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
Estimation of Elongational Viscosity of Polymers for Accurate Prediction of Juncture Losses in Injection Molding
Mahesh Gupta, May 2001
A new elongational viscosity model along with the Carreau model for shear viscosity is used for a finite element simulation of the flow in a capillary rheometer. The entrance pressure loss predicted by the finite element flow simulation is matched with the corresponding experimental data to predict the parameters in the new elongational viscosity model.
Measurement of Strain Rate-Dependent Material Properties for Polymers
M. Keuerleber, P. Eyerer, J. Bühring, May 2001
Present market forces dictates that the automotive industry must increase passengers safety. Currently, CAE-Methods such as crash-simulations are used, but due to the absence of material data of polymers at high strain rates, the results of these simulations are in general inaccurate. This study is concerned with material testing on airbag cover materials with a high speed tensile testing machine to provide material data and information on material behaviour at different strain rates and temperatures.
Large Part Injection Molding Product Optimization
T.J. Schwab, D.L. Wise, J.D. Goudelock, B.J. Hughes, May 2001
High-density polyethylene (HDPE) is widely used in large-part injection molding applications, such as five-gallon pails, agricultural bins, and refuse carts. Certain physical properties are critical in helping to ensure a long useful life for parts in these demanding applications. This paper presents a predictive model that was developed from molded part testing and HDPE resin physical properties. By implementing this information effectively, the resin producer and the injection molder can work together to improve molded part performance.
Blow Molding Virgin and Regrind Polymers with Titanates and Zirconates - 2001
Salvatore J. Monte, May 2001
In addition to filler/pigment to polymer coupling, two parts of neoalkoxy titanates and zirconates per thousand parts of polymer provide for in situ metallocene-like Repolymerization" catalysis of the filled or unfilled polymer during the plastication phase resulting in: faster blow molding production cycles at lower temperatures; maintenance or increase in mechanical properties; the in situ regeneration of regrind polymer properties; the lowering of polymer recrystallization time; and the copolymerization of dissimilar polymers."
Morphology of PCL/EVA/PET Ternary System
Luis C. Mendes, Beatriz S. Chagas, Anderson R. dos Santos, May 2001
The morphology of ternary blends of polycaprolactone (PCL) / ethylene-co-vinyl acetate) (EVA) / poly(ethylene terephtalate) (PET) was investigated using optical microscopy. The sample appears as an aggregate mass. After controlled heating (30 to 280°C) it was noticed that the system forms an immiscilble blend where each component had its own melting temperarture. It was observed that the PCL was the major component and EVA was the minor one. The EVA domain did not present birefrigence. The PET domain was hidden by PCL and EVA.
Novel Nanoporous Polymers for Low-k Dielectrics
S.L. Simon, J. Sun, P. Doshi, B. Lahlouh, X. Chen, S. Gangopadhyay, May 2001
We are investigating new routes to making low-k dielectric films for use in next generation interconnects. Plasma enhanced chemical vapor deposition of conventional and novel monomeric precursors is used to deposit the films. Supercritical carbon dioxide processing is used to produce nanopores. The physical and electrical properties of the films are characterized.
Optimization of Process Parameters in Curing of Epoxy Resin Using Argon-Ion Laser
K.A. Jagadeesh, M. Sivakumar, Yamanoor Srihari, May 2001
Stereolithography, is used for prototyping and regular production for critical applications. It is necessary to optimize the process to ensure highest quality of products. Surface finish is the quality characteristic chosen and four the process parameters, namely, scanning velocity, laser power, hatch spacing, and layer thickness. Taguchi's method has been employed to find out the relative contribution of the factors to the surface finish and based on the experiments, the optimal values have been established.
Die Swell Estimation for HDPE Blow Molding Grade Resins Using the Wagner Model Constitutive Equation
Jaime Bonilla Ríos, Juan José Aguirre, May 2001
A polymer flow analysis inside a concentric annular die of an extrusion blow-molding machine was conducted using momentum and continuity balances coupled with the Wagner rheological constitutive equation for six high density polyethylene (HDPE) resins and then used to determine the thickness swell. The rheological measurements included oscillatory behavior, relaxation modulus, steady state behavior, and capillary flow.
Polyethylene Powder Characteristics: Impact on Polymer Sintering and Rotational Molding
S.A. Guillén-Castellanos, C.T. Bellehumeur, M. Weber, May 2001
The effect of powder characteristics on the rotational molding and sintering performance was investigated. The six LLDPE resins showed comparable rheological and thermal properties. Resins with poor powder quality produced parts with lower density and impact strength. The irregularities in shape due to grinding influenced the sintering results. To eliminate this effect on the sintering experiments cylinders were used. Variations in the sintering results, however, were also observed when using cylinders.
CD Case Design Using a Simulation Software for Injection Molding Processing
R.A. Morales, A.M. Marin, J.L. Carao, A.M. Alvizu, May 2001
The objective of this work was to design an injection mold for a CD case. A commercial case design has been analyzed and led to the proposal of a new one. The study was made using the mold filling/cooling simulation program for the injection process, and a three-dimension solid modeler program for planes accomplishment. The results showed that the actual design presented stress concentration in specific areas of the part. A new case design was proposed with optimized performance and with enhanced final part quality.
Non-Isothermal Melt Densification in Rotational Molding
J.S. Tiang, C.T. Bellehumeur, May 2001
The numerical simulation of the non-isothermal melt densification in the rotational molding process is presented. The simulation combines heat transfer, polymer sintering and bubble dissolution models, and is based on an idealized packing arrangement of powder particles. The predictions are in agreement with experimental observations presented in the literature. The simulation allows for systematic and quantitative studies on the effect of molding conditions and material properties on the molding cycle and molded part density.
Effect of Dynamic Cross-Linking on the Foaming of PP/EMA Thermoplastic Elastomers
Isabelle Pesneau, Michel Champagne, Richard Gendron, Michel Huneault, May 2001
The foaming of PP/EMA thermoplastic elastomers with CO2 during dynamic cross-linking has been investigated. The cross-linking of the EMA phase was obtained through an alcoholysis reaction with 1,5-pentanediol. The cross-linking extent was controled by changing processing parameters and chemical composition (diol content). PP/EMA foams were obtained in different conditions. Results on foam density, cell morphology and cross-linking extend are presented. The effect of cross-linking extend on foamability is discussed.
A New Family of Positive Temperature Coefficient (PTC) Materials Based on Nylon 12
R.H. Croteau, V.M. Shah, J.L. Mead, R.G. Stacer, May 2001
An experimental study has been conducted to establish factors influencing the positive temperature coefficient behavior of particulate-filled nylon 12. Fillers considered included both finely-divided nickel as well as carbon black. Resistivity of the blends was used to determine the effect of filler loading on the conductivity and percolation threshold of this new family of materials. PTC effects of up to nine orders of magnitude were observed as functions of filler fraction, type of filler, etc.
Rubber Toughening of Epoxy-Cyanate Ester Blends for VARTM Applications
Brian S. Hayes, James C. Seferis, May 2001
Blends of cyanate ester resins and epoxies offer unique properties and performance that are midrange between the two materials alone. These blends are attractive due to the lower cost the epoxy resin imparts as well as increased toughness and resistance to crystallization. In this study, epoxy and cyanate ester resin blends were toughened using different liquid rubber modifiers. The adducting sequence of the rubber materials was found to alter the morphology and toughening efficiency of these materials.
Cryogenic Microcracking of Carbon Fiber/Epoxy Composites: Influence of Fiber Type
John F. Timmerman, Matthew S. Tillman, Brian S. Hayes, James C. Seferis, May 2001
Cross-ply laminates were created from model prepregs and evaluated to determine their response to cryogenic cycling. The tensile modulus of the carbon fibers was varied to alter the composite material's properties. Examination of the laminates after cycling provided insight into the mechanism of thermal stress-induced microcracking. Optical microscopy revealed that increasing the tensile modulus of the fibers resulted in a corresponding increase in the degree of microcracking that occurred in the composite.
Microporous Polyolefin Film for Battery Separator
Jang-Hoon OH, May 2001
An experimental study was performed on how microporous polyolefin film was made and how it could be used as battery separator. Effect of various processing variables on the microporous film properties was investigated. To get better microporous film various conditions were to be optimized. Microporous film having smaller pore size, higher porosity and shut down capability was obtained.
Thermal Effusivity as a Void or Delamination Measurement
Christina Chandler, Nancy Mathis, May 2001
Thermal effusivity has been measured on materials that include carbon-carbon aerospace composites, air ship fabric and thin rubber materials. The effusivity, which multiplies thermal conductivity, density and heat capacity, was found to be sensitive to the presence of voids or delamination in the products. The presence of air in the delamination lowers the effusivity as the air has lower thermal conductivity, density and heat capacity when compared to the sample. This triple sensitivity has applications for on-line QC detection during production.
Polymer Kit Project for Grades K-12
Melvin I. Kohan, May 2001
A 5-year Polymer Kit Project (PKP) to bring the story of polymers into the precollege curricula is nearing conclusion. The goals, concepts, guidelines, and problems have been reported previously [1-3] and are briefly reviewed here. The progression in the treatment of five basic concepts as the lesson plans proceed from grade K to 9 is described in this paper.
Composite Tooling for Injection Molding
E. Kent Dawson, John D. Muzzy, May 2001
Aluminum, ceramic, and high conductivity carbon fiber have been used to cast composite injection molds with superior thermal and mechanical properties. Heat transfer and dynamic mechanical analysis experiments showed improved conduction and glass-transition temperature compared to traditional epoxy and stereolithography-based tooling. The master pattern was produced using stereolithography and multijet prototyping technologies. In injection molding experiments, the composite tools required less total cycle time than a comparable stereolithography tool.
Fracture of a TPE Catheter
P.R. Lewis, May 2001
A nylon/polyether TPE catheter fractured during the final stages of childbirth in a British hospital. The catheter supplied an epidural anaesthetic to the patient, and part of the tip was left in her spinal fluid. She sued the hospital and manufacturer. The catheter showed brittle behaviour, and research showed that it was probably caused by a combination of UV and gamma radiation of the polymer, initiating chain degradation. ESEM of the fracture surface showed no cut marks, as suggested by another expert witness. FTIR microscopy showed traces of esters near the fracture, confirming degradation.
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