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.
The SPE Library is just one of the great benefits of being an SPE member! Are you taking advantage of all of your SPE Benefits?
Conference Proceedings
Extrusion Foaming of PET/PP Blends
C. Wan, M. Xanthos, S. Dey, Q. Zhang, May 2001
In order to develop new applications for recyclable commingled resin streams, blends containing PET and PP resins with different rheological characteristics were dry blended or compounded at different ratios and subsequently foamed by using PBAs and CBAs. Properties of the foamed blends were compared with those of similar products obtained by foaming the individual PET and PP components in the absence of compatibilizers/rheology modifiers. Foamed polymer blends with fine cell size and low density could be produced in the presence of suitable compatibilizer systems consisting of functionalized polyolefins or their combinations with reactive coagents
Compression Molding Tooling for Thermoplastic Composites
Harold F. Giles, Jr., May 2001
Tooling requirements for compression molding continuous glass mat, long fiber glass, or other types of reinforced thermoplastic composite products is presented along with critical tooling aspects. Emphasis is placed on the general tooling concepts associated with cooling lines, shear edges, guidance systems, ejectors and stop blocks. Basic product design issues that can lead to poor part performance i.e. weld lines, tabs and mounting holes, ribs and bosses, sink marks, multiple cavity molding, and venting are discussed. The relationship of prototype tooling and the requirements to go from design to production is discussed briefly.
A Physical-Mathematical Model for the Description of the Process Behavior of Mixing Elements
H. Potente, K. Kretschmer, J. Flecke, May 2001
Tightly intermeshing, co-rotating twin screw extruders are commonly used for tasks requiring good mixing. The modular constitution of both barrel and screw makes it possible to optimize the extruder configuration for a given task. Physical-mathematical models enable the process engineer to predict the process behavior of a chosen extruder configuration and to optimize existing compounding processes. We will present physical-mathematical models for the prediction of the pressure-throughput relationship of grooved conveying and grooved reconveying elements. The models are based on an analytical approach for the description of the flow patterns within the investigated screw elements. Experimental investigations were performed with varying geometry, material and process parameters. Finally the developed model was compared to the experimental results.
Extrusion/Compression of Long Fiber Thermoplastic Composites
Klaus Gleich, May 2001
It is becoming common for long fiber-reinforced thermo-plastics (LFT) to replace existing GMT-type applications as well as to capture new applications. This is especially true in the European automotive industry, where the market for parts made from LFT is experiencing tremendous growth. The following paper discusses the available materials, the mechanical and physical properties, machine techniques and processing details of the LFT process. It will also discuss potential applications for LFT. The paper will cover different process techniques such as direct processing and make comparisons with other processes. An explanation on the effects that LFT has on properties and economics will be made. It will show how the economics can be improved by adding recycled material to the process. This paper will provide a better understanding of the LFT-process and how you could get benefits from this process.
Interaction in PC/ABS Blends Prepared in a Dynamic Melt Mixer
Károly Belina, Péter Juhász, Desi Csongor, Nick R. Schott, May 2001
Polymer blends are more and more important materials in polymer technology. Their role increases due to the recycling processes of mixed plastic waste. One of the key problems of polymer blends is the interaction between the components as they determine the properties. Commercial polycarbonate (PC) and ABS were blended in a dynamic melt mixer in 80/20 and 70/30 ratios. Homogeneity of the blends was characterized by SEM method. Glass transitions of the blends and the pure materials were measured by calorimetric and dynamic mechanical analysis. The interaction and the partial miscibility between the components were determined from the shift of the glass transition temperatures. It was found that the homogeneity of the blends was uniform. The shifts of the glass transition temperatures show some interaction between the components.
Melt Modification of PET with Reactive Glycidyl Compounds
R. Dhavalikar, M. Xanthos, May 2001
Melt strength of polyesters for foam extrusion and extrusion blow molding is controlled by weight-average molecular weight, molecular weight distribution, and the degree of branching. This paper describes the chemical modification of polyethylene terephthalate (PET) as a technique to improve its melt strength using compounds containing the reactive glycidyl (epoxy) group. The effect of addition of di-, tri-, and tetra- functional epoxy compounds to the PET resin in the melt state was studied using a batch mixer. Changes in the torque and temperature in the mixer resulting from the addition of modifier(s) were followed in order to relate to the kinetics of the reactions.
Barrier Screws in Helically Grooved Barrels: Operating Characteristics and Implications for Simulation Models
Daniel Schläfli, Yves Zweifel, May 2001
Grooved feed zones in single screw extruders have been used in many variations over the years, mostly axial grooves in many sizes and shapes. The lesser known helically grooved feed zone permits, when properly designed, an operating mode where flow rate becomes a function of geometry only, practically independent of friction coefficients. Therefore, it has a linear behaviour with screw speed and is virtually independent of backpressure over a wide operating range, as shown by experimental evidence gathered over many years. The high flow rates obtained require barrier screws for adequate melting capacity. In the barrier zone, considerable pressure differentials are observed between the primary and secondary channel, where the melting occurs, at higher screw speeds. This effect is associated to the melting mechanism.
Effects of Material and Process Parameters on the Degree of Groove Replication in DVD Disks
W.C. Bushko, I. Dris, A. Avagliano, May 2001
Information storage devices such as re-writable DVD (DVDRW) disks require high degree of groove replication to achieve desired readability. Higher levels of replication are typically achieved by increasing mold temperature, packing pressure, and filling speed. These extreme molding conditions are often on the border of the material processing window. A simple groove forming process model is presented. The model is shown to predict well groove replication for wide ranges of mold and melt temperatures and two different radial locations. The model is useful in assessing replicability of new materials in new formats.
Design of Experiments to Optimize the Weldline Strength in Injection Molded Thermoplastics
Shih-Jung Liu, Jun-Yu Wu, Jer-Haur Chang, May 2001
The forming of weldlines wherever polymer flow fronts meet is one of the problems that confound the overall success of injection molding technology. An L'18 experimental matrix design based on the Taguchi method was conducted to optimize the weldline strength of injection molded thermoplastics. Experiments were carried out on an 80 ton injection-molding machine. A plate cavity with an obstacle at the center was used to create a weldline. After molding, the weldline strength of the parts was measured by a tensile tester. For the factors selected in the main experiments, melt temperature and mold temperature were found to be the principal factors affecting the weldline property of injection molded thermoplastics. In addition, weldline strengths of injection molded parts increase with the size of the obstacles.
Practical New Applications for an On-Line Rheometer
Donald De Laney, Steven Oliver, May 2001
On-line rheometers have been around for over 30 years. They have been used in many different applications in R&D, polymerization processes, product development, and compounding. However, their main application has been in large volume resin production, mainly in the polyolefins industry. Applications in the processing and compounding industries have been almost non-existent because of the large size of the rheometers and the need to modify the extruders or compounders in order to use them. This paper discusses applications of a new rheometer, developed to address these problems, in the monitoring of a production PET sheet extrusion line. The real time" monitoring of viscosity and its application to the control of the resin moisture level and the consistency of a virgin/regrind blend is demonstrated and discussed."
A New Method of Rheological Analysis for Polymer QA and Product Development
Donald De Laney, Jeffry Sweinhart, May 2001
For many years the capillary rheometer has served as an important tool in R&D and product development laboratories. It has even gained in popularity in the QA laboratory as a tool for assuring the processability of a resin. More recently two and even three barrels designs of the capillary rheometer have become more generally available. The main applications of these instruments have been for providing directly corrected viscosities and for doing measurements of extensional properties. However, very little has been said about the opportunity these rheometers provide for applications in QA and product development. This paper discusses the capabilities of the dual barrel rheometer for direct comparisons of materials in QA and for the fast and easy observation of changes in the flow properties of a new product, as it is modified in the development process.
Accuracy of Filling Analysis Program
Keita Ainoya, Osamu Amano, May 2001
In order to verify the accuracy of the filling analysis program (C-MOLD) for injection molding, pressure losses across four characteristic segments (Nozzle & Sprue, Runner, Gate, and Cavity) of the flow channel in the test mold were measured for the HDPE under various molding conditions regulated exactly. Without the additional assumptions in the simulation, the flow properties with the pressure-dependent viscosity and the juncture loss measured actually were added to the indispensable pvT-data, thermal conductivity, specific heat for simulation. After confirming good agreement between the observation and the simulation at the flow segment wherein thermal properties affected weakly on the pressure loss, the effects of the heat transfer coefficient between the polymer and the mold metal on the simulation were examined. By introducing the heat transfer coefficient of 1,200W/m2-K, instead of the default value of 25,000 W/m2-K, we found that the difference between the simulated and the observed pressure losses at the four segments were reduced to less than 20%.
Water Structure in Hydroxyethyl-Co-Glycerol Methacrylate Materials
G. Gates, J. Harmon, J. Ors, P. Benz, May 2001
Differential scanning calorimetry was used to analyze the state of water in crosslinked glycerol methacrylate and hydroxyethyl methacrylate hydrogel polymers. Glass transition temperatures were obtained for the dry materials and for the materials equilibrated at room temperature (23°C) and humidity (55% relative humidity). The total crystallization enthalpy was determined for these hydrogels equilibrated in water and at several states of partial hydration. The enthalpic information was used to quantitatively determine the fraction of nonfreezing water in the hydrogels. The integrated areas of the crystallization exotherms were reported to qualitatively access the freezing-bound and free water contents.
Integrated Design Environment Enhancing Concurrent Engineering Approach in Plastic Injection Molds Design
A. Pipino, E. Indino, A. Franz, M. Thornagel, R. Curado, May 2001
As the injection mold market increases, Time and Costs Reduction will be important aspects for mold makers. A detailed analysis of todays workflow in the mold making industry has pointed out the need for tailored tools in an integrated environment. The COSMOS project, (a pre-competitive European Union founded project) wants to enhance CAE integration and data exchange in CAD-based mold design. A PDM-based (Product Data Management) environment is being tuned on the basis of a new Concurrent Engineering-based approach. The expected results will lead to a reduction in time-to-market by about 30% and cost of about 40% as compared to the traditional injection mold design and manufacturing paradigm.
A Physics Based Approach to Determining Filled Volumes within a Corotating Twin Screw Extruder
Paul Elkouss, David Bigio, Gregory Walsh, May 2001
Determination of filled regions in extruders is important to the understanding of the operation of the extruder. This information can be useful to predict various performance measures for unit operations such as mean residence time and chemical conversion. A model is proposed that predicts the filled volume length for the extruder, based on the pressure drag flow model. This model is dependent on the system geometry in addition to the conveyed fluid's properties. Experiments have been performed that shows the ability of this model to predict the filled length in Co-rotating Twin-Screw Extruder (CoTSE) based upon a determined channel percent drag flow and specific throughput.
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.
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.
.jpg)
.jpg)
.jpg)
.jpg)
