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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
Improved Processing of Highly Filled Calcium Carbonate Compounds
Mike Fulmer, John vander Kooi, E.K. Koss, May 2000
Calcium carbonate treated with an interfacial agent, such as stearic acid or stearate, will typically wet or lubricate its surface resulting in lower viscosity than untreated calcium carbonate. In this paper, the effects of fatty acid derivatives on highly filled calcium carbonate both treated and untreated, in polypropylene compounds will be discussed. The use of fatty acid derivatives can be effective for lowering extrusion pressure, leading to throughput increases. The overall effect on filler addition, viscosity, mixing and processing properties will be shown for one class of fatty acid derivative.
INDEX™ Interpolymers: New Materials for the Wire and Cable Industry
S.R. Betso, M.J. Guest, R.M. Remenar, A.W. Field, F.E. Keen, May 2000
INDEX Interpolymers, including ethylene/styrene Interpolymers, are a new family of polymeric materials that are being utilized in a variety of durable applications. Unique structural parameters, material characteristics, and property combinations, including processibility, that make these new polymers ideal candidates for a variety of wire and cable applications are described. Materials engineering possibilities, including the incorporation of specific filler types and loadings, allow the formulation of materials with property balances of benefit to the industry, including applications that require low smoke generation. A variety of wire and cable applications are summarized and the benefits of the Interpolymer formulations highlighted.
Evolution of Structural Hierarchy in Uniaxially Deformed Branched Poly Lactic Acid Films as Followed by Spectral Birefringence Technique and Others
G. Kokturk, T.F. Serhatkulu, M. Cakmak, May 2000
Over the past two decades, the lactic acid homo and copolymers have been extensively investigated for a variety of medical and pharmaceutical applications; including wound closure1, dental repairs2, fracture fixation (bone plates, screws, pins, and splits)3, ligament reconstruction, vascular grafts4, nerve repairs5 and drug delivery6,7. They are also extensively used in controlled drug release area6-8. With the recent developments in the technologies for purification of the raw materials, the large scale usage of these lactic acid based polymers became quite feasible. This, in turn, is opening the door for application particularly in the biodegradable packaging.
The Effect of Titanium Dioxide Particles on the Deformation Behavior and Orientation Development in PET Films
Atsushi Taniguchi, Miko Cakmak, May 2000
The effect of TiO2 particles on the stress-strain behavior of PET films from amorphous precursors at a series of compositions and deformation temperatures were investigated. TiO2 particles act as a nucleation agent and enhance the thermally induced crystallization of the PET chains. However, when stretched from the amorphous state, the TiO2 concentration levels as low as 0.35wt% was found to reduce the overall stress and retard strain hardening and accompanying strain induced crystallization. As a result, under the same stretching conditions, the films containing TiO2 were found to possess lower crystallinity and orientation levels. This was attributed to the reduction of chain entanglements in the presence of these small amounts of TiO2 particles in the stretching process. The results on the structural hierarchy developed in stretched and heat-set films will be presented.
The Effect of Deformation and Composition on the Structure Evolution in the Pre-Oriented PET/PEI Blend Films during the Heat Setting Process
Jonghan Choi, Miko Cakmak, May 2000
The objective of this research is to affect the deformation and thermal behavior PET through synergistic blending strategies. For this purpose, a series of crystallizable compositions of PET (Tg=70°C) and PEI (Tg=215°C) were prepared. The structure evolution during uniaxial deformation was investigated. The very fast structural rearrangement processes that take place during the heat setting process were investigated using the newly developed Spectral Birefringence Technique. In 100/0 PET/PEI samples, above the onset of strain hardening the birefringence rapidly increases with time. The total increase in birefringence decreases with the increased levels of orientation and crystallinity imparted during the stretching stage. The introduction of PEI and the increase of its concentration tend to dilute the crystallizable PET chains. This, in turn, introduces a relaxation step at the early stages of heat setting at 180°C even in samples that were stretched to high stretch ratios. We also demonstrated that our Spectral Birefringence Technique is fast enough to keep up with the very rapid changes that take place at 180°C where the fastest crystallization is experienced.
Investigation of the Phase Behavior of Blends of Poly(benzoyl paraphenylene) and Various Thermoplastics
Yung-Hoon Ha, Chris E. Scott, Edwin L. Thomas, May 2000
Substituted poly(paraphenylene) derivatives (PX) have recently been synthesized which are purely amorphous, soluble in various common solvents, and have excellent mechanical properties. [1] However, the blend behavior of these polymers has been relatively unexplored. Here we report the phase behavior of PX blended with various thermoplastics such as polyetherimide (PEI), polystyrene (PS), polymethyl methacrylate (PMMA), poly(ethylene-co-cyclohexane dimethylene terephthalate) (PETG), and polycarbonate (PC). The PX/PC blends are of special interest since these appear miscible over its entire composition up to at least 205 °C and possess a lower critical solution temperature (LCST).
Effect of Silane on Mechanical Properties of Dental Resins
A. Karmaker, A. Prasad, May 2000
Silanes are commonly used in composite materials to promote adhesion between fibers and resins. Silane can be used to treat the fiber surface or mixed with resin before fibers are embedded into the resin. In latter case, some excess silanes can remain in the resin that may change its physical properties. In this study gamma-methacryloxypropyltrimethoxysilane was added to the dimethacrylate based dental resin at different weight percentage. Both visible light and heat curable initiators were added to the resin formulations. The effect of silane on mechanical properties was investigated from flexural tests in accordance with ISO 10477.
Improvement in Capillary-Driven Flow by Surface Modification of Polystyrene Surfaces
John D. Clay, May 2000
The goal of this work was to improve capillary-driven flow through small channels on a polystyrene plaque. This work was driven by the requirement to move biological fluids on a diagnostic device using only a capillary driving force. Polystyrene surfaces were modified with a hydrophilic coating to increase the surface energy. Changes in the surface energy were quantified by contact angle analysis. Capillary flow through the treated and untreated channels was captured on video using several liquids with known surface tensions. Results from the surface modification work and implications for capillary-driven flow on medical devices will be presented.
Roving Impregnation with Thermoplastic for Pultrusion
R.A. Becerra, B. Sanschagrin, May 2000
The pultrusion process was created for high performance products, especially for high fiber/matrix ratio. In the past few years, the pultrusion of thermoplastic reinforced composites has been growing steadily because it offers a cost / performance benefit. In this study, we have been working on a new way of impregnating the fiberglass roving that does not require an extensive modification of the existing pultrusion line. This has been achieved by dividing the impregnation process into three steps. Firstly, a monomer/polymer solution impregnates the fibers. Then, the roving passes through an oven ending the polymerization and evaporating the excess of monomer. Finally, the roving is covered with a small amount of melted thermoplastic in order to achieve a higher quality product. This technique has been proven effective with PS and PMMA, two amorphous polymers that can be obtained by bulk polymerization.
Calcium Carbonate Filled Polybutyleneterephthalates
Ma’an Sardast, Kyung-Ju Choi, May 2000
70% of fillers used in plastic materials are calcium carbonates due mainly to availability and cost advantages. The raw material cost of polybutylene terephthalate (PBT) is relatively higher than most of polyolefins and common polyesters. It has been reported that calcium carbonate filled polyester reduces shrinkage of the product substantially. Mineral filled plastic compounds burn much more slowly than their unfilled counterparts. Lowering raw material cost without having much adverse effect on properties by blending calcium carbonates is the objective of the current study. Rheological, thermal and mechanical analyses were carried out with virgin and up-to 15 weight percent of calcium carbonate filled PBTs. Rheological and thermal properties of filled PBTs comparing with virgin PBT had not changed noticeably while the percent elongation to break decreased and the modulus increased with increasing filler content.
Influence of Thermoforming Parameters on Final Part Properties
G.W. Harron, E.M.A. Harkin-Jones, P.J. Martin, May 2000
This paper continues the work conducted into the influence of extrusion parameters on sheet for use in the thermoforming of food packaging. The quality of thermoformed parts may be measured in terms of physical appearance and mechanical properties. The objective of this work is to identify the critical variables in the process. The process parameters tested include plug geometry, plug depth, plug temperature and air pressure. The thermoforming properties investigated included wall thickness distribution, compressive strength, plug force and pot weight. The main findings of the study were that five factors govern the wall thickness distribution and the resultant distribution controls the compressive strength of the pot. It has been shown that it is possible to measure sheet deformation forces using a force transducer in the plug.
Investigation of Heat Transfer in the Plug Assisted Thermoforming Process
P. Collins, J.F. Lappin, E.M.A. Harkin-Jones, P.J. Martin, May 2000
A Finite Element model of the plug-assisted thermoforming process has been developed to encompass both 2D axisymmetric and more complex 3D geometry. Initial modelling attempts assumed isothermal conditions, but for further improvement it is necessary to investigate the effects of heat transfer. In this paper the effects of heat transfer on the process are investigated. Heat transfer behavior at the plug and mold interfaces was identified and validated with the use of simple tests. The results were incorporated into the model of the thermoforming process and an improvement in wall thickness prediction has been demonstrated.
The Use of Hot Impact Testing in the Simulation of the Plug-Assisted Thermoforming Process
N.J. Martin, J.F. Lappin, E.M.A. Harkin-Jones, P.J. Martin, May 2000
In mathematical simulations of thermoforming processes, one of the most difficult problems lies in developing realistic models of the behaviour of plastics at forming conditions. This paper investigates the use of a low cost modified impact test to obtain material data. A conventional falling weight impact tester has been modified by inserting an oven and replacing the metal indenter with various plug shapes. This creates loading conditions which are very much similar to the real process and the resulting force-displacement data may be converted to true stress-strain data. A range of thermoplastic materials have been tested using this method and the results are presented in this paper.
Crystallization of Isotactic Polypropylene: Comparison between ? and ? Growth Rates
Y. Mubarak, E.M.A. Harkin-Jones, P.J. Martin, M. Ahmad, May 2000
The influence of a white pigment (White MB PE) and a nucleating agent (Millad 3899) on the spherulite growth rate of isothermally crystallized iPP was investigated by polarizing optical microscopy. Lauritzen and Hoffman analysis was used to determine the kinetic parameters of the growth rate. It was found that the addition of either pigment or the nucleating agent caused a reduction in the spherulite growth rate. This was attributed to the increase of the energies required for the transportation of the macromolecules in the melt. Over the crystallization temperatures used in this study, higher growth rates for ?-spherulites have been obtained in comparison with ?-spherulites. Nucleation densities for the nucleated samples, (FINA4042S and iPP containing 1wt% Millad 3988), were greater than those of either plain iPP or the samples containing the white pigment.
New Rapid Tooling Concepts
Falk Lindner, W. Michaeli, May 2000
Within the scope of Rapid Tooling the IKV is working on the optimization of Soft Tooling techniques and on the development of Hard Tooling techniques. The aim is to get molds with a high mechanical strength and series-like cooling conditions. For that purpose the resin casting process is improved taking advantage of the sedimentation of a steel powder filler. Furthermore the metal injection molding (MIM) is analyzed with respect to its suitability for manufacturing steel molds or prototypes. The mold used in the MIM process is made by stereolithography. The results show the possibility to get steel powder contents as high as the bulk density with the resin casting. It is also feasible to manufacture green parts of steel molds or prototypes with MIM.
Gas-Assisted Reaction Injection Molding (GRIM): Application of the Gas Injection Technology to the Manufacturing of Hollow Polyurethane Parts
I. Kleba, E. Haberstroh, May 2000
The gas injection technology is gaining constantly in importance for thermoplastic polymers and could also offer a great potential of application to the manufacturing of polyurethane parts. Due to the significant differences concerning the material behavior between thermoplastics and reactive PU systems with their coupled chemical and physical processes this molding concept, designated as Gas-assisted Reaction Injection Molding (GRIM), has been investigated. Numerous experimental investigations concerning the most significant process parameters as well as a rheokinetic characterization have been performed. A selection of the results is presented within this paper.
Modelling and Validation of the Blow Moulding of HDPE/Nylon Multilayer Containers
A. Meddad, P. Debergue, A. Garcia-Rejon, R. DiRaddo, May 2000
A large growth area for blow molding is in automotive applications. The benefits of plastic for automobiles include (a) lower investment costs for plants and tooling, especially for high production volume, (b) ability to tailor the material to obtain desired barrier and chemical resistance properties and (c) reduced car weight and cost. Recent trends in blow moulding are towards the use of multi-layer sequential material processing. The introduction of multi-layer processing has contributed to increase the number of potential markets for blow molding. This study shows the effect of the processing parameters on the wall thickness distribution of each layer in the final multi-layer blow molded product. Some experimental results are compared to simulation predictions obtained by employing an integral viscoelastic material model (K-BKZ).
Modeling the In-Mold Coating Process of Thermoplastic Substrates
Suneel Vadlamudi, Jose M. Castro, Elliott J. Straus, May 2000
In-mold coating (IMC) is being successfully used as a primer IMC to cover surface defects such as porosity and sinks, for Sheet Molding Compound (SMC) compression molded automotive and truck exterior body panels. A new class of coating materials is being developed [1, 2] for thermoplastic substrates. The potential benefit of using In-mold coating (IMC) as a topcoat for thermoplastics is large. Painting is a very costly and a non-environmentally friendly operation. Key to optimizing the IMC process is to be able to predict the fill pattern, so as to locate the injection nozzle or nozzles, in locations where the potential for trapping air is minimized [3, 4]. CAD software is available [4] to predict the flow of IMC, when the substrate compressibility can be neglected. However, for SMC parts with large regions parallel to the mold closing direction (most truck parts) and in particular for thermoplastic parts, the substrate compressibility cannot be neglected. Our long-term research aims to develop a simulation package that predicts the flow of IMC when the substrate compressibility cannot be neglected. In this paper, a simple model to predict the pressures needed to inject the coating as a function of the substrate compressibility is presented. We will also show how the clamping force needed to prevent the mold deflection can be estimated.
Biodegradable Plastic Materials in Blends for Cost-Effective Low Temperature Applications
Andrea Komarek, John Uhlrich, Pete Sherlock, Christopher C. Ibeh, May 2000
An on-going Pittsburg State University project focuses on the development of biodegradable polymer blends that can be used for low temperature durable and cost-effective bioresorbable castration clips for the farm industry. Clip materials must be non-food contaminants while being functional at the below zero degree polybutylene succinate and polybutylene/adipate copolymer were formulated into injection moldable blends that can withstand down to -20°C (negative 20 degrees Centigrade)."" weather of the North American farm belt winter months. Using the glass transition temperature (Tg) and solubility parameter (?) criteria pre-selected biodegradable materials polycaprolactone
Improving Accuracy of Blow Molding Simulation
Jay Z. Yuan, Christopher J. Matice, Balakrishna Haridas, May 2000
Finite element analysis has revolutionized the design of blow molded parts. Using FEA an analyst can predict material distribution in blow molded parts and evaluate part performance prior to prototype molding. However, many finite element analysis procedures make use of shell-element formulations, whereby the parison or preform is modeled as a thin shell. In this paper we present a simulation of blow molding a bellows in which the shell-element formulation results in incorrect calculation of material distribution and offer an improved simulation using continuum elements. The importance of modeling the heat transfer within the melt as it contacts the mold wall is also illustrated.

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