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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Structural Mechanics of Polymer Coated Optical Glass Fibers: Review
The paper contains a brief review of the state-of-the-art in the stress-strain analysis (Structural Mechanics) of polymer coated optical glass fibers, with an emphasis on the analytical modeling.
Kinetics of Isothermal Crystallization of Syndiotactic Polypropylene: Avrami and Urbanovici-Segal Analyses
In this paper, the Avrami and Urbanovici-Segal macrokinetic models were applied to describe the kinetics of isothermal crystallization from the melt state of syndiotactic polypropylene (sPP). Data analysis was carried out using a direct data-fitting procedure, in which the experimental data were directly fitted to each macrokinetic model using a non-linear multi-variable regression program. The results suggested that the Urbanovici-Segal model was the better of the two in describing the isothermal crystallization data of sPP.
Production of Structures from Thermoplastic Composite Towpregs
An efficient and cost effective way of producing continuous fibre-thermoplastic matrix composites relies on the use of towpregs. Equipments are being developed for the production of the towpregs and also to manufacture pultruded profiles and filament winding structures. The properties of the composite products are determined and compared with conventional alternatives. An assessment is made on the influence of the processing conditions on the output and mechanical properties of glass fibre/polypropylene (GF/PP) composites.
Friction Properties of Thermoplastics in Injection Molding
In the ejection stage of parts injection molded over cores the knowledge of the friction properties between the mould surface and the part are important to optimize the ejection system solution. The coefficient of friction depends strongly on the mould surface and the temperature at the moment of ejection. Prototype equipment was developed to measure the friction properties in as-molding conditions, and methods developed to perform the testing. Data will be presented for two thermoplastics (polycarbonate and polypropylene).
Prediction of Ejection Forces in Tubular Moldings in Amorphous Polymers
The prediction of ejection forces in tubular moldings (pipe fittings, cups, ..) is relevant for the optimization of the ejection systems in molds. An instrumented mold (pressure, temperature and force) for a tubular part was developed for measuring the actual ejection forces for two amorphous materials, polystyrene and polycarbonate. The ejection forces depend mostly on the holding pressure and the mould core temperature. The experimental data is used to validate a thermo-mechanical model that predicts the shrinkage and internal stresses.
Niche Marketing: High Temperature Nylons
As nylons 66 and 6 continue to grow in volume, they are beginning to take on the attributes of commodities, e.g., product interchangeability and price sensitivity. Producers are finding that high temperature nylons aimed at niche markets are sufficiently differentiated that they resist the trend toward commoditization while offering interesting volume potential in applications where value means more than price. This is an area where monomers make the difference and integrated producers have the field to themselves.
Fabrication of Quasi-Isotropic Laminated Films from Oriented LLDPE Film Using a Novel Supercritical CO2 Solvent Welding Technique
Supercritical Carbon Dioxide (SC CO2) is used as a reversible plasticizing agent to promote solvent welding in highly oriented LLDPE films. Films are stacked in a quasi-isotropic fashion to enhance film properties in all directions. It is shown that, after processing, the oriented morphology and crystallinity are unchanged. The strength of the laminate interface is tested. Tensile properties of the laminated film are evaluated and tear resistance is measured using a single specimen J1C.
Molecular Fortification of Crosslinked Networks
In this study, a small molecular phosphonate, dimethyl methyl phosphonate (DMMP), is investigated for its fortifier properties in addition to its diluent effects, using mechanical and thermal analysis techniques. This fortification is consistent with previously reported antiplasticization effects without the need for stiff, aromatic functionalities. Phosphonates are likewise known to enhance the flammability properties of polymers by reducing the heat release rate, resulting in a multi-functional additive.
Treatment of Hydronic Heating Hose with Additives in the Field
Radiant heating by circulation of fluid through hose in or beneath flooring has become popular because of cost efficiency, particularly in new construction. Many systems in the field have been operated above recommended temperatures or used poor choices of circulating fluid and, as a result, show degradative effects and crack initiation. An additive package was developed that largely reversed these effects as indicated by dynamic mechanical measurements of elastic modulus.
Melt Index from a Single Pellet
The melt index of a single pellet is measured by combining experimental viscosity determination and simple modeling of the flow in the melt indexer. Special parallel plates are used to quantify the shear rheology of a 5 mg sample, the viscosity data is fit to a Power Law model, and the melt index is calculated. Results from this technique are compared to the results from actual melt index measurements for polyethylenes with a range of melt index values.
Effect of Die Geometry on the Orientation of the Velocity Field during Bi-Layer Extrusion with a Conical Extruder
In this study, coextrusion flow in a new type of multi-layer extruder is analyzed by means of numerical simulation. This prototype extruder is based on a conical rotor-stator assembly. The extrusion of a range of polyethylenes and polypropylenes was investigated at various rotor speed regimes. The effect of die design and viscosity ratio between adjacent layers on the helicoidal flow is discussed.
The Secrets of Building Brand Loyalty and Customer Retention to Grow Profits by 10-15%
With it being widely recognized and accepted that by raising customer retention rates by as little as 5%, benefits far beyond the obvious can be gleaned from repeat customers. Learn how companies are making efforts to develop brand loyalty and prospering while those that aren't are missing out on growth and profit opportunities.
Optimized Mechanical Performance of Welded and Molded Butt Joints: Part I-Similarities and Differences
Recent developments were oriented on the analysis of the mechanical performance at local (knit lines and welds) and bulk (molded part) areas, with the influence of molding and welding conditions. It has been found that for non-reinforced and reinforced nylon, the mechanical performance in the knit planes and welded areas are approximately equal to the mechanical performance of a base resin (matrix). The observations on similarities and differences in the formation of knit and weld lines are presented in Part I of this paper.
Processing of Fine-Dispersed ZnO/PET Compounds Using Twin Screw Extruder
By using twin screw extruder, the compounding of PET, ZnO, and a modified polyolefin wax was carried out. As a result, the surface of ZnO was covered by a modified polyolefin wax, and, consequently, a fine-dispersed ZnO/PET compound was obtained without affecting the photocatalystic activity of ZnO. The plate, injection molded in 2mm thickness using this compound, had a good clarity and enabled to absorb the light of wavelength of under 360nm, completely.
Binary Blends of EVA and Metallocene-Catalyzed Ethylene-A-Olefin Copolymers for Film Applications
Blends of Ethylene-Vinyl-Acetate copolymers (EVA) with metallocene based ethylene-a-olefin copolymers have been studied, with the purpose of exploring their properties and potential in film packaging applications. The effect of blend composition on rheological properties, heat seal, optical and tensile properties has been examined. It is shown that depending on their composition, these blends can offer a good balance of properties and processability.
Modeling of Shrinkage and Densification of Powder Compacts
A previously proposed model for the densification of powder compacts under isothermal conditions is extended to provide predictions of shrinkage and non-isothermal densification. This model, combined with predictions of bubble dissolution under non-isothermal conditions can provide a complete description of the shrinkage and densification of powder compacts. Model predictions compare favorably with experimental results.
Falling Weight Impact Testing Analysis of Rotationally Moulded Polyethylene
The falling weight impact test is a common method to evaluate mechanical properties of rotomoulded parts. This is because the resistance to impact of rotationally moulded articles is very sensitive to variations in resin, processing conditions, etc. More information could be obtained from an instrumented falling weight impact test, such as impact force/time and failure mode variation. In this work, these relationships are studied. Also, the effects of material properties, processing parameters, such as temperature and introducing pressure, are discussed.
Investigations for the Numerical Determination of the TTT-Diagram for Unsaturated Polyester Resin Systems
During cure of a thermoset resin, the material exhibits three distinct phases: liquid, gel, and solid. Each of these material states is marked by dramatic changes in the thermomechanical properties of the resin. The glass transition temperature and the elastic modulus of the thermoset materials are two examples of the material properties that are of great interest to processors in the thermoset resin industry. The ability to predict the progression can give insight into the performance and optimisation of processing methods for thermoset resins.
Case Studies of Failure of Polymeric Electrical Insulation
Polymeric electrical insulation failures are due primarily to material composition, design, processing, service conditions or combinations thereof. Time to failure may be immediate, i.e., as manufactured, if specifications are not met. Others may not develop until after many years of service. Since life expectancy of electrical insulation is of the order of 40 years, failure in less time is considered unacceptable. Examples are given of many types of failure and their prevention for power distribution cable and for lower voltage applications.
Extrusion Visualization - From Blend Structure to Sharkskin
Over the last five years, we have developed optical technologies for in-line monitoring of extrusion. We review two areas where we have succeeded in uncovering important concepts and phenomena by shedding light on processes that were previously unobservable. In the area of polymer blends, we have made real-time observations of blend microstructure during extrusion. we found conditions by which droplets could align in the vorticity axis. In the area of sharkskin and polyolefin extrusion, we have visualized how polymer process additives act and what causes sharkskin.
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