends of high-density polyethylene (HDPE) with linear-low density polyethylene (LLDPE) for rotational molded underground water tanks application. Various blending ratios were investigated to determine the most optimum stiffness reasonable toughness and low warpage properties required in underground water tanks. Mechanical properties were characterized and determination of miscibility by different methods including zero shear viscosity study DSC analysis and Crystallization rate measurement were done in order to find the suitable ratio of blending. Rotomoldability was checked for this ratio to using vacuum tests. It was found that HDPE/LLDPE blends are miscible in all compositions and that the ratio 70:30 (HDPE:LLDPE) has the most optimum mechanical properties for underground water tanks and also for any load-bearing applications. The resulting warpage after vacuum tests confirmed mechanical characterization. The grade 70:30 with LLDPE MI 1 (g/10 min) can be used for underground water tank applications to increase mechanical properties and to reduce warpage.
HHEATING AND COOLING TECHNOLOGIES FOR INJECTION MOLDING TO IMPROVE PRODUCTS QUALITY
Hai-mei Li , Chang-yu Shen , Shia-chung Chen , Ho- hsiang Wang , Xin Wang, May 2008
Temperature is one of the most important processing parameters in injection molding which has effects on products quality and production efficiency. The relatively assistant heating and cooling technologies to adjust mold and resin temperature during the injection molding processing were discussed including heated water electric heater induction heating and chill water. Firstly the heating/cooling effects on the uniformity of mold temperature field and the time consumption to obtain the ideal processing temperature were considered by experiments. Then the appearance quality of molded parts (surface roughness) produced by the heating/cooling technologies were measured. The residual stress distribution of transparent PC parts made by different cooling rate was examined by photoelastic instruments.Compared with traditional processing it is found that microcellular injection molded specimens average surfaceroughness was reduced from 26 ??m to minimum 5.1 ??mwhen mold temperature above 18  ?? oC ?? From a series ofmulticolored band or fringe pattern it shows that whenmold temperature increase 20 oC ?? ?? ??he stress strip reducedfrom 6 to 2 which meant less residual stress.
HEATING AND COOLING TECHNOLOGIES FOR INJECTION MOLDING TO IMPROVE PRODUCTS QUALITY
Hai-mei Li , Chang-yu Shen , Shia-chung Chen , Ho- hsiang Wang , Xin Wang, May 2008
Temperature is one of the most important processing parameters in injection molding which has effects on products quality and production efficiency. The relatively assistant heating and cooling technologies to adjust mold and resin temperature during the injection molding processing were discussed, including heated water, electric heater, induction heating and chill water. Firstly, the heating/cooling effects on the uniformity of mold temperature field and the time consumption to obtain the ideal processing temperature were considered by experiments. Then the appearance quality of molded parts (surface roughness) produced by the heating/cooling technologies were measured. The residual stress distribution of transparent PC parts made by different cooling rate was examined by photoelastic instruments. Compared with traditional processing, it is found that microcellular injection molded specimens average surface roughness was reduced from 26?m to minimum 5.1?m when mold temperature above 18? oC? From a series of multicolored band or fringe pattern, it shows that when mold temperature increase 20 oC???he stress strip reduced from 6 to 2, which meant less residual stress.
SOLID STATE SHEAR PULVERIZATION AND CHEMICAL RECYCLING OF POLYMERS
Hossein Hosseini , Mohammad Mosaddegh , Behzad Shirkavand-Hadavand, May 2008
Solid state shear pulverization is a novel technology in polymer processing for production of new polymeric materials. By implementation of this technology various processes such as polymer recycling compounding and improving of mechanical-chemical properties of polymers can be enhanced. This is a continuous and one-stage process with low energy consumption. During this process polymers are subject to high pressure and shear forces. In this paper this technology and its applications to polymer processing is perused. At the end recycling of PET wastes by this technology is presented that have higher efficiency in comparison with existing methods.
SOFT THERMOPLASTIC POLYURETHANES
Donald Meltzer, May 2008
The synthesis and physical properties of soft plasticizer-free thermoplastic polyurethanes (TPUs ) exhibiting durometers below 70A on the Shore scale have been investigated. The TPUs have been further characterized in terms of their thermal and tensile characteristics set and tear properties as well as density. By employing hydrocarbon polyols along with suitable chain extenders aromatic TPU with specific gravity less than 1.0 that exhibit acceptable physical properties and exhibit low compression set characteristics have been prepared. Furthermore these TPUs are hydrophobic an unusual characteristic for a TPU which suggests that they could be useful for applications where TPUs would not normally be considered e.g. water barriers.
SOFT THERMOPLASTIC POLYURETHANES
Donald Meltzer, May 2008
The synthesis and physical properties of soft plasticizer-free thermoplastic polyurethanes (TPUs ) exhibiting durometers below 70A on the Shore scale have been investigated. The TPUs have been further characterized in terms of their thermal and tensile characteristics, set and tear properties as well as density. By employing hydrocarbon polyols along with suitable chain extenders, aromatic TPU with specific gravity less than 1.0, that exhibit acceptable physical properties and exhibit low compression set characteristics, have been prepared. Furthermore, these TPUs are hydrophobic, an unusual characteristic for a TPU, which suggests that they could be useful for applications where TPUs would not normally be considered, e.g., water barriers.
EVALUATION OF MULTI-SAMPLE MICRO-CAPILLARY RHEOMETER
Doyoung Moon , Anthony J. Bur , Kalman B. Migler, May 2008
We present a Multi-sample Micro-capillary Rheometer (MMR) which is capable of measurements over a broad range of temperatures viscosities and shear rates. The instrument is simple as the flow is generated by external gas pressure and the shear rate is measured optically. We test the MMR against two National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) three low viscosity standards and one commercial polymer (Polydimethlysiloxane Polyisobutylene solution Oils and Polystyrene) and report a high level of accuracy and precision. This instrument will be particularly useful as a combinatorial method and in cases of limited material quantity (typical sample size 20 ?¬L). The dynamic range of the instrument is eightorders of magnitude in viscosity and four orders of magnitude in shear rate.
IMPROVED PROPERTIES AND COST EFFICIENCIES OF CYCLIC OLEFIN COPOLYMER ENHANCED FORMING FILMS
Paul D. Tatarka, May 2008
Cyclic olefin copolymers (COC) can provide film producers and packaging converters with an opportunity to create thermoforming films. COCs are amorphous thermoplastics with excellent moisture barrier high temperature stability and stiffness. Mono- and multi-layer examples of LLDPE-based forming films compared against commercially available products clearly demonstrate how well the addition of COC improves physical properties thermoforming and packaging performance. COC improves material distribution of LLDPE formed trays. These improvements enable the formed tray to withstand higher crushing force. Enhanced performance permits possibility of down gauging.
APPLICATION OF THE HAMMETT ACIDITY FUNCTION FOR THE EVALUATION OF RESINS RESISTANCE
Valery G. Makarov , Rakhil M. Sinelnikova , Pavel V. Glukhovskiy, May 2008
Chemical resistance of resins determines the lifetime of plastic materials. Chemically stable resins with ester groups undergo the hydrolysis in acidic environment.This hydrolysis is catalyzed by hydronium ions.The Hammett acidity function determines the concentration of hydronium ions in concentrated acids and their mixtures.This function can be used for material evaluations in laboratory testing and specific industrial environments.We used this approach to evaluate the chemical resistance of Dion 9100 (epoxyvinylester based resin) and Polilate 250 (unsaturated isophtalicpolyester based resin).
ADVANCED COMPATIBILITY MATRICES BY MULTI-COMPONENT INJECTION MOLDING PROCESS
M. Schuck , I. Kühnert , E. Schmachtenberg, May 2008
The principles of materials compatibility for joining of plastics using multi-component injection molding have been investigated. In order to expand compatibility matrices the influence of processing transient and pretreatment parameters on the bonding strength has been identified. The Experimental approach has included the determination of the influences of in-line-plasmapretreatment melt temperature on the contact zone and the surface contamination. Electron spectroscopy surface tension electron microscopy and IR-temperaturemeasurements have been used to analyze the contact surface.
SIMULATIONS AND EXPERIMENTAL STUDIES OF INTERFACE DISTRIBUTION AND BIRIFRINGENCE IN THE SEQUENTIAL CO-INJECTION MOLDING OF AMORPHOUS POLYMERS
N. H. Kim , A. I. Isayev, May 2008
2D numerical simulations of the interface distribution and flow birefringence for combinations of PS PC and PMMA in sequential co-injection molding of a centergated disk were performed. A hybrid control volume/finite element/finite different method with modeling based on nonlinear viscoelastic constitutive equation and stressoptical rule was used. Free quenching was performed and thermal birefringence was measured. Interface distribution and birefringence in moldings were measured. The thermal birefringence is added to the flow birefringence to obtain the birefringence. The simulation results for the interface distribution and birefringence qualitatively match with experimental results.
SIMULATIONS AND EXPERIMENTAL STUDIES OF INTERFACE DISTRIBUTION AND BIRIFRINGENCE IN THE SEQUENTIAL CO-INJECTION MOLDING OF AMORPHOUS POLYMERS
N. H. Kim , A. I. Isayev, May 2008
2D numerical simulations of the interface distributionand flow birefringence for combinations of PS, PC andPMMA in sequential co-injection molding of a centergateddisk were performed. A hybrid control volume/finiteelement/finite different method with modeling based onnonlinear viscoelastic constitutive equation and stressopticalrule was used. Free quenching was performed andthermal birefringence was measured. Interface distributionand birefringence in moldings were measured. Thethermal birefringence is added to the flow birefringence toobtain the birefringence. The simulation results for theinterface distribution and birefringence qualitatively matchwith experimental results.
OPPORTUNITIES FOR PLASTICS MATERIALS AND PROCESSES FOR UNDER-THE-HOOD APPLICATIONS
Dr. Suresh Shah, May 2008
There is an increasing demand for light weight low system/part cost high fuel efficiency recyclability low manufacturing cost and freedom of parts consolidation for under the hood parts.This presentation will discuss state of the art for several key applications such as HVAC components radiator components fan-shroud assemblies/modules air intake manifolds engine (or ƒ??beautyƒ?) covers rocker panels and other multi-functional assemblies etc.Plastics have made significant inroads in valve covers and air-intake manifolds. In valve covers (also called rocker or cam covers) thermoplastics are replacing thermosets. Advances in thermoset materials will also be discussed. The reason for using other technologies other than conventional injection molding such as thermoforming blow molding water/gas injection molding etc. will be discussed for above mentioned applications. For example future air-intake manifolds may utilize laser welding to join two shell halves with less potential damage to sensitive electronics than with vibration welding.To reduce part weight technologies like thin wall molding microcellular foaming and nanocomposite molding will be discussed. There is a need for high flow materials with high temperature capabilities.Opportunities for several material families such as polyamide Polyolefinic materials PPS PPA etc are discussed. Integration need such as fan/shroud with partial or full front end module instrument module with HVAC integration cam cover with gasket and oil/air separator into one lower-cost module; air-intake manifold and rocker panel into a single multi-functional assembly. etc; will be briefly discussed.
DEVELOPMENT OF A PRESSURE DRIVEN MICRO-RHEOMETER
Younggon Son, May 2008
A pressure driven micro-rheometer was developed. It uses 80 mg of material to measure the viscosity of polymer melts at shear rates ranging from ten to several thousands s-1. The maximum shear rate can be extended to several 104 s-1 with 200 mg of sample. The main part of the rheometer consists of two sample reservoirs connected through a slit channel (H = 0.1 mm W = 1 mm L=5 mm) and two pistons. The double piston arrangement enables using the same material repeatedly by the reciprocating flow of the polymer melt from one reservoir to the other.In addition by using a very thin slit channel the viscosity of polymer melts can be measured over a wide range of shear rates whilst using only a small quantity of material.Measured viscosity was in good agreement with that by a capillary rheometer and it was found that slip is negligible in the slit die used in this study.


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