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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Dispersed Solids Melting Model in Single Screw Extrusion
In opposite to most screw designs the geometry of some single screw concepts lead to a break-up of the so called solid bed. Therefore the well known Tadmor-Model is not capable to describe this melting behavior. First approaches for such a model were already made by several scientists. Unfortunately these models assuming some simplifications having a strong effect on the accuracy. Thus a new dispersed solids melting model was developed assuming less simplifications. It shows good agreement with experimental results.
Drawing of UHMWPE Fibers in the Presence of Supercritical CO2
The drawing behavior of UHMWPE fibers in supercritical CO2 is compared to that in air at different temperatures. Temperature substantially influences the drawing properties in air, while in scCO2 a constant mechanical response is observed. DSC and WAXS results show that air-drawn samples crystallize during deformation in an internally constrained manner, promoting changes in their thermal behavior. In contrast, scCO2 allows crystals to grow without constraints through a possible crystal-crystal transformation, increasing the processing temperature to 110°C.
The Effect of Aqueous Media on Creep of Recycled Plastics
There continues to be a need for additional uses of recycled plastics. A significant portion of recycling applications require outdoor exposure including use in aqueous applications. This paper covers the effects of water on the properties of recycled plastics under tensile loads. The paper also covers long term creep effects.
Effect of Cavitation on Product Cost
In today's industry, there is a constant debate over the methods used to meet production requirements. Using a single, high cavitation tool is often compared against using multiple low cavitation tools. There are numerous factors that must be considered when deciding on which tooling option to specify and its ultimate effect on part cost. The scope of this paper is to serve as an aid in the tool selection process by providing a step-by-step process that allows a company to make a well-informed decision on tooling layouts while considering the impact of each factor on part cost.
Effect of Gas-Transmission Property in Modified Atmosphere Packaging for Fresh Produce
Changes of gas concentrations inside a package were studied using several kinds of materials in Modified Atmosphere Packaging (MAP) for Fresh produce. Respiration rates of Shiitake mushroom as Fresh produce and gas-transmission rates of these materials were measured and predicted at various temperature.Changes of gas concentration inside a package were simulated using a Michaelis-Menten type equation model and material's gas transmission rates. Suitable packaging material in Modified Atmosphere Packaging was discussed from the viewpoint of it's gas-transmission rates."
Effect of Groove Geometry on the Performance of Grooved Feed Extruders
The effect of varying groove geometry on the solids conveying performance of a grooved feed extruder was evaluated. Three groove styles and two resins were evaluated on a single barrier screw design. The results indicate that groove geometry has a strong effect on extruder performance for HDPE but a negligible effect for LLDPE.
Effect of LCP Addition on the Properties of Hybrid Composites
A hybrid composite consisting of rubber toughened nylon 6,6, glass fiber and LCP was investigated by varying LCP content. The hybrid system exhibited better processability than the glass fiber reinforced composite. A decrease in the total torque was observed with the LCP content indicating the reduction in the energy consumed during the processing of the hybrid composites. Thermal stability of the glass fiber reinforced composites improved with LCP addition. SEM observation of the tensile fracture surface revealed LCP fibrillation in the toughened matrix.
The Effect of Moisture on the Rheological Behavior of Calenderable Copolyesters
The effect of absorbed moisture on the rheological behavior of a series of calenderable copolyester resins is studied. Moisture has a profound effect on the viscosity of the resins at calendering temperatures and on the glass transition temperature of the resins. However, moisture does not lead to hydrolysis of the copolyesters at the relatively low temperatures used in calendering.
Effect of Runner Design and Gating on Concetricity of High Precision Cylindrical Molded Parts
This paper presents a study on how shear induced melt variations, developed in runners, continue into a cavity and affect the shape of high precision cylindrically molded parts. Melt variations from the runner create asymmetrical conditions within the part forming cavities. These asymmetrical conditions can create side-to-side variations which effect concentricity in high precisions parts such as gears. Effects of process, gating locations and runner designs are presented.
Effect of Strain Rate on PVC Impact Performance
The impact behavior of poly(vinyl chloride) (PVC) siding formulations containing chlorinated polyethylene (CPE) and acrylic core-shell impact modifiers was evaluated using an instrumented impact tester. The samples were tested at room temperature over a range of testing speeds. Differences in strain rate sensitivity were observed for the various formulations. The differences appear to be a result of both the impact modifiers and the overall formulation.
Effect of Structural Relaxation on Dynamic Mechanical Properties of Poly(Methyl Methacrylate)
Mechanical spectra of atactic poly(methyl methacrylate) were measured via dynamic mechanical analysis. Measurements were taken on specimens annealed in the temperature range of 23 to 100°C for varying lengths of time. It was found that the effects of thermal treatment are more varied than previously reported, with significant differences found in the breadth and location of the ? and ? relaxation peaks.
Effect of the Mesh Number Elements in the Simulation Results of Normalized Test Specimens Injection Molded
The study was made by modifying the simulation mesh model characteristics to mold normalized test specimens. The simulation results were obtained through a filling/cooling simulation program for the injection molding process. The simulated filling time, optimum cycle time and injection pressure, seemed to be influence by the number of elements model. A best agreement between experimental and simulation results were obtained by increasing the number of elements of the mesh model.
Effect of Wall Slip of Polymer Melts on their Relaxation Modulus Behavior
The determination of the relaxation modulus using the step imposition of a strain is an important step in the fitting of the parameters of viscoelastic constitutive equation. In the nonlinear region the true shear strain imposed on a polyethylene melt is found to deviate considerably from the targeted strain due to the presence of wall slip which is documented here. The presence of the wall slip reduces the range of strains for which the strain-dependent relaxation modulus can be determined for the linear polyethylene melt investigated.
Effects of Additive and Polymer Architecture on Antiplasticization of Model Epoxy Networks
A new class of antiplasticizers is investigated for epoxy-based crosslinked polymers. In order to elucidate the mechanisms for antiplasticization of epoxy thermosets, effects of additive chemistry and network architecture are considered. Both model and commercial epoxy networks are studied, probing the effect of molecular weight between crosslinks. Additionally, the family of phosphates being studied ranges in molecular weight and density which are shown to strongly influence the degree of antiplasticization. Mechanisms of antiplasticization are discussed.
The Effects of Dynamic Vulcanization on the Morphology and Mechanical Property of Rubber/Plastic Blends
The effects of dynamic vulcanization on the morphology and mechanical properties of rubber/plastic blends are investigated. This study includes the discussion of why the mechanical properties differ before and after dynamic vulcanization. Enhanced interfacial adhesion by dynamic vulcanization was found to be a major contributor of superior tensile strength of TPV. Rubber elasticity of TPV is a result of the combined effects of crosslinked rubber, morphology, and amorphous PP phase plasticization.
The Effects of Extreme Stress during the Injection Process on Polypropylene
The strength and viscosity of polypropylene is influenced by extreme stress during the injection process. By varying backpressure of the material in extreme conditions the strength of the part will decrease. Reduced strength of the part will be proven through tensile and impact testing. Numerous material generations of polypropylene will be compared to virgin polypropylene to prove the decrease in strength.
Effects of Lubricants on Processing of Polymer-Wood Composites
A number of lubricants have been evaluated in polymer-wood composites. These lubricants have been evaluated in both HDPE-oak and HDPE-pine composites. Properties measured included extruder torque levels, outputs, extruder shear heating, and visual assessment of extruded part appearance.
The Effects of Machine Nozzle and Sprue Design in Mold Filling Imbalances
The imbalance between the cavities in a geometrically balanced, multi-cavity mold used for injection molding has previously been explained in theory as shear induced imbalances". (1) The cause of these imbalances can be from uneven shear effects on the melt as it travels to each cavity through the runner. This paper presents a study which finds that the machine nozzle and sprue can have a significant contribution to shear induced mold filling imbalance. The effect of geometry material and process are evaluated."
Effects of Nanocomposites on the Oxygen Barrier Properties of Polyethylene
The Permeability of polyethylene limits it's use in applications where oxygen barrier properties are required. Polyethylene, an extremely non-polar molecule, exhibits low permeation levels with polar substances such as water. Conversely, non-polar gasses such as oxygen exhibit high levels of permeation. A silicate nanocomposite was added to reduce the permeation of non-polar gasses while maintaining the low permeation of polar substances. The polyethylene nanocomposite provided better oxygen permeation properties than traditional grades of polyethylene.
Engineering and Specialty Plastics in the World 2000-2010
Out of total world plastics consumption currently over 150 million tons, engineering plastics amount to 6 million tons, specialty plastics to 200 000 tons. Overall value figures are much higher compared to volume figures.Engineering and specialty plastics have common characteristics:Higher performance properties than commodity plastics, higher temperature performancesConcentration of few world suppliers.Main applications in the car and electrical industriesFaster growth than commodity plasticsCompetition between commodity and engineering plastics.Some engineering plastics might achieve commodity volumes by 2010
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