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 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.
Heat Transfer in Extruder Screws
Stephen J. Derezinski, May 2000
In the study and modeling of the resin temperature in extruder channels, the screw is commonly assumed adiabatic. However, the resin begins as a cold solid and is melted and heated as it flows, which requires that the screw also be cold at the entrance and hot at the exit. Heat must, therefore, be conducted in the screw metal from the hot end of the screw to the cold end, which requires heat transfer with the melt. Also, the heat capacity, especially of larger extruders, can require significant time to attain steady-state operation. A model of transient heat conduction in the screw coupled to heat transfer with the resin feed, melting, and pumping is used to investigate these two phenomena.
Electrospun Nanofibers of Electronic and Photonic Polymer Systems
C. Drew, X. Wang, K. Senecal, H. Schreuder-Gibson, J. He, S. Tripathy, L. Samuelson, May 2000
Electrospinning employs strong electric fields to create nanometer scale fibers. The fibers are collected as a non-woven fiber membrane with a very large surface area to volume ratio. Sulfonated polystyrene, enzymatically synthesized polyaniline and blends thereof, and dye-sensitized composite polymeric systems were electrospun and studied to optimize fiber formation. It is expected that these types of electrospun materials will find potential use as new lightweight electronic and photonic materials in numerous device applications.
A Fast Approach to Automotic Runner Balance
Kun-Chih Chen, Rong-Yeu Chang, David C. Hsu, Alice S. Lin, Kelly Lu, May 2000
Runner balance is one of the most important issues to be addressed for multi-cavity mold in the mold design phase. Poor runner sizing will lead to Christmas tree filling pattern and hence different residence time of plastic melt on each cavity. This leads to excessive packing pressure on small cavity and part weight variation. This problem becomes more crucial for the so-called family mold. In this work, the concept of flow balance index (FBI) is proposed to address this problem. Real industrial cases are studied by this new approach and are verified by molding trial results.
CAE Approach to Relieve Notebook Connector Air-Trap Problems
Rong-Yeu Chang, Alice S. Lin, David C. Hsu, Fu-Ming Hsu, May 2000
Air trap problem is crucial to notebook connectors that have complicated rib-hole structure and thickness variation. Engineering experience is usually not enough to provide a suitable gate-runner system design for these intricate parts. In this work, various design proposals are examined via mold filling simulation in order to avoid potential air-trap and void problems. This approach is proved to be effective to notebook connector mold designer for verifying design on computer before mold is constructed.
Preventing Sink Marks of Injection Molded Parts Using CAE Analysis
Shijun Ni, May 2000
Sink marks on injection molded parts were caused mainly by part geometric design, mold design, and molding process conditions. This paper describes the dominant factors causing sink marks on injection molded part that can be predicted using CAE injection molding simulation programs. Sink marks on injection molded parts should be prevented for a new part design or solved for an existing one based on simulation results. In this study, a Bearing Bur, Laser printer part was chosen to illustrate how sink mark problems were solved using a commercial available C-MOLD® simulation program. The predicted sink marks of the Bearing Bur were compared to the measurements of an actual production part. Predictions were in good agreement with the actual injection molded part.
Apparent Viscosity Measurements for Determining Injection Molding Dimensional Variations
Gary L. Freiberg, May 2000
Injection molders presently use the Apparent Viscosity Curve" to determine the optimum fill time for a particular mold. Once the fill time has been determined the Viscosity Curve is set aside and the goal of the molder is to maintain the fill time. The motivation for my work is not only to determine fill time but also to quantify the melt viscosity using an injection molding machine/mold combination. The ability to determine the melt viscosity would assist the molder with "root cause" analysis when evaluating small dimensional shifts. The study will focus on determining if the derived viscosity using traditional rheological equations is of value when compared to dimensional or cosmetic changes."
A Transparent Barrel for Study of Reciprocating Screw Injection Molding
Furong Gao, Zhiming Jin, Xi Chen, May 2000
A transparent barrel system has been developed to assist in the understanding of polymer behavior in a reciprocating screw injection molding machine. This system allows the dynamic status of the polymer inside the injection barrel to be conveniently visualized though photography and video recording, and the corresponding material conditions can be measured via a computerized data acquisition system. Effects of different processing conditions on the melting behavior are analyzed. This system can not only assist in the understanding of the process but also can be used to quantitatively verify the modeling and optimization of injection molding system.
Characterization of Biaxial Orientation in Polyolefin Films
A. Ajj, K.C. Cole, May 2000
Among the most widely used orientation processes are those involving films; they include both film blowing (with a low level of orientation) and biaxial orientation or tentering (with a high level of orientation). Polyolefins (polyethylene, polypropylene, polystyrene, and their copolymers) represent a significant proportion of the polymers commonly used in these processes. The knowledge of the orientation developed in these films is critical for establishing the process conditions and the final properties of the films. In this study, we investigate the biaxial orientation developed in blown and biaxially oriented polyethylene films using Fourier transform infrared (FTIR) spectroscopy and birefringence. Biaxial orientation factors are determined for both crystalline and amorphous phases and discussed in relation with process conditions.
Measuring the Low Frequency Linear Viscoelastic Properties of Polymer Melts: Trials with PDMS Using Sphere-Plane Squeeze Flow and Interferometry
Edwin C. Cua, Montgomery T. Shaw, May 2000
The problem of measuring the linear viscoelastic (LVE) properties of polymers at low frequencies is a long-standing one, especially for polyolefins with broad relaxation times and small time-temperature shift factors. A squeeze flow apparatus utilizing Newton's interference rings has been devised to measure minute strains at very low stresses with a minimum resolution of ¼ wavelength of light. Its simplicity allows several samples to be run simultaneously under vacuum. This arrangment minimizes degradation, manhours and cost, all critical considerations for long experiments. The design and preliminary results for PDMS as measured by a prototype of the instrument will be discussed.
New Polypropylene for Differentiated Blown Films
W.D. Hoenig, C.P. Bosnyak, K. Sehanobish, W. Van Volkenburgh, C. Ruiz, L..M. Tau, May 2000
New polypropylene resins have been developed which allow for the commercialization of novel, air-quenched blown films. The new resins have been developed using molecular design principles and provide significantly enhanced properties. Key performance properties include stiffness, seal strength, and higher service temperature for many applications as well as flexibility and toughness for other applications. This new breadth in product offerings and performance ranges provides significant new opportunities for PP resins in blown films. This paper will highlight properties and processability of the new resins.
Improvement of Pentium-II Connector Support Design by CAE Tool
Thomas Hsieh, David C. Hsu, Alice S. Lin, Andy G. Day, Rong-Yeu Chang, May 2000
Weld line problem is crucial to a Pentium-II connector support part on appearance and mechanical consideration. In this work, a CAE tool is adopted during the product-development in order to detect potential weld line problem of the design. Various design revisions are proposed and tried on the computer. This approach is proved to be cost-and-time-effective to shorten time-to-marketing and avoid molding problem by improving design in advance.
In-Situ Production of Electrically Conductive Fibres in Polyaniline-SBS Blends
R.H. Cruz-Estrada, M.J. Folkes, May 2000
Electrically conductive polyaniline (PANI) was thermally blended with polystyrene-polybutadiene-polystyrene (SBS) at different weight compositions. The resultant blends were capillary extruded in order to generate a drawing process in the PANI. Microscopic analysis of the extrudates revealed that the PANI was deformed during the process to produce elongated structures. Electrical measurements showed the relationship between the electrical conductivity and the weight fraction of PANI in the blends.
Novel Fiber Surface Treatment for Use in Engineering Thermoplastic Composites
Jianwei Xu, Lawrence Acquarulo, Charles O'Neil, May 2000
A water-soluble polymer (Polyoxazoline) was used to treat nickel coated graphite (NCG) fiber and the treated fiber was then used to reinforce ABS, Polycarbonate and Polyetherimide. The water-soluble polymer improves the compatibility of the fiber in the thermoplastic resin matrix thereby providing an improved thermoplastic composite material with optimum mechanical and electrical performance.
Physical Model of Polymer Pellets Melting in Co-Rotating Twin-Screw Extrusion
Zhu Linjie, Geng Xiaozheng, May 2000
The melting of polymer in co-rotating twin-screw extruder depends not only on screw configurations and operational conditions, but on the properties of the polymer as well. The melting progressing is too various to be described by single melting model. Only in the past few years (1-9), some attention has been paid to the research of polymer melting in co-rotating twin-screw extrusion. In present study, based on experimental results, the conception of melting sub-stage was defined to describe the complex polymer melting progressing in co-rotating twin-screw extrusion. Ten melting sub-stages were concluded and defined. It was found that the complicate polymer melting progressing can be modeled by combining some of these ten melting sub-stages. It showed that the definition of melting sub-stages would provide an important way to the research of polymer melting in twin-screw extrusion.
Numerical Analysis on the Melt Conveying Properties of Wave Screw Element in Intermeshing Counter Rotating Twin-Screw Extruder
Zhou Fuping, Geng Xiaozheng, May 2000
In this paper, one new kind screw element, wave screw element in intermeshing counter-rotating twin screw extruder, is designed. Three-dimensional Non-Newtonian model is established to investigate the melt conveying properties of this new screw elements. The model consists of all the gaps between the screws and the barrel such as the side gap, the calender gap, the flight gap, and the tetrahedron gap, which is in accordance with the true extrusion process. With the finite element software ANSYS, velocity, pressure and viscosity field are obtained respectively. Experiments are used to verify the results of simulation. It shows that the calculated results such as output is nearly the same as the experimental results.

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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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