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
Rheological and Mechanical Properties of Recycled Polycarbonate
Ruifeng Liang, Rakesh K. Gupta, May 2000
Polycarbonate (PC) is used in computer and electronic housings, and here it was sought to reuse this polymer after having been separated from electronic shredder residue. The separated stream was not pure PC; there was some cross-contamination. The separated polymer was characterized by rheological, thermal and mechanical methods; the measured properties were only slightly inferior to those of comparable virgin materials. Recovered plastic and virgin polymer were blended using a TSE to determine the minimum virgin content needed to mask the effects of addition of recycled material on the rheological and mechanical properties of the blend. Differences in processing behavior and mechanical performance of the blends as a function of composition are discussed in relation to potential material recycling strategies.
Crystalline but Fully Transparent - A New Polyamide with Outstanding Properties
Hans-Peter Hauck, May 2000
Requirements for chemical resistance and transparency are usually mutually exclusive in plastics, especially for polyamides. While aromatic constituents are used to produce most amorphous polyamides, this new transparent polyamide (designated according ISO 1874: PA PACM 12, herein PA means polyamide, PACM = Bis(p-aminocyclohexyl) methane) is based on aliphatic monomers. The monomer building blocks form very small crystallites that do not scatter visible light, so consequently parts made of this polyamide are clear as glass. This so called microcrystalline structure counts for a well-balanced combination of properties, e.g. good UV-stability, high level of impact behavior, low water absorption and isotropic shrinkage. Especially its chemical resistance is superior to other transparent materials such as polycarbonate, polymethacrylate or all amorphous polyamides.
Small-Scale Testing for Brittle-Tough Transitions of Rapid Crack Propagation in PE Pipelines
Paul Davis, Stuart Hillmansen, Patrick Leevers, May 2000
The resistance to Rapid Crack Propagation (RCP) of extruded PE pressure pipe undergoes a well defined brittle-tough transition with increasing temperature. Material developers need to correlate the transition temperature with property data measured using coupon-sized samples. This paper discusses mechanisms underlying transitions in pipe specimens before presenting efforts to correlate transition temperatures of pipe with small-scale test results. A non-mechanical thermal analysis technique appears to correlate the phase transformation behaviour of raw materials with transition temperatures of extruded pipe.
The Effect of Boron Nitride on the Processability of Metallocene Based LLDPE
Sang Myung Lee, Jung Gon Kim, Jae Wook Lee, May 2000
Melt fracture of a various shapes and related processing instabilities continue to limit processing rate in many commercially important polymer processing industries such as fiber spinning, film blowing and extrusion. Therefore, the occurrence of melt fracture needs to be limited in order to produce high quality products, which have the desired physical properties. In an effort to investigate increasing the processing rate and improving the quality of the final product, a commercial LLDPE was modified by the addition of small amount Boron Nitride (BN). BN was added to the virgin LLDPE at 180°C at concentrations of 0.05, 0.1, 0.5, 0.75 and 1.0 wt %. Also, the processability of capillary flow was investigated as functions of temperature, applied shear rate and L/D for the virgin LLDPE and LLDPE containing BN. The equipment used in this study include capillary rheometer, parallel-plate rheometer and universal test machine (UTM). The degree of processability in the capillary flow was found to depend on boron nitride concentration. The relationship between the apparent characteristic relaxation time and the critical shear rate for the onset of melt fracture and slip is also discussed.
The Comparison of Newly Proposed Cavity-Variable-Based Full Factorial Design and Artificial Neural Network in Injection Molding Process
Jung Gon Kim, In Ho Shin, Jae Wook Lee, May 2000
The statistical experimental design has been used to generate useful information for injection molding process, where more precise models based on physical laws and linear relations are not available. Until now, attempts at applying traditional full factorial design have resulted in creation of many problems, due to the selection of experimental variables from the machine rather than the cavity mold. Injection molding process has plenty of variables to be carefully observed concerning parts quality. Among these, cavity pressure and temperature are the ideal candidates for process monitoring and quality control role, thanks to their capability to present the dramatic changes inside the mold.
Reclamation of Rubber Crumb from Army's Discarded Tires
Kal R. Sharma, May 2000
Polybutadiene is obtained by acid washing the rubber tires followed by thermal treatment of the devulcanized component of the pulverized rubber powder. The process consists of tire grinding and pulverizing steps, a devulcanizing step to reduce the cross-link density, followed by thermal polymerization of the aromatic vinyl mononers and grafting of the polybutadiene followed by melt filtration of the carbon black and the steps of finishing and packaging. The devulcanizing yield can be improved by providing a cocuurent leaching step. This is compared with the yield by the in situ thermal grafting concept.
Model-Free Kinetic Analysis of Epoxy Cures
Sergey Vyazovkin, Nicolas Sbirrazzuoli, May 2000
The application of the model-free isoconversional method to differential scanning calorimetry data allows one to study the mechanism and kinetics of epoxy cures. The method yields a dependence of the effective activation energy on the extent of cure. This dependence can be effectively used to draw certain mechanistic conclusions as well as to predict the reaction kinetics outside the region of experimental temperatures. The applications are illustrated by simulations as well as by epoxy-anhydride and epoxy-amine cures.
Broad Shear Rate Viscosity Measurements via Reconstruction of Fluid Velocity Profiles in Contaminant Melts
David W. Riley, Jim Reilly, Andrew H. Schall, May 2000
A method of building velocity profiles from through the thickness, in situ, optical observations in polymer melts is discussed. It is shown that it is not necessary to know particle position across the thickness of the slit to allow for accurate shear rate determination. Coupled with a pressure drop measurement, the accurate velocity profile is transformed in a broad band viscosity vs. shear rate curve. Controversial resolution limitations are discussed along with experimental data.
Comparison of Experimental and Predicted Data for Conventional Single Screw Extruders
Petra Samsonkova, Jiri Vlcek, May 2000
Single screw extrusion is widely used in the processing of thermoplastic materials. Good understanding of the extrusion process can save time and capital investments. Simulation programs capture the solids conveying, melting and pumping behavior to help us study the process and eventually to fit the screw design to a particular thermoplastic material. From such a study, the best processing conditions may be determined. There is still a considerable lack of understanding of the physical process in an extruder particularly with regards to the solids conveying. Our objective is to contribute to the understanding of this process, which should lead us to an improvement of the solids conveying model. In this paper we present a set of experimental data measured on various screw designs, for varying properties of different PE resins. Further more, the comparison of measured and predicted data is presented. This comparison is used to evaluate the physical model used during simulation of the extrusion process.
Simulation of the Micro Injection Molding Process
Oliver Kemmann, Lutz Weber, Cécile Jeggy, Olivier Magotte, François Dupret, May 2000
To predict the filling process of micro injection moldings, a dedicated 3 dimensional software is under development. The algorithm is based on automatic re-meshing of the varying flow domain. Currently, viscous flow calculations are performed, while visco-elastic effects will be addressed at a later stage. To verify the results, micro injection molding trials with different polymers were carried out. Therefore, new test structures, realized by means of the LIGA technique, were designed. Visco-elastic effects like unique shapes of the frozen flow fronts have been observed, which leads to a new interpretation of micro mold filling.
Vacuum Stamping of a Refrigerator: Identifying Problems through Numerical Simulation, Solving Them and Validating the Solution on the Production Line
Nikos G. Pantelelis, Thierry M. Marchal, Prodromos Megisidis, Laurent Fondin, Andreas E. Kanarachos, May 2000
Thermoforming is gaining more and more applications because of its comparatively easy and fast process. With thermoforming either small (yoghurt pots) or large (refrigerator panels) flat parts can be moulded and a complete description of the process can be found. On the other hand, to simulate the thermoforming process is a real challenge, as various factors have to be investigated and taken under consideration if we want to achieve a realistic simulation. At the present paper, a very complicated thermoforming process is simulated using finite element and other numerical tools and the results are compared to the real process. Moreover, problems occurred in the real process are solved using the simulation tool.
Extrusion of Polystyrene Microcellular Foam with Supercritical CO2
Xiangmin Han, Kurt W. Koelling, David Tomasko, L. James Lee, May 2000
The continuous production of polystyrene foam with supercritical CO2 is achieved by injection of CO2 into the extruder barrel at a certain pressure and rapid pressure release in the die. The effects of temperature, pressure, and die shape, are analyzed in detail. Fundamental work related to the foaming process is accomplished by modeling the phase equilibrium with the Sanchez-Lacombe equation of state and combining the equations of motion, the energy balance and the Carreau viscosity model to characterize the flow behavior. The experimental parameters were selected according to the Tg and phase equilibrium. The position of nucleation in the die was studied according to the simulation results via a computational fluid dynamics code (FLUENT).
Processing Glass-Filled Polyethylene on a Twin-Screw Injection Molding Extruder
David Bigio, Rajath Mudalamane, Yue Huang, Saeid Zerafati, May 2000
The mechanical properties of glass-fiber reinforced thermoplastics depends largely on the post-processing fiber length distribution. The traditional method of compounding in an extruder followed by injection molding causes considerable fiber attrition. In this study, the benefits of using a novel type of machine -the Twin-screw Injection Molding Machine (T.I.M.E.) - is investigated. The effects of operating conditions such as screw speed, glass-fiber content and extent of screw fill, on the final fiber lengths and distribution are studied. Optical microscopy and image analysis methods were used to analyze the processed parts.
Developing Animations and Simulators for Plastics Education
Kirk Cantor, May 2000
Instructional technology, computer-based training, and multimedia are a few of the modern words associated with the wave of technological advancement in educational methods. The plastics industry is not only riding this wave, but has been a contributor in leading these advancements. This paper describes the development of several projects that expand the body of technology-based plastics education. These projects include animations used to describe machinery or present difficult polymeric concepts and simulators used to teach operational techniques. Hardware, software, and methods used in these projects are discussed.
Cover Part as an Application Example for Gas-Assisted Injection Molded Parts
Michael Hansen, May 2000
The gas-assisted injection molding process is in use now for several years offering new technical and creative possibilities for injection molding. After a brief survey of the principle sequence of the process and basic process physics this paper comments on an application example for a cover part and provides solutions for the problem s found during the process of fixing existing issues on this tool.
Magnetic Resonance Imaging of Polymer Melt Flows
Yusuf Uludag, Michael J. McCarthy, Robert L. Powell, Geoffrey Barall, May 2000
A tubular rheometry that is based on obtaining velocity profiles by nuclear magnetic resonance imaging (NMRI) and measuring pressure drop of the flow is used for the polymer melts. This technique allows one to get viscosity data potentially over many decades of shear rate region in a single measurement. In this study, we examined polyethylene melt as the flow medium. Despite the low shear rates attained, our results reveal that this non-invasive and non-destructive method is promising for constructing an on-line polymer melt rheometer.
Relaxation Model for FE Analysis of Plastic Product Behavior
Ihor D. Skrypnyk, Jan L. Spoormaker, May 2000
The non-linear creep-based models cause numerical instabilities during FEA calculations because of the necessary inversion of stress-strain relations. From this point of view, the relaxation-based models are preferable for use within FEA. On the other hand, engineers avoid such models, due to complicated tests. Therefore, the goal was to develop the non-linear relaxation model, which uses the data of creep-recovery tests. In this way the model would be comparatively inexpensive and unconditionally stable in FE calculations.
Vibration Assisted Resin Transfer Moulding (VIARTM): A New Alternative Technique to Improve RTM Performance and Part Quality
Nikos G. Pantelelis, Athanasios Bikas, Andreas E. Kanarachos, May 2000
At the present paper a new system with the aim to improve the RTM process has been developed and presented. The system is based on the assistance of the resin flow with mould-inducing mechanical vibrations. Potential advantages of the proposed method are the improvement of the quality of the composite part (reduction of voids and reach areas), decrease of the filling time and/ or the maximum applied flow pressure. A test apparatus has been set up at NTUA to study the various mechanisms that relate the resin flow through the preform mat, the curing and the external vibrations. The project is progressing well and initial results are very promising and will be presented at the conference.
A Novel Ionomer for Nylon Modification
Richard T. Chou, May 2000
A new family of Surlyn® ionomers containing reactive functional groups is being developed for polymer modification, e.g., modifying nylon for blow-molding applications. Compared to existing ionomers, the new ionomers exhibit a higher degree of compatibility with nylon. One of the unique features of the new modifier is that the new ionomers can be dispersed in nylon in an extremely fine particle size and narrow size distribution. This has a profound effect on both the melt rheology and the mechanical properties of the modified nylon. Most significantly, the new ionomer imparts a truly shear thinning melt viscosity of the modified nylon 6. The paper discusses the dispersion of the new ionomer in nylon 6 as analyzed by SAXS and TEM and the melt rheology behavior of the modified nylon 6 and briefly highlights the effectiveness of the new ionomer to modify nylon 6 for the demanding blow-molding applications.
The Creep Behavior of Poly(ethylene terephthalate) Bottles
Prakash S. Sonti, Saleh A. Jabarin, Michael R. Cameron, May 2000
Room temperature viscoelastic behavior of PET beverage containers was studied. Internal pressures result in an increase of the container volume. By assuming a cylindrical geometry, stresses can be computed and linear strains can be estimated from the volumetric changes. A time-dependent creep compliance was determined for 2-L freestanding containers under various internal pressure loads. These values match favorably with uniaxial creep measurements. From isochronous plots, the viscoelastic behavior is shown to be linear over a limited range of pressures. The creep curves show all the characteristics of simple linear viscoelastic models such as instantaneous elastic response, retarded elastic response and permanent deformation.


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