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

Shrinking Control and Residual Styrene of Unsaturated Polyester Resins Cured at Low Temperatures

Xia Cao, L. James Lee, May 2002

In low temperature molding processes, shrinkage control and residual styrene are important concerns. The presence of low profile additives (LPA) can reduce the shrinkage of unsaturated polyester (UP)/styrene (St) resins cured at low temperatures under proper processing conditions. A systematic study was carried out to investigate the effect of reaction temperature, initiator systems, and modification of the resin system on structure evolution, final resin conversion, and shrinkage control of UP resins with LPA.

Simulation of Microcellular Foaming in Injection Molding

R. Zheng, P. Kennedy, J. Xu, L. Kishbaugh, May 2002

We present a simulation model for the MuCell® injection molding process in which supercritical fluid such as carbon dioxide or nitrogen is mixed with molten polymer and injected into the mold. The model accounts for the development of cells in the melt, their effect on viscosity and compressibility and the subsequent expansion of the melt to fill the cavity. Simulation results and their comparison with experiments will be discussed.

Sintering of Thermotropic Liquid Crystalline Polymers

Eric Scribben, Donald Baird, May 2002

Two thermotropic liquid crystalline polymers were evaluated for use in rotational molding: Vectra A 950 and Vectra B 950. Material is typically prepared by grinding. When ground, even under cryogenic conditions, TLCPs tend to yield particles of high aspect ratio translating to low bulk density, poor granular flow, and incomplete densification. A process was developed to generate spherical particles of controlled size and distribution. Particle coalescence and densification characteristics were determined and compared against model predictions.

Soft Contact Lenses: A Material Review

Annapoorna Rajan, Aldo Crugnola, May 2002

Soft contact lenses contribute up to 85% of the market for contact lenses in the U. S. The concept and the introduction of contact lenses, the history of the development of soft contact lenses and the materials currently used for contact lenses are discussed in this paper. The manufacturing method and the surface treatment are also briefly reviewed.

Solid-Bed Break-Up during Plastication in Injection Molding

Zhiming Jin, Furong Gao, May 2002

Uniformity in polymer melting in the screw-barrel system has very important influences on the quality of injection molded products. An experimental study on injection plastication is conducted with HDPE in a visual barrel system. Solid-bed break-up phenomenon is observed and analysed under different processing conditions.

Spotlight on Plastics Joining Advances at K 2001

C. Bonten, May 2002

A large number of improvements in plastics joining technology have been stimulated by the end user. The influence of the car industry's suppliers and the car industry itself, along with the telecommunications and construction industries and medical technology were reflected in recent developments that have been presented at the K-fare in Düsseldorf/Germany at the end of October 2001.

Stability of Two-Stage Single-Screw Extruders

Stephen J. Derezinski, May 2002

In two-stage extrusion, the pumping section must be sized to produce the needed delivery pressure of the extruder. A method of calculating the channel depth so that the desired pressure is achieved and that the stability of the flow is optimized has been developed. Data for an example are given.

Structure Development in Melt Spinning of Cyclopolyolefin Filaments

Myeong-Ho Hong, James L. White, May 2002

Melt spinning of cyclo-polyolefins is presented. The birefringences of the melt-spun filaments were determined and contrasted with spinline stress. These were found to be much lower than polycarbonate and polystyrene filaments melt spun under the same conditions. The birefringence was represented in terms of polymer chain orientation.

Structure of Nanocomposites Foams

Changchun Zeng, Xiangmin Han, L. James Lee, Kurt W. Koelling, David L. Tomasko, May 2002

Exfoliated and intercalated polymer/clay nanocomposites were synthesized and used to prepare nanocomposite foams, using CO2 as the foaming agent. The foam structure was observed by scanning electron microscopy (SEM), while transmission electron microscopy (TEM) was used to observe the detailed clay distribution. The effect of clay dispersion and clay concentration on the cell structure was investigated.

A Study of Degradation of LLDPE under Accelerated Conditions

Luis C. Mendes, Ana C.M. Costa, Ailton de S. Gomes, May 2002

In order to use linear low density polyethylene (LLDPE) as external duct lining of oil pipes, we have evaluated the aging of this polymer. The experiment has been carried out under accelerated UV fluorescent lamps exposure, during 336 hours.We focused our investigation on changes on mechanical properties occurring over the aging process.The LLDPE studied was mixed with peroxide in order to modify its properties.

Study of PVC Stabilization Using Capillary Rheometry

Radu Bacaloglu, Michael H. Fisch, Ulrich Stewen, Ilze Bacaloglu, Edward Krainer, May 2002

Capillary rheometry allows monitoring PVC thermal and shear stress degradations separately. Based on testing of PVC compounds with a capillary rheometer, stabilizers can be efficiently optimized to reduce both degradation processes. Capillary rheometry is an important tool to improve productivity of PVC processing further at high shear rates.

Study of the Effect of Velocity-to-Pressure Transfer Method on Process Robustness in the Injection Molding Process

Tiffany A. Beers, Nicholas Decker, May 2002

This study will compare the use of several different transfer modes during the filling phase of the injection molding process. These modes include screw position, hydraulic pressure, and melt pressures within the cavity and nozzle. The modes will be investigated by using cavity pressure consistency when regrind and check ring wear are introduced. There are 4 transducers located in different areas within the cavity that will measure the peak pressures.

Styrene Block Copolymer Modified Food Wrap Film

Catherine Maris, Michael Modic, May 2002

Stretch wrapping film has been used for over 30 years to protect and preserve food from moisture, dirt and abrasion. These films allow increased food shelf lives and give the package an appealing smooth and shiny appearance.Styrenic block copolymers can be blended with polypropylene and co-extruded with ethylene vinyl acetate to form multi-layer structures suitable for food wrap applications. These films offer an excellent balance of properties combined with a low density.

Taguchi Based Design of Experiments of HDPE and Granite Fines

Greg Kopple, Joseph Greene, May 2002

Granite-filled HDPE had lower tensile strength, modulus and elongation than unfilled HDPE. The reduction in properties is attributed to large particles that serves as stress concentrators. The mechanical properties of HDPE are improved with the use of adhesion promoters and use of metallic granite. A Taguchi design of experiment determined that the metallic component of the granite fines had higher tensile strength, modulus, hardness, and elongation at yield than the bulk granite fines.

Temperature Sensitivity of the Linear Viscoelastic Properties of Long Chain Branched Metallocene Polyethylene

Paula Wood-Adams, Stephane Costeux, May 2002

The effects of long and short chain branching on the thermorheological behaviour of polyethylene are described. Long chain branched homo -polyethylene is thermorheologically complex and is most sensitive to temperature at low frequency. A technique for determining the activation energy spectra of thermorheologically complex materials is proposed. Short and long branches in the same system synergistically increase the zero-shear rate activation energy.

Tensile Properties of PE Clay Nanocomposites via Taguchi Based Design of Experiments

Joshua Miller, Joseph Greene, May 2002

LDPE and HDPE clay nanocomposites prepared with melt mixing demonstrate increased stiffness and strength with increasing concentrations of clay nanocomposites and adhesion promoters. Taguchi design of experiment (DOE) methodology determined the optimum material conditions to achieve maximum strength and stiffness. The nanocomposites increased tensile modulus and tensile strength, but reduced elongation of LDPE and HDPE. Maleic anhydride and acrylic acid improved the tangent modulus and ultimate tensile strength of polyethylene/clay nanocomposites.

Terpolymer Sequences and Geometric Distribution

Kal. Renganathan Sharma, May 2002

Chain sequence distribution calculations for terpolymers using probability model and Monte Carlo simulation methods are discussed. The SSS, AAA, SAS, SSA, ASA, AAS trial concentration are obtained. Molecular weight and ceiling temperature effects are studied using the Monte Carlo method.

Three-Dimensional Simulation of Thermoset Molding Applied to Semiconductor-Chip Encapsulation

Sejin Han, Franco Costa, Peter Cook, Shishir Ray, May 2002

In this paper, numerical methods to analyze the flow of thermoset materials during the molding process have been developed. A finite-element method is used for the three-dimensional flow analysis. The numerical analysis results have been verified by comparing with experiments. In the experiment, a semiconductor chip encapsulation process using a thermoset-molding compound has been used to observe the melt-front advancement shapes. The calculated and experimental results show good agreement.

Time-Resolved SAXS Studies on the Crystallization Behaviors of Poly(Ethylene Terephthalate) and its Copolymers

Byeongdu Lee, Tae Joo Shin, Seung Woo Lee, Moonhor Ree, May 2002

Using synchrotron radiation sources of Pohang Light Source, Pohang University of Science & Technology, Korea, small-angle X-ray scattering (SAXS) measurements have been carried out for poly(ethylene terephthalate) (PET) and poly(ethylene isophthalate-co-terephthalate) s which undergo isothermal crystallization and during subsequent re-melting. Differential scanning calorimetric (DSC) measurements were additionally conducted.

Transient Behavior of Extruders: Input Disturbances

Rajath Mudalamane, David Bigio, May 2002

A model of the transient response of an extruder to varying input feed rates and screw speed was developed and used to study the effect of input disturbances on the extrusion process. Simulated tests reveal that given a screw design, there is a critical frequency below which disturbances will not be damped significantly by the extruder. The relationship between screw geometry and this critical frequency is presented. The effect of specific throughput (Q/N) on damping ability of a screw geometry is also presented in this paper.