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 Tetrabromooligocarbonate with Polycarbonate
James Y.J. Chung, Winfried Paul, May 2000
Tetrabromooligocarbonate (TBOC) was melt-blended with Bisphenol-A polycarbonate (PC) in various ratios to determine their miscibility with PC. According to the glass transition temperature (Tg) of the blend, TBOC can be miscible with PC, depending on the molecular weight of TBOC and its amount in the blend.
Joint Performance of Mechanical Fasteners under Dynamic Load
Axel Tome, Gottfried W. Ehrenstein, Frank Dratschmidt, May 2000
Threaded Inserts in either brass or plastic or rather economic self-tapping screws can be used to join different polymers or polymers to metal at high loads. Usually joints are subjected to dynamic loads as well as temperature variations. In this paper the static and dynamic load limits of mechanical fasteners (insert/self-tapping screw) will be discussed.
Application of Pulsed Electrochemical Machining to Micromold Fabrication
Blaine Lilly, May 2000
Pulsed electrochemical machining (PECM) is an effective method for removing EDM surface damage from tool steels, while maintaining the surface geometry to close tolerances. Mold steels show improved fatigue life after PECM when compared to steel machined by EDM. Because the tool does not wear during machining, PECM also shows promise as a method for machining micromolds. This paper reports on mold finishing research using PECM, and ongoing work applying the technology to micromachining of mold cavities.
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.
Influence of Thermal History and Molecular Weight on the Mechanical Properties of High Density Polyethylene
C. Albano, R. Sciamanna, G. Delgado, D. Kaiser, May 2000
Several variables affect the plastics solidification process, being the thermal history given to the polymer and its molecular weight the more important. Therefore, this paper is mainly aimed at establishing a relationship between thermal history, mechanical properties and molecular weight of HDPE based on mathematical models of the following type: mechanical property =f(molecular weight, crystallinity) through a multivariable non-linear regression method and three-dimensional views of the surfaces generated by the mathematical expressions were obtained to have a better view of the results and models developed, concluding that these models are very useful for the industry.
The Use of Thermomechanical Indices to Establish Straightforward Processing-Mechanical Properties Relationships
J.C. Viana, A.M. Cunha, N. Billon, May 2000
The thermomechanical environment imposed to the melt in injection molding is quantified by two thermomechanical indices estimated from computer simulations of the mould filling. These indices are associated to the onset conditions of the microstructure development, and aim at interpreting its final state. As the microstructure determines the mechanical properties, straightforward relationships between those and the thermomechanical indices can be obtained. In this work, axisymmetric specimens were injection molded with systematic variations on the melt and mold temperatures and the flow rate. The mechanical properties were assessed in tensile tests at cross-head velocities of 2, 10, 500 mm/min and 3 m/s. They were related to the thermomechanical indices. Their variations were interpreted in terms of the expectable microstructure of the moldings.
Rubbing Mechanisms of Polymers on Metal Surface Relevant to Extrusion
Hyun Seog Kim, Chan I. Chung, Thomas I. Butler, May 2000
The processing behavior of a polymer inside an extruder largely depends on the rubbing mechanism of the polymer on the metal surfaces of the barrel and the screw. The rubbing mechanisms of five commercial polymers were investigated from a metal temperature below the thermodynamic melting (or glass transition) range of each polymer to a metal temperature well above the melting range. The rubbing mechanism was found to depend on the polymer properties and the metal temperature. For rigid, amorphous or highly crystalline polymers, the rubbing mechanism is friction" at low metal temperatures below the melting range and "melting" at high metal temperatures above the melting range. For soft crystalline polymers with a broad melting range the rubbing mechanism is complex exhibiting "friction" "tearing" and "melting" as the metal temperature is increased."
Investigation of Crystalline Structure and Orientation of Polyamide 612 in Double Bubble Tubular Film Blowing Process
Sangkeun Rhee, James L. White, May 2000
Uni- or biaxially oriented polyamide 612 (=PA612) films were produced by a double bubble tubular film blowing process at a high extrusion temperature and with a rapid cooling of the first bubble films. The double bubble films stretched in a rubbery state were characterized using differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXS), small angle X-ray scattering (SAXS) and infrared (IR) spectroscopy. Biaxial orientation factors were computed with pole figure data and plotted in a White-Spruiell orientation triangle. DSC measurements showed that first bubble films exhibited a spontaneous increase in glass transition temperature (Tg), cold crystallization temperature (Tc) and crystallinity during aging at room condition (22 °C and 32 %RH). Highly biaxially stretched films had a well defined triclinic crystals when they are annealed in a boiling 20% formic acid solution or stretched at a high temperature. Structural parameters of crystals exhibited a big change with stretching conditions.
Structure Development in Biaxial Stretching of Cast Polyamide 11
Sangkeun Rhee, James L. White, May 2000
The development of crystallinity and polymer chain orientation in the biaxial stretching process of cast polyamide 11 (PA11) films was investigated. The characterization of the stretched films was done with birefringence measurements, wide angle X-ray diffraction (WAXS), differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS). Biaxial orientation factors were represented in a White-Spruiell orientation isosceles triangle. As distinct from polyamide 6 (PA6) and polyamide 612 (PA612), DSC scanning of as-cast PA11 film were crystalline and exhibited a little change in crystallinity by aging at room condition. The glass transition temperature (Tg) increased during aging. PA11 highly biaxially stretched in an elevated temperature had monoclinic and triclinic crystals, respectively. The dimensions of the crystals were changed with the stretching conditions.
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.
Block Copolymers as Templates for Functional Materials
Robert E. Cohen, May 2000
There are applications and devices which require controlled distribution of material functionality (electrical, optical, catalytic, magnetic) in two or three dimensions. At the nanometer length scale, attempts to meet this challenge have included template-mediated materials chemistry (Martin 1994) in which track-etched membranes, porous alumina and zeolites serve as the nanoscale reaction vessels for the synthesis of the functional materials. The ability to control both the length scale and the spatial organization of block copolymer morphologies makes these materials particularly attractive candidates for use as templates in the synthesis of functional nanocomposites. Appropriate choices of the repeat units of the block sequences renders them capable of selectivity sequestering preformed inorganic nanoclusters or selectively solubilizing inorganic reagents for in-situ cluster synthesis. Methods exist to produce nanoscale voids which percolate through the structure, leading to processes which coat or backfill the channels with functional materials. Electroless plating methodologies which have been used to apply surface of metals to polymer films can be adopted to produce metallic structures selectivity within block copolymer domains.
Tensile Properties of Linear Low Density Polyethylene (LLDPE) Blown Films
Rajendra K. Krishnaswamy, Mark J. Lamborn, May 2000
Various LLDPE resins that encompass those polymerized using Ziegler-Natta, metallocene and chromium oxide based catalysts were blown into film and their tensile properties were investigated in relation to molecular orientation. The direction-dependent (MD vs. TD) tensile properties were observed to be significantly different from those of isotropic polyethylene specimens of comparable density. These were explained in terms of orientation and lamellar organization features. Excellent correlation between Elmendorf tear and tensile yield characteristics added credibility to previous hypotheses that specimen stretching and its associated microstructural deformations plays a significant role in Elmendorf tear tests.
Blends of Metallocene Polyethylenes for Recycling of Xerographic Toners
Hui Tang, Charles L. Beatty, May 2000
This paper presents experimental results on the blends of metallocene polyethylenes (mPE) for recycling of xerographic toners by reactive extrusion. The experiments were carried out in a reactive twin screw extruder. The evaluation of the mechanical properties and morphology for different blend consist of black xerographic toners with mPE with and without compatibilization by reactive processing. It is rather surprised that the impact strength property is synergistic behavior. The impact strength and the modulus of elasticity of the blends using compatibilizer can be significantly improved. Morphology studies employed scanning electron microscopy (SEM) show that not only the domain size of the phase of black toner can be reduced but also the interfacial adhesion can be enhanced by proper compatibilizeation. Phase morphology and domain size indicate that efficient dispersion was obtained for the compatibilized system whereas the phase of black toner was agglomerated in the interfaces without compatibilization.
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.
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.
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.
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