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
Simulation of Shearing and Mixing Sections
H. Potente, W. Többen, May 2000
Three-dimensional finite-element-calculations on spiral shear sections and faceted mixing sections have been applied to test the influence of geometry onto pressure-throughput and mixing performance. Well-chosen dimensionless numbers described the geometrie of the elements so a statement about the process development could be reached. Residence time and the Flow Number ? were utilized to evaluate the mixing effect and its information value.
Anisotropic Thermal Conduction in Deforming Polymer Melts
D.C. Venerus, J.D. Schieber, H. Iddir, J.D. Guzman, A.W. Broerman, May 2000
Energy transport in deforming polymeric materials, despite its technological significance, is poorly understood from both experimental and theoretical standpoints. Simple arguments suggest that thermal conductivity is anisotropic in a deformed polymer. In this study we have developed a sensitive and non-invasive optical technique known as Forced Rayleigh Scattering to measure anisotropic thermal diffusivity in both static and dynamic (relaxing) polymers subjected to deformations. Results for a polymer melt in step-shear strain flow and a cross-linked elastomer in uniaxial extension indicate that the thermal diffusivity is enhanced in the flow (or stretch) direction compared to the equilibrium value.
Evaluation of Thermoplastic Polyurethane Based Thermoplastic Vulcanizates for Interior Automotive Applications
Michihisa Tasaka, Naganori Masubuchi, May 2000
Although thermoplastic polyolefins (TPOs) have been considered as costwise and environmentally attractive materials, they face the difficulty in being used as potential automotive applications because of poor scratch resistance and oil resistance. The new thermoplastic vulcanizates (TPVs) composed of thermoplastic polyurethane (TPU) / polypropylene (PP) /polystyrene-block-poly(ethylene-co-propylene)- block-polystyrene copolymer (SEPS) systems have been found out to have outstanding oil resistance and scratch resistance. Now they can be used for various kinds of automotive applications such as injection molded, blow molded, extruded, calendered and further, slush molded automotive parts, particularly for automotive interior skins without any coat. The essential issue is conceivably just prolonged weathering resistance and durability. In this paper, this new TPVs are evaluated from the standpoints of weathering stability, long term heat aging and fogging as well as the mechanical and physical properties.
Study of the Characteristics of Thermoplastic Vulcanizates of PP/SEPS/SBS Blends
Michihisa Tasaka, Shinzo Saito, May 2000
Thermoplastic vulcanizates (TPVs) of polypropylene (PP)/polystyrene-block-poly(ethylene-co-propylene)- block-polystyrene copolymer (SEPS) are able to become much more fascinating for automotive and architecture industry by using polystyrene-polybutylene-polystyrene copolymer (SBS) together. While SBS decreases tensile strength in these systems , it does improve compression set and oil resistance greatly and furthermore, overall balance of properties improve in proportion to the amount of peroxide as coupling agent and acrylic ester as coupling coagent. The goal of this study is to investigate the interaction between SEPS and SBS, which are dynamically crosslinked and microdispersed in PP matrix from the point of mechanical behavior and morphology.
Characterization of Dual Crystalline Texture and Process-Structure-Property Relationships in HDPE Blown Films
Jianjun Lu, Hung-Jue Sue, Thomas Rieker, May 2000
The crystalline texture in selected high-density polyethylene (HDPE) blown films was studied using transmission electron microscopy, small-angle X-ray scattering and infrared dichroism. An orthogonally oriented dual crystalline texture was found. This structure appears to consist of two superimposed uniaxial crystalline textures. In one texture the lamellae are stacked along the machine direction, while in the other, the lamellae are stacked along the transverse direction. The lamellar populations in the two textures are affected greatly by the neck height of the film blowing process. The mechanical properties of the HDPE films can be well correlated with the dual crystalline texture observed.
Relationship between Local Residence Time and Distributive Mixing in Sections of a Twin Screw Extruder
Gifford Shearer, Costas Tzoganakis, May 2000
Local residence time and distributive mixing were measured in conveying sections and kneading blocks of a twin screw extruder. The residence time measurements were completed using carbon black as the tracer and an infrared temperature probe to detect the temperature decrease caused by the changing surface emissivity. A mixing limited interfacial reaction between polymer tracers was used to directly measure the distributive mixing. Possible relationships between mixing and residence time in the sections of the twin screw extruder were investigated by combining these two measurements.
Tooling Project Management of Injection Molding
Michael Yue, May 2000
Delivering good qualify mold on time is always a big issue for both mold maker and molder. Either of them could loss business if the tool is delayed and or in poor quality. How to avoid these? This paper starts with tooling flow chart and discusses tooling project management techniques. The problems encountered in tooling scheduling and manufacturing process are analyzed. Also, tooling qualification and cost reduction are discussed.
An Assessment of Weld Heterogeneities in PMMA Using Birefringence
R.J. Wise, R. Thomas, May 2000
This paper concentrates on the measurement of melt orientation of polymer chains and welding residual stress using birefringence. PMMA specimens were welded using four techniques, hot plate welding, laser welding, hot gas welding and ultrasonic welding. Measurements of birefringence made in transverse sections showed that levels of polymer chain orientation and some components of residual stress could be measured. These measurements were used as a basis for the assessment of heterogeneities introduced into PMMA during welding by the four techniques.
Foaming of Thermoplastic Elastomers with Water
Abdelhadi Sahnoune, May 2000
We present results on foaming of a thermoplastic elastomer (TPE) using water as the physical blowing agent. The TPE is a blend of polypropylene and fully crosslinked EPDM rubber made by a dynamic vulcanization process. The influence of the blowing agent content, and the processing conditions on foam density, cell nucleation, and foam structure are discussed. A brief discussion about the similarities and the differences between foaming in homopolymers and in TPEs is also included.
Evaluation of Layer Spreading in Coextruded Structures via a Modular Die
Joseph Powers, Joseph Dooley, Carl Reinhardt, Gary Oliver, May 2000
Layer spreading in coextruded sheet structures remains a problem solved more often with art than with science. A modular die, i.e. a die with inserts for the entrance channel and for the manifold, was designed and evaluated for a range of entrance shapes, manifold shapes, and resins. The results from these experiments lead to an improved selection process for die designs for coextruded sheet.
Rheology and Degradation Kinetics of Poly(ethylene terephthalate)/Poly(ethylene naphthalate) Blends
S.R. Tharmapuram, S.A. Jabarin, May 2000
Blends and copolyesters of poly(ethylene terephthalate)/poly(ethylene naphthalate), PET/PEN, have shown promise in high performance container applications. Both rheology and degradation kinetics of these blends have been studied as a function of material composition. Melt viscosity loss was measured as a function of time and temperature. Activation energies for degradation were calculated from experimental data. Results show that blends containing a minimum of 10% PEN by weight are as stable as PEN. Addition of low amounts of PEN to PET causes a depression in melt viscosity. A critical composition of 10% PEN by weight is required before we observe an increase in blend viscosity.
The Heating/Melting Mechanism of Plastic Energy Dissipation
Myung Ho Kim, Costas G. Gogos, May 2000
The Paper discusses the bulkwise heat source melting mechanism, we have termed Plastic Energy Dissipation (PED). When solid particulates are deformed in the melting section of polymer processing equipment, where melting occurs in a dissipative mix melting mode, part of the applied mechanical energy to deform solid particulates dissipates into heat. The amount of heat dissipation is quite large for both amorphous and semicrystalline polymers. A number of PED experiments were conducted as functions of strain rate, strain and temperature and the iso-temperature rise plots were obtained in temperature-strain space for commercial amorphous and semicrystalline polymers. A method to estimate melting length for Co-TSE was also developed.
Transesterification Reaction Kinetics of Blends of Poly(ethylene terephthalate) and Poly(ethylene naphthalate)
S.R. Tharmapuram, S.A. Jabarin, May 2000
Blends of poly(ethylene terephthalate)/poly(ethylene naphthalate), PET/PEN, have exhibited properties that are of commercial interest to the packaging industry. Melt processing of PET with PEN results in transesterification reactions. The blend properties are controlled by the kinetics of these reactions and these have been widely studied. Modifications to the chemical kinetic equations have been made to predict a theoretical processing temperature for different compositions of the blends to achieve critical transesterification. These values were found to be in close agreement with the experimentally observed values when blends were processed in a twin screw extruder.
The Influence of Morphology on the Impact Performance of an Impact Modified PP/PS Alloy
S.P. Bistany, May 2000
Brittle impact failures were observed at low temperature on blow molded parts made from a PP/PS alloy that is normally ductile for injection molded parts tested at same temperature. An investigation was launched to determine the cause of these failures. SEM analysis on the inside surface of the blowmolded part revealed the presence of micro-voids and large spherulites. Additionally, cross-sectional analysis of the inside surface showed coalescence of the impact modifier. These factors are believed to have contributed to the brittle failures. A test method was developed in an attempt to confirm these findings.
Shrinkage Behavior of Oriented Poly(ethylene terephthalate)
R. Mody, E.A. Lofgren, S.A. Jabarin, May 2000
The kinetics of thermal shrinkage of poly(ethylene terephthalate) films have been characterized and related to various parameters of the stretching process. Amorphous orientation functions and levels of crystallinity have been found to be of major importance to the shrinkage process. As film extension ratios increase, shrinkage behavior passes through five different regions. Shrinkage first increases with extension ratio, decreases with further extension to reach a minimum, and then increases again as extension is continued to higher levels. A schematic model has been proposed to describe molecular changes in polymer chain structures, within each of the shrinkage regions. Activation energies of shrinkage have been determined in addition to equilibrium shrinkage and shrinkage rate constants.
Filament Winding of Bicomponent Fibers Consisting of Polypropylene and a Liquid Crystalline Polymer
Jianhua Huang, Priya Rangarajan, Jay Sayre, Alfred C. Loos, Donald G. Baird, May 2000
Bicomponent fibers consisting of a sheath of polypropylene (PP) and a core of thermotropic liquid crystalline polymer (TLCP) were used in filament winding to form tubes suitable for transporting liquid oxygen. As the first step, the TLCP/PP bicomponent fiber was spun and the mechanical properties of the fibers were determined as a function of temperature to establish the conditions suitable for filament winding. Under these conditions the tensile modulus and strength of the filaments can be maintained in the filament wound products.
An Experimental Investigation of the Effect of Polymer Processing Additives (PPA) on the Melting and Gel Formation Mechanisms in a Single Screw Extruder
K.R. Slusarz, J.P. Christiano, Stephen E. Amos, May 2000
Much work has been published showing how the addition of a polymer processing aid (PPA) has improved the processing characteristics on the single screw extruder. This paper will give insight on how the PPA affects a single screw extruder. Solids conveying, melting, and melt conveying were experimentally studied to determine how the PPA affected these important processes during extrusion leading to improvements in the melt quality.
Effects of Varying Strand Length on Shielding Properties of Conductive Elastomers in Near-and Far-Field Experiments
Douglas Luther, May 2000
A new study examined the effects of varying the strand length of extruded conductive thermoplastic elastomer (TPE) pellets on the shielding efficacy of plaques molded of the material in both near- and far-field experiments. Results indicated that longer strand lengths yielded parts with higher shielding efficacy but at a cost of higher durometer and modulus. Data also indicated that far-field results were consistently higher than near-field values for the same materials and frequencies.
Measuring Frosted Glass Effects for Plastics: A Closer Look at One Frosting Agent
Tracy Phillips, May 2000
To produce consistent frosted plastic effects it is necessary to measure basic performance characteristics of the frosting agents. Frosted plastic, like frosted glass, serves a variety of aesthetic and functional needs. In testing, the most crucial characteristics are transmittance, haze, clarity and yellowness This paper examines two sets of data: 1. Comparative results of testing a series of frosting agents at differing loads 2. Specific, in-depth results of testing a single frosting agent at differing particle sizes.
Dependence of Draw Resonance on Extensional Rheological Properties of LLDPE
Michael J. Bortner, Donald G. Baird, May 2000
The effect of extensional rheology on draw resonance during fiber melt spinning is studied. Two linear low-density polyethylenes(PE's) synthesized using metallocene catalysts are compared. The LLDPE's appear to have different amounts of long chain branching, resulting in differences in extensional rheology. However, both materials behave almost identically in shear. During melt spinning, the PE's exhibit different critical draw ratios at which the onset of draw resonance occurs. Furthermore, the period of resonance changes with increasing draw down ratio for both PE's.
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