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
Blends of Poly(ethene-co-octene) Elastomers
Hui Tang, Charles L. Beatty, May 2000
Blends of polystyrene (PS), and polymethyl methacrylate (PMMA) with poly(ethene-co-octene) elastomer (POE) were investigated. The experiments were performed in a counter-rotating reactive twin screw extruder. The evaluation of mechanical properties and morphology were completed to determine stress-strain behavior, impact, domain size, and interfacial adhesion for the blends. The results of tensile strength, modulus of elasticity, and impact properties for the blends show that incompatible and synergistic behavior over a wide range. Morphology studies using scanning electron microscopy (SEM) indicate that the domain sizes of rubber phase in the blends are rang from 1 to 15 ?m and a variety of interfacial adhesion behavior. All the blends displayed phase-separated. The blends of polystyrene / poly(ethene-co-octene) elastomer with compatibilization illustrate that not only the domain size of the phase of elastomer can be reduced but also the interfacial adhesion can be enhanced. The mechanical properties of the blends using compatibilization , such as impact strength and tensile strength, can be improved.
Understanding Color Technology
Scott A. McCabe, May 2000
The production of custom colored thermoplastic elastomers often involves the use of color concentrates provided by a color house. In order to effectively communicate color requirements, a good understanding of the principles of color technology is a necessity. The basic principles of color theory will be discussed and current industrial practices of measuring color will be presented. Proper selection of color tolerances will be illustrated with several case studies.
Investigation of the Melting Mechanism within a Groove-Feed Single-Screw Extruder
Michael R. Thompson, John P. Christiano, May 2000
The melting mechanism of LLDPE in a groove-feed extruder was studied through crash-cooling the machine and examining the solidified polymer on the screw. The solids-conveying angle appeared as high as 70° near the end of the grooves, reducing to the helix angle of the flight within the melting zone of the screw. Melting was dependent on the dissipated mechanical energy derived from the high internal friction within the solid bed and solids deformation whilst in the grooved feed section.
A New Barrier Screw Design Utilizing Solid Bed Deformation with Forced Melt Removal
John P. Christiano, Michael R. Thompson, May 2000
A new patent pending barrier screw geometry incorporating modifications to the solids channel of the barrier section of the screw was introduced to improve melting and mixing efficiency. The new design geometry repeatedly deforms the solid bed to improve melting and mixing. Cross channel pressure gradients and screw pull-outs obtained from crash cooling experiments were used to investigate the working principles of the new design. The results were compared to those obtained under similar conditions with a conventional barrier screw.
Towards Design Guidelines for Injection Molded Biodegradable Plastics Products
Prabhu Kandachar, Rolf Koster, May 2000
Specimens of two semicrystalline biodegradable thermoplastics, polyester-amide and polyhydroxybutyrate, injection molded at various settings, have been tensile tested. Upper limits to wall thicknesses with respect to surface appearance were found less severe than for traditional plastics. Molding settings appeared important for mechanical behavior. A higher degree of crystallization was obtained for polyhydroxybutyrate when the cooling rate was decreased. The lowest possible mold fill pressures appeared preferable, increasing ductility for both materials.
Melt Temperature Considerations for Extrusion
Edward Steward, May 2000
Melt temperature measurement and control are important to understand when optimizing or studying extrusion systems. This extrusion parameter is not as simple to measure as it may seem. This discussion will include the devices that are typically used for the measurement and control of melt temperature and the methods of employing the devices to get meaningful results. Accurately knowing the melt temperature level of a given system allows an accurate comparator for possible improved equipment design. Adjusting melt temperature via altering machine parameters for optimized extrusion results requires that the measured value is a meaningful number. A general discussion of melt temperature in extrusion will be carried out for this tutorial and the measurement and control of this important parameter will be discussed.
Polydiacetelene Fiber Optic Pressure Sensors
M. Tabib-Azar, S. Angkaew, J. Lando, May 2000
Micro-opto-electro-mechanical sensors (MOEMS), where optics are integrated with micro-electro-mechanical systems (MEMS), are logical candidates for sensing flow, temperature and pressure in harsh environments. MOEMS offers small size, high frequency response, immunity to electromagnetic interference, and resistance to degradation from exposure to harsh environments. However, interfacing MEMS with fiber optics is quite challenging. Here we discuss the possibility of coating the fiber with a pressure sensitive polymer (polydiacetelene) to increase its coupling strength to a MEMS' deformable diaphragm. Interestingly, we noticed that the coated fiber, in this case, was itself sensitive to hydrostatic pressure and could be directly used as a pressure sensor. The sensitivity, reproducibility and the structure of this simple and inexpensive structure are discussed in this work.
Fiber-Optic Electric Field Sensors Using Polymer-Dispersed Liquid Crystal Coatings and Evanescent-Field Interactions
M. Tabib-Azar, B. Sutapun, T. Srikhirin, J. Lando, May 2000
A simple evanescent-field fiber- optic electric-field sensor is reported. The sensor is constructed by coating the exposed fiber-optic core with a polymer-dispersed liquid crystal (PDLC). The effective refractive index of the liquid-crystal polymeric coating [poly(methyl methacrylate)(PMMA)/E7] has a large dependence on the direction and the magnitude of an any electric field present. This dependence was large enough to enable simple transmission measurements to detect the presence of an applied electric field. By coating a PDLC film onto the exposed core of the optical fibers, we are able to detect an electric field. The sensors showed good sensitivity and reproducibility and a polarity dependence was observed. The time response of the device is dominated by the RC time constant of the structure rather than the response of the PDLC and is approximately 3 minutes with 15-20 minute relaxation time. Using an electric circuit model of the device we also discuss how these response times can be improved by many orders of magnitude.
The Effect of Molecular Structure on the Extensional Melt Rheology of Conventional and Metallocene Polyethylenes
Choon K. Chai, May 2000
Extensional melt rheology and processing characteristics of conventional high pressure low density polyethylene (LDPE) and Ziegler-Natta linear low density polyethylenes (LLDPE) are compared with both narrow and broad molecular weight distribution (MWD), long chain branched (LCB) metallocene polyethylenes. The effects of MWD and LCB on the melt behaviour of these different types of polymers will be presented in terms of their dynamic linear viscosities and their strain-hardening behaviour from transient tensile stress growth experiments. Film processability properties will also be discussed.
Method to Estimate Vibration Behavior of Fiber Reinforced Thermoplastic Parts
Takahisa Yasuzawa, Yoshinori Kanetoh, Teruo Tachibana, May 2000
Until now it has been difficult to estimate quantitatively the vibration behavior of FRTP parts using computer simulation. The reason was that the conventional simulation model did not express appropriately the damping properties of vibration (dependence on the temperature, amplitude, frequency and moisture content) and the orthotropic Young's modulus. Therefore, a new simulation model was proposed through measuring the damping factor of the specimen and the experimental modal analysis of the parts. Based on this model, the simulation result of the realistic vibration behavior on the FR-nylon product (e.g. air intake manifold) proved to be in good agreement with the experiment.
A Novel Gas Driven Dual Barrel Capillary Rheometer
A. Goettfert, May 2000
A new capillary rheometer has been developed which is gas driven using a high-precision pressure controller. The flow rate is determined on-line. A precision pressure transducer controls the applied pressure to a maximum 21 MPa with an accuracy of better than 0.1%. The rheometer described here has a twin barrel system. Due to the equilibrium N2-pressure control in both barrels, creep tests can be performed, applying constant pressure irrespective of the installed die geometry. The flow rate from each barrel is independently measured.
Flow Surging in Single-Screw, Plasticating Extruders
Mark A. Spalding, Joseph R. Powers, Phillip A. Wagner, Kun Sup Hyun, May 2000
Flow surging in single-screw, plasticating extruders is the variation of the machine's rate with time, and it generally leads to higher production costs, lost production, and often higher scrap rates. Flow surging can originate from many different sources including machine controls, resin feedstock variation, screw geometry, and machine temperature. This paper will focus on flow surging that originates from improper solids conveying, and it will present experimental data and corrective action to eliminate or minimize surging.
CAE Approach to Relieve Notebook Connector Air-Trap Problems
Rong-Yeu Chang, Alice S. Lin, David C. Hsu, Fu-Ming Hsu, May 2000
Air trap problem is crucial to notebook connectors that have complicated rib-hole structure and thickness variation. Engineering experience is usually not enough to provide a suitable gate-runner system design for these intricate parts. In this work, various design proposals are examined via mold filling simulation in order to avoid potential air-trap and void problems. This approach is proved to be effective to notebook connector mold designer for verifying design on computer before mold is constructed.
Crystalline Transitions in Nylon/Clay Nanocomposites
Tzong-Ming Wu, Chein-Shiun Liao, May 2000
Nylon 6-clay hybrid is a molecular composite of Nylon 6 and uniformly dispersed silicate monolayers of synthesized saponite. Nylon 6 has two crystalline forms, ? and ?. The a phase is the thermodynamically most stable crystalline form but the ? phase is not. In this study, the nylon 6/synthesized saponite has prepared by the intercalation of e-caprolactam and then exfoliating the layered synthetic saponite by subsequent polymerization. The DSC thermal analysis and X-ray diffraction methods were used to investigate the crystal structure change of nylon 6/synthesized saponite. The results indicate the presence of crystalline transition in nylon 6 nanocomposites. The effect of thermal annealing on the crystalline structure of nylon 6 nanocomposites in the range between Tg and Tm is also discussed.
Characterization of the Interfacial Regions in Multilayer Coatings by NEXAFS Microscopy
Carl G. Zimba, Harald Ade, A.P. Smith, May 2000
Characterization of polymer interfaces is an important analytical need in many areas of technology. Many techniques, that provide the requisite spatial resolution, provide limited quantitative chemical information. On the other hand, techniques, that provide the desired level of quantitative chemical information, have limited spatial resolution. A relatively new analytical tool, Near-Edge X-ray Absorption Fine Structure (NEXAFS) microscopy [1- 4], provides a unique combination of chemical specificity and spatial resolution that is particularly well-suited for characterization of interfaces in polymer coating, blends and composites. In this paper, the application of NEXAFS microscopy to a multilayer polymer coating is discussed.
Rheological and Blown Film Characterization of Binary Blends of Metallocene-Catalyzed LLDPEs
Rajendra K. Krishnaswamy, David C. Rohlfing, Bryan E. Hauger, May 2000
The advent of metallocene catalyst technology has created several opportunities in the worldwide packaging film marketplace. In this work, we explore the effects of blending two metallocene-catalyzed LLDPEs of reasonably differing molecular weights. Specifically, the shear rheology, quiescent and shear-induced crystallization characteristics, and blown film performance were investigated as a function of blend composition. The presence of small amounts of longer molecules was found to have significant effects on the shear-induced crystallization kinetics and blown film orientation of the blends; this was explained in terms of an increasing number of extended chain nuclei for crystallization with increasing molecular weight. Lastly, the biaxial orientation features in the crystalline and non-crystalline phases of the blend blown films were also characterized and used in explaining the Elmendorf tear and dart impact performance of the blown films.
High Performance Rigid Flexible Combinations Made of Thermoplastic and Liquid Silicone Rubber
S. Boßhammer, E. Henze, May 2000
The injection molding of LSR represents a cost-efficient process for the production of high quality rubber parts for technical applications. Due to excellent material properties at extreme temperatures silicone rubbers offer various advantages for the production of soft/rigid combinations in comparison to thermoplastic elastomers. A new kind of LSR is presented which exhibits excellent adhesion properties to engineering thermoplastics. The process and the adhesion mechanism is designed in a way that no mold coating is required. A systematic analysis of the injection molding process points out suitable material combinations and indicates the influence of process parameters on adhesion strength.
Simulation of the Filling and Curing Phase in Injection Molding of Liquid Silicone Rubber (LSR)
E. Haberstroh, W. Michaeli, E. Henze, May 2000
The injection molding of Liquid Silicone Rubber (LSR) represents a cost-efficient process for the production of high quality rubber parts. Due to the extreme thermal conditions in the mold and the very low material viscosity a precise subvolumetric filling of the cavity is required to avoid flash formation. Modeling flow properties, curing characteristics and as the pvT-behavior creates the basis for an unified simulation of the injection molding process. The implementation of these models into a process simulation software makes it possible to calculate the filling phase considering a subvolumetric filling and to simulate the course of cavity pressure during the heating phase.
Improvement of Pentium-II Connector Support Design by CAE Tool
Thomas Hsieh, David C. Hsu, Alice S. Lin, Andy G. Day, Rong-Yeu Chang, May 2000
Weld line problem is crucial to a Pentium-II connector support part on appearance and mechanical consideration. In this work, a CAE tool is adopted during the product-development in order to detect potential weld line problem of the design. Various design revisions are proposed and tried on the computer. This approach is proved to be cost-and-time-effective to shorten time-to-marketing and avoid molding problem by improving design in advance.
In-Situ Production of Electrically Conductive Fibres in Polyaniline-SBS Blends
R.H. Cruz-Estrada, M.J. Folkes, May 2000
Electrically conductive polyaniline (PANI) was thermally blended with polystyrene-polybutadiene-polystyrene (SBS) at different weight compositions. The resultant blends were capillary extruded in order to generate a drawing process in the PANI. Microscopic analysis of the extrudates revealed that the PANI was deformed during the process to produce elongated structures. Electrical measurements showed the relationship between the electrical conductivity and the weight fraction of PANI in the blends.
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