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 Effect of Liquid Cooling of Gas Channel in the Gas-Assisted Injection Molding Process: Overview
Jun Seok Lee, Sooyoung Cha, Francis Lai, May 2001
In Gas-Assisted Injection Molding, gas channels are usually utilized as a gas transfer system. However, the gas channel can be considered to have dual purposes; it can be used as inner cooling channel to improve fast cooling and to reduce cycle time without losing part quality. In this study, a simple plastics part with an open gas channel is used for prediction of cooling effect when gas channel is acting as a cooling channel by introducing the mixture of gas and liquid. Results can be drawn on how fast the part cooling is and how much the fingering effect reduces. Most importantly, we can compare how the quality differs between the gas-injection molded part with and without internal cooling.
Cracks Prediction of Thin-Wall Injection Molded Part by CAE Simulation
Sooyoung Cha, Francis Lai, May 2001
Cracking in the injection-molded part is one of the problems which tooling engineer and/or design engineer often encounter in the molding process. This phenomenon originates from several factors. Among them are high-speed injection, high/long packing pressure/time, etc. In reality, the cracking may be recognized after long time, i.e. days or weeks after part production. In this study, CAE simulation helped to predict the potential cracking area in the plastics part and possible solution(s) to reduce or eliminate cracking by either redesign the part or changing plastics material or processing conditions through simulations. The part used in this study is from the thin-wall injection molded speaker grille product. In the analysis, this speaker grille would be 3-layer solid that is considered real 3D solid model.
Not All Maleated Polyolefins Are Created Equal
Scott M. Hacker, May 2001
Parameters typically used to optimize the performance of maleated polyolefins in various applications are the level of maleation, molecular weight, and amount of the maleated polyolefin used. However, not all the anhydride functionality present in a maleated polyolefin is covalently bonded, or bound to the polymer backbone. The bound maleic anhydride content is a function of the starting polymer and maleation process. This paper uses a simple analytical procedure to determine bound vs unbound maleic anhydride in maleated polyolefins, summarizes bound maleic anhydride values for selected experimental and commercially available materials, and discusses how the level can impact application performances.
Plasticization with Carbon Dioxide to Facilitate Melt Spinning of High Acrylonitrile Content Materials
Michael J. Bortner, David L. Godshall, Donald G. Baird, Priya Rangarajan, May 2001
The effects of plasticizing Barex, a commercial polyacrylonitrile/methyl acrylate (PAN/MA) copolymer, with carbon dioxide (CO2) are studied. Differential scanning calorimetry (DSC) is used to evaluate the resulting shift in the glass transition temperature (Tg) of Barex following plasticization. Pressurized capillary rheometry is used to evaluate the differences in melt rheology prior to and after plasticization. Dynamic rheology data is used to perform an Arrhenius type analysis that allows an estimation of the shift in processing temperature. An estimated 20°C decrease in processing temperature can be obtained upon CO2 plasticization, which slows the kinetics of the copolymer degradation (crosslinking) at processing temperatures.
Polylactide, A New Thermoplastic for Extrusion Coating
Mark Hartmann, Nicole Whiteman, May 2001
Polylactide (PLA), a new thermoplastic derived from corn, has been developed for extrusion coating applications. Polylactides can be rheology modified to run on high-speed commercial extrusion coating lines to produce packages with unique properties. New packaging systems will be described based on PLA's combination of adhesion, flavor/aroma barrier and heat seal/hot tack strength.
The Use of Encapsulation Dies for Processing Linear Polyolefin Resins in Extrusion Coating
Kelly R. Frey, Gary D. Jerdee, Clint D. Cleaver, May 2001
Traditionally highly branched autoclave low-density polyethylene resins have been ideal for extrusion coating due to their inherent melt strength characteristics. Encapsulation coating dies have been used with other polymers to overcome melt strength deficiencies and improve processing. This study evaluates the effectiveness of encapsulation with linear materials such as high-density polyethylene and linear low-density polyethylene.
Seek Risk©, A Methodology to Quantify Supply Related Risk
Joseph P. McCaul, May 2001
The SEEK Risk© Model was developed as a screening device to identify critical inputs to a firm and assess the effectiveness of countermeasures against potential disruptions. It is also a tool for comparing suppliers. The risk, both mitigated and unmitigated, is evaluated on a logarithmic scale. The assessment considers threats to both supply and technical competitiveness of the organization. The overall risk is scaled to resemble the well-known Richter Scale.
Structure-Property Relationships in Polyamide Based Nanocomposites
S. Bagrodia, L.T. Germinario, J.W. Gilmer, M.R. Tant, May 2001
Polyamides are currently employed in packaging applications requiring high oxygen barrier. The inclusion of small quantities of organo-montmorillonite clay into polyamides leads to an exfoliated clay morphology. By creating a tortuous path for gaseous diffusion, this morphology results in considerable enhancement in the barrier properties of the material. Characterization of the nanocomposite film by X-ray diffraction, transmission and scanning electron microscopy, and atomic force microscopy shows extensive exfoliation of the clay platelets into the polyamide matrix. The clay platelets tend to align themselves parallel to the film surface during the blow molding process. This paper discusses the structure-property relationships in polyamide-based nanocomposites and their utility in high barrier applications.
Flow Analysis in Single Screw Extruders
Adeniyi Lawal, Sudhir Railkar, May 2001
Analysis of flow and pressurization in single-screw extruders can be carried-out using one-, two-, and three-dimensional flow analyses. In one-dimensional analysis, the extrusion flow can be represented by the idealized model flow between infinitely long and wide parallel plates, i.e., the Generalized Couette flow, thus enabling the generation of analytical solutions. In two-dimensional analysis, the screw geometry is unwrapped in the helical direction of the screw and the lubrication approximation applied. For three-dimensional analysis, a mesh is generated which describes accurately the geometrical screw configuration without any unwrapping. For both the two- and three-dimensional analyses, the Galerkin Finite Element Method is utilized in the solution of the governing equations of conservation of mass, and momentum. In this study, the different analyses will be described for the flow of Heschel-Bulkley fluids with wall slip, and simulation results presented and compared for the special case of a Newtonian fluid for three different screw geometries. The limits of application of the different analyses will be discussed.
Comparative Melting Trials in ZSK Extruders
Dong-wu Yu, S.H. Kim, John Curry, May 2001
Twin screw co-rotating kneaders are popularly used as plasticating compounding extruders for a broad range of technical plastics and commodity polymers at high rates. Melting in these devices is always initiated by a combination of kneading disks which effect repeated bulk deformations of the plasticating mass. The resulting melt quality is sensitive to size, shape, and physical properties of the feedstocks, to the configuration of the melting screw, and to operating conditions. Four pelletized polymers were each plasticated using a split barrel ZSK40 configured with two screws and run at two operating conditions. Carcasses were examined in place and by dissection for overall melting lengths and residual particle shape and melt texture.
One-Step Blending and Molding of Glass Fiber Filled Polypropylene - Physical Property Measurements
Rajath Mudalamane, David Bigio, Tomoyasu Hirano, Saeid Zerafati, May 2001
Fiber length retention during incorporation of glass fibers into a polymer matrix has re-gained importance over the past few years. This can be attributed to the introduction of injection moldable long fiber reinforced thermoplastics. The longer fiber length in the feed material results in 5 – 20 times longer fiber in the molded part with significant improvements in final product properties when compared to its short fiber counterparts [1]. Long-fiber composites have been found to exhibit overall higher physical properties compared to their short-fiber analogs. Mechanical properties, elevated temperature performance and creep and fatigue endurance are all higher for long-fiber composites [2]. An indication of how increased fiber length translates into better properties can be seen by burning off the matrix resin from a molded part (see Figure 1). The residue is a three dimensional structure formed by a network of long fibers that retains the original shape of the part. This allows better distribution of stresses throughout the part.
Improving the Reliability and Performance of Microelectronic Packaging
J. Weaver, K.T. Gam, Y. Oh, L. Bonnaud, S. Suh, H.-J. Sue, M. Todd, Q. Ji, M. Edwards, May 2001
Microelectronics is a field currently in high demand considering its many applications. Concerns are raised to improve reliability and performance of high performance packages. To do this, one must first understand the physics behind the failures of these small packages. To do this, non-destructive testing and the use of microscopy to identify the location of failure can be employed. By identifying the mode of failure in these packages, a micromechanics and materials approach can be used to implement a new package that shows a significant improvement in both the reliability and performance.
TiO2 Photochemistry and Color Applications
Dwight A. Holtzen, Philipp M. Niedenzu, Michael Diebold, May 2001
TiO2 is one of the most commonly used pigments in the coloring of plastics. TiO2 not only provides opacity but it is an excellent UV absorber. Hence, the pigment provides opacity and protection for plastics. This paper reviews the sources of TiO2 photochemistry and methods to control photoactivity.
A Next Generation Color Management Tool
Richard Johnston, May 2001
A knowledge-based system allowing for more effective use of color concentrates in plastics has been developed. Software and portable spectrophotometers utilized during processing present a color matching system that functions as a significant new color management tool to both injection molders and machine extruders. Used this way, as a quality or process monitor, the system can manage color consistency and product stability, because the deleterious effects of fluctuations in colorant loading on the physical properties of molded parts can be eliminated.
Modeling Structural Recovery: Analysis of the Peak Shift Method
Yong Zheng, Sindee L. Simon, Gregory B. McKenna, May 2001
Amorphous polymers below their glass transition temperature, Tg, are inherently not at equilibrium. As a consequence, their structures continuously relax in an attempt to reach the equilibrium state. Models of structural recovery can quantitatively describe this process. One of the parameters needed in the models is the non-linearity parameter x. It has been purposed that x can be obtained from experimental data using the peak-shift method. In this work, we use computer simulations to quantify the error in the value of x obtained from the peak shift method.
Rheological Response of Polystyrene/Ortho-Terphenyl Solutions
Xingfu Shi, Paul A. O’Connell, Gregory B. McKenna, May 2001
The linear and nonlinear viscoelastic responses of concentrated solutions of polystyrene in ortho-terphenyl are being investigated. Three aspects of behaviour are being addressed: 1) the time-temperature and 2) the time-concentration dependence of this material system and 3) the time-strain separability of the response in the non-linear regime. Linear viscoelastic responses are being measured using an ARES rotary rheometer and the non-linear response will be investigated using an RMS7200 where both the torque and normal force response in torsional deformations will be measured. The polymer is a commercial specimen having a weight average MW of 192,000 g/mol. Concentration is being varied between 0.2 and 0.7 mass fraction of polystyrene. Since time-strain separability is fundamental to the tube theory of reptation, the non-linear response will be discussed in the reptation framework.
Swelling as a Method of Discriminating among Strain Energy Functions
Gregory B. McKenna, May 2001
The swelling of cross-linked elastomers is generally treated with the Flory-Rehner[I] theory. One aspect of the common use of the theory is the simplification of the form of the elastic strain energy function such that it appears as the shear modulus G(?) in the swelling equilibrium equations. A more general form of the relevant equations would be to use ??A(?)/?(?1/3) where A is the Helmholtz free energy of the network, ? is the volume fraction of polymer in the swollen system. Here we examine the limitations put on the form of the strain energy density function (A) when the shear modulus is observed to scale as ?1/3.
Isotropic Residual Stresses in Thermosetting Resins: Modeling and the Effects of Resin Modification Properties
Mataz Alcoutlabi, Gregory B. McKenna, Sindee L. Simon, May 2001
Recently, we extended a thermo-viscoelastic model [1] to describe the development of isotropic residual stresses for a commercial thermosetting material during cure [2]. In this paper, we extend this model to study residual stresses in novel thermosetting resin systems, such as spiro orthocarbonate/bismaleimide (SOC/BMI) which are under consideration by the Air Force for use as polymer matrix composites. In these systems, cure shrinkage and isotropic residual stresses are reduced through a ring-opening reaction which occurs independently of the addition reaction. The modeling effort includes a parametric analysis of the effects of various parameters, including the volume changes involved in the reactions, the relative rates and orders of the reactions, and the dependence of the glass transition on the network formed.
Large Deformation Response of Polycarbonate: Time-Temperature and Time-Strain Superposition
Paul A. O'Connell, Gregory B. McKenna, May 2001
Data are presented from tests of the stress relaxation response of a glassy polycarbonate under torsional deformations. Tests were performed on samples over a range of strains from 0.0025 to 0.07 and at temperatures from 30 EC to 135 EC, all at a fixed aging time of 64800 s. Individual data sets at each strain and temperature could be described using a stretched exponential form relaxation function. Over the range of temperatures studied the data at each strain could be superimposed using conventional time-temperature superposition. For strains up to the yield strain the data at each temperature could also be superimposed to form a master curve following the principle of time-strain superposition. Interestingly, the master curves found from time-strain superposition at each temperature did not have the same form. Similarly, the master curves found from time-temperature superposition at each strain did not have the same form.
Comparative Study of Structure and Property of Ziegler-Natta and Metallocene Based Linear Low Density Polyethylene in Injection Moldings
Y. Ruksakulpiwat, May 2001
Linear low density polyethylenes (LLDPE's) polymerized using metallocene and Ziegler-Natta catalyst were used to study the shear-induced crystallization in injection moldings. The gapwise distributions of crystallinity, spherulite size and thickness of the shear-induced crystallization layer in moldings were measured along with the mechanical properties of the moldings. The effects of processing conditions on these properties were determined. Metallocene based LLDPE shows higher thickness of skin layer, lower spherulite size and higher degree of crystallinity than Ziegler-Natta based LLDPE.

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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
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