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
Fatigue Behavior of Discontinuous Glass Fiber Reinforced Polypropylene
Mustafa Sezer, Ahmet Aran, May 2000
The fatigue properties and mechanism of 30% wt. short glass fiber reinforced chemically coupled and uncoupled polypropylenes were determined. Depending on the degree of damage, debondings effect the load transfer to the fibers. Final fracture occurs if the number of non-loaded fibers in one cross-section increases up to the critical value. When the fatigue data was presented as S-N curves, both materials have not showed any endurance limits. The microstructural mechanisms were discussed by help of SEM observations.
Numerical Simulation of Bi-Layer Extrusion Flow within a New Conical Extruder
Alp Sarioglu, Daniel Schläfli, André Luciani, Jan-Anders E. Månson, May 2000
In this study, the coextrusion flow in the die section of a new type of multi-layer extruder is determined. The prototype extruder used is based on a conical rotor-stator assembly. The extrusion of a range of individual layers of PEs was investigated. Numerical simulation, based on an axisymmetrical model of the assembly using an inelastic fluid model, was used to analyze the flow behavior.
Freeze-Thaw Durability of Composites for Civil Infrastructure
J. Haramis, K.N.E. Verghese, J.J. Lesko, May 2000
Freeze-thaw durability is a critical area that needs to be investigated prior to implementing composite material use in civil infrastructure. This work will examine the performance of pultruded vinylester/glass and epoxy/glass cross-ply laminates in different aging environments. Tensile test data encompassing strength, stiffness, and strain-to-failure on as-received" and moisture saturated material will be presented as well as saturation moisture uptake data. Discussion of continuing experimental work related to freeze-thaw cycling will also be addressed."
The Hydraulic Permeability of Dual Porosity Fibrous Preforms
B. Markicevic, T.D. Papathanasiou, May 2000
We present a computational analysis of viscous flow through arrays of fiber bundles using the Boundary Element Method (BEM) implemented on a multi-processor computer. Up to 700 individual fibers are included in each simulation. These are simple but not trivial models for fibrous preforms used in composites manufacturing - dual porosity systems characterized by different inter- and intra-tow porosities. The way these porosities affect the hydraulic permeability of a preform is currently unknown and is elucidated through our simulations. Numerical results are compared to analytical models. Through a large number of simulations we construct a master curve for the permeability of arrays of fiber bundles for various packing arrangements.
The Development of a Consumable Container for Built up Roofing Asphalt
Donn R. Vermilion, Jorge A. Marzari, May 2000
An injection molded container has been developed for built up roofing asphalt. The container is consumable in the roofer's kettle unlike the paper carton it supplants. The development of the container consisted of three elements. The first element was the development of a compound that could be injection molded, withstand filling with molten asphalt, and later melt completely in the roofer's kettle. The second element was the design of a container that met processing, cost and customer requirements. The third element was the development of a cost-effective injection molding process.
Minimizing Sandwich-Panel Warpage
James S. Griffing, May 2000
Honeycomb-cored composite sandwich panels are widely used in commercial airplane interiors. Sandwich-panel warpage can cause assembly difficulties and has been a deterrent to implementation of determinant assembly techniques. A series of statistical experiments were used to minimize sandwich-panel warpage on an airplane stowage-bin shell. Warpage was broken down into three components to facilitate analysis. Twist was shown to be influenced by prepreg orientation. Spring-in was affected by the presence of a decorative poly(vinyl fluoride) film; this effect was counteracted primarily by the addition of a ply of style-120 prepreg on the opposite side of the panel. The additional ply of 120 prepreg also helped to minimize bow.
Non-Isothermal, Non-Newtonian Analysis of Three Dimensional RTM/VARTM Processes Using HP-Adaptive Finite Element Method
Ravi Mayavaram, Mahender Reddy, May 2000
A numerical analysis of the RTM/VARTM processes using an hp-adaptive finite element method is presented in this paper. The constitutive behavior of the resin is modeled using the Carreau-Yasuda 5-parameter model with the WLF and the Arrhenius functions for describing the temperature dependence of the viscosity. In addition, the viscosity can also be read in as a tabular function of the effective shear rate and the temperature. The RTM process is modeled as a three-dimensional, two-phase flow of resin and air (weakly compressible fluid) using a modified Darcy's model. Examples demonstrating the role of SUPG smoothing, viscosity variation, vacuum conditions, and dynamic adaptivity are presented in this work.
Mechanochemical Alteration of Ethylene Copolymers via Solid-State Shear Pulverization (S3P)
Manisha Ganglani, Stephen H. Carr, John M. Torkelson, Klementina Khait, May 2000
Solid-State Shear Pulverization (S3P) is a novel process that uses mechanical energy to cause mechanochemical alteration of some of the polymer chains. The process pulverizes polymers and results in fine powders. Fragmentation events involve a limited amount of chain cleavage depending upon the levels of mechanical strain developed and the molecular weight distribution of the materials. Several virgin ethylene homo- and copolymers were used in this study. It is seen that S3P can alter the flow properties but leaves molecular weight distributions and the thermal properties of these polymers unchanged.
Investigation of the Mechanisms by Which Glass Fibers Disperse in a Polystyrene Matrix
Melody M.H. Kuroda, Chris E. Scott, May 2000
Effective dispersion of chopped glass fibers into thermoplastic matrices is critical for achieving optimum properties. In an effort to further understand the mechanisms by which dispersion occurs, model experiments are conducted using 4 mm long chopped glass fiber bundles embedded in polystyrene. The effects of the process variables of temperature and shear rate upon the onset and mechanism of dispersion are investigated with optical microscopy. Two distinct breakup mechanisms can be identified: rupture and erosion. Rupture results in clusters of fibers separating from the bundle. Erosion occurs when single fibers are removed from a bundle's edge. The onset of dispersion in both simple shear and squeezing flow experiments is a stochastic process.
Laser Surface Modification of Polymers to Enhance Adhesion Part II-PEEK, APC-2, LCP and PA
S.M. Tavakoli, S.T. Riches, May 2000
Excimer lasers have been employed to modify the surfaces of a range of polymers to enhance adhesion. Considerable increases in joint strength were achieved as a result of laser treatment. Many lap shear joints, exposed to hot/wet environments, provided high retention of joint strength and durability. Laser-treated PEEK and APC-2 joints exposed at 50°C and 96%RH for several weeks, showed excellent resistance to ageing.
Stereolithography Inserts - Pros" and "Cons" to Use Tin as a Backfilling Material"
Aureo Campos Ferreira, Carlos Henrique Ahrens, Fernando Humel Lafratta, Ricardo Borges Gomide, May 2000
Stereolithography inserts shells for injection molding tools are filled in the backside, aiming to support high pressures and to improve the cooling efficiency on the mold. A common backfilling material used is an alloy of bismuth. However, there are other alternatives, such as tin, which has a higher thermal conductivity. This article discusses the pros" and "cons" to use tin as a backfill and investigates if it provides a better cooling condition improving mold's life."
Enhancement of Natural Fiber-Epoxy Interaction Using Bi-Functional Surface Modifiers
Arun Sampath, George C. Martin, May 2000
Enhancement of fiber-matrix interaction for a jute-epoxy composite system was attempted by surface modification of the fibers. The surface modification of jute fibers was achieved using bi-functional amines, which were capable of bonding with both the fiber and the matrix. The changes in interface bonding were observed by measuring the flexure modulus of the composite samples.
Ethylene/?-Olefin Elastomer Based Compositions for Automotive Interior Applications
Kim L. Walton, Tim Clayfield, May 2000
Ethylene/alpha-olefin copolymer elastomers based on single site constrained geometry catalysts exhibit a number of physical properties that make them extremely useful for automotive interior applications. Due to the low level of unsaturation in these polymers, they exhibit outstanding heat and UV aging resistance. Their molecular structures enable these polymers to exhibit low glass transition temperatures (Tg). Thus, compositions containing these polymers exhibit very good low temperature impact properties. Furthermore, these products impart inherent flexibility and soft touch to compositions and eliminate the need for plasticizers. Ethylene/1-octene copolymers exhibit an optimum combination of ultimate tensile and low temperature properties. Ethylene/1-octene copolymers can be compounded to produce flexible TPO compositions with elevated temperature and desirable softness suitable for automotive interior applications.
Utilisation of Fly Ash as a Filler in Plastics
Maurice Biagini, Alexandre Paris, Jesse McDaniel, Vaclav Kovac, May 2000
Fly ash is a by-product of the ground coal burning process used in power generation plants. Since fly ash primarily consists of inorganic materials, it is a potential filler substitute for conventional fillers in the plastic industry. In this work, the mechanical, physical, and thermal properties of fly ash filled polypropylene were determined and the effect of adding fly ash on the properties of the resin was studied. Driven by the economical potential and environmental aspect of the usage of fly ash, this study enabled us to determine the viability of coal fly ash to be used as a substitute filler in plastic resins.
Biologically Derived Conducting Plastics
Wei Liu, Jayant Kumar, Sukant Tripathy, Lynne Samuelson, May 2000
A new biological strategy has been developed to synthesize water-soluble conducting polyaniline. In this approach, anilines are polymerized by the enzyme horse-radish peroxidase (HRP) catalysis in aqueous buffer solution at pH 4.3 in the presence of a template. Strong acid polyelectrolytes such as polystyrene sulfonate (SPS) and the aqueous micelles formed by strong acid surfactants such as dodecylbenzenesulfonic acid (SDBS) are favor-able templates to form nano-scale reactors for the growth of conducting polyaniline. The properties of this enzymatically synthesized polyaniline are consistent with the polyaniline that is traditionally prepared via either chemical or electrochemical procedures. This biological approach offers unsurpassed ease of synthesis, processability, stability (electrical and chemical), and environmental compatibility.
Development of a Reactive Extrusion Process for the Production of Plasticized Film Grade Polylactic Acid
Rodney K. Williams, Scott R. Koenig, May 2000
The development of a reactive compounding process to provide an economical route for the production of film grade polylactic acid is discussed. The development of this process required the synchronization of a large number of unit operations. The unit operations were combined in a manner to optimize throughput and devolatilization, while minimizing gel formations and blocking. Free radical branching, plasticization, devolatilization, underwater pelletization and surface treatment techniques were employed during the development process. Process development was accomplished on a co-rotating, intermeshing twin screw extruder equipped with both devolatilization and underwater pelletizing systems.
Product Fabrication Project/Course
J.-M. Charrier, May 2000
Polymer engineering courses are now being taught in a variety of departments of numerous engineering schools all over the world. In many cases, a single introductory course is offered, sometimes shared by departments. A practically-oriented project, designed to alert the students to the strong interdisciplinary nature of the field and to prepare them for the type of work that many engineers do in this field, will be discussed in the light of over thirty years of experience in our school. The project can be integrated in an introductory polymer engineering course or, in an expanded form, made into a complementary course. The presentation will include the general objectives, as well as many practical considerations which are important to the success of such project or course.
Effects on Mechanical Properties of LLDPE after Modification with Organic Peroxides
Luis Mendes, Joao D'Alessandro, Ailton Gomes, Marly Lachtermacher, May 2000
The action of two differents organic peroxides at 290°C on the mechanical properties of linear low density polyethylene (LLDPE) viewing its application as internal pipeline coating was studied. When the amount of crosslinking agent increased on polyolefin it was observed that for both peroxides a decreasing of elastic modulus and stress at yield. The stress at break raised and the drop of elongation at break cocurred from 0,5% of peroxide.
Polyethylene Synthesis Using Zeolites as Support Material for Metallocene Catalysts
Simone C. Moreira, Maria de Fátima V. Marques, May 2000
In the synthesis of polyethylene, sodic mordenite and acid ZSM-5 zeolites were evaluated as support material for bis (cyclopentadienyl) zirconium dichloride catalyst system. The zeolites were calcinated at 300°C before treatment with methylaluminoxane (MAO) and Cp2ZrCl2. The supported catalyst systems were evaluated in terms of polymerization activities by varying the temperature of Cp2ZrCl2 impregnation on the support and the MAO and Cp2ZrCl2 concentrations.
Properties of an Oil Resistant TPV
S. Cook, J. Patel, A.J. Tinker, May 2000
A TPV based on a dynamically vulcanized blend of epoxidized natural rubber and polypropylene is described. Morphological and rheological properties are briefly reviewed. Basic physical properties compare well with those of other TPVs whilst oil resistance is comparable to that of a well-compounded NBR vulcanizate (34% acrylonitrile). Excellent heat resistance with good retention of properties on ageing for extended periods at 100° and 150°C is also demonstrated as is good weathering and ozone resistance.
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