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.
We examined a low cost technology for perpendicular magnetic patterned media that uses a metallic nanostamper and injection molding process. In this paper, we focused on the analysis of injection molding with passive heating, where the replication of 50 nm nanopillar arrays was successful. The effect of the thermal insulation layer on the replication quality was examined by analytical and experimental methods. Finally, the properties of magnetic layer deposited on the injection molded nanopillar array were analyzed.
Sulfonated polystyrene ionomers (alkali metal salts) with molecular weight below the entanglement molecular weight of polystyrene were prepared. The rheological behavior of the ionomers was characterized by dynamic and steady-state shear experiments. In general, the viscosity of the ionomers increased with sulfonation level and as the size of the cation decreased. Whereas, the starting polystyrenes were Newtonian fluids, the ionomers were non-Newtonian and viscoelastic.
A range of polyurethanes (PU) based on methylene diphenyl diisocyanate and polyether polyols varying in molecular mass, backbone structure and functionality are studied. Examination of the kinetic parameters of the PU reactions shows that the curing behavior and the hardness of such complex PU systems do not follow simple mixing rules. Scaling relationships to describe these complex dependencies and basic guidelines for formulation and processing are developed. Limitations of using the OHindex to predict the polyol reactivity are also discussed.
The flow patterns and injection pressures predicted using injection molding simulation software and actual flow patterns and injection pressures of the molded parts using a short study were compared and quantified. A method of validation was developed to compare the simulation results with actual molded parts and indicated that by using the correct combination of mesh type and certain process settings in the simulation software, an accurate prediction can be achieved with the simulation.
Flexural creep behavior of nylon 6/6 based long fiber thermoplastics (LFT) was determined using transient and dynamic testing methods. While the effect of increasing fiber volume fraction reduced creep, there was only a negligible effect of flow orientation effect. The creep data generated by dynamic mechanical analysis (DMA) tests was consistent with the transient tests.
Optically transparent nanocomposites were prepared via twin-screw extrusion of a medical-grade flexible PVC resin and an organically modified montmorillonite. Intercalation and orientation of the montmorillonite layers were observed via x-ray diffraction. A positive influence on barrier properties was noted, including a five-fold increase in oxygen barrier at minimal clay loading. Consistent with the literature, no significant changes in thermal stability in air were observed.
Porous polyester thermoset xerogels have been produced via sol-gel chemistry. The pore structure of these materials is tunable and can be altered independent of or in tandem with alterations in composition by adjusting solvent quality, solids content, and processing methodology. Cytocompatibility studies on selected xerogels imply effects of both pore size and materials chemistry, with fully aliphatic polyesters with large pore structures allowing for the growth of mammalian cells.
This paper undertook a numerical study to characterize expansion of extruded polystyrene foam blown with CO2. The effects of processing parameters on foam expansion outside filamentary extrusion dies were examined. Efforts were made to optimize the processing parameters for the achievement of highly expanded foams.
Based on the fusion behaviors of PVC, the influence of compounding route of PVC/Montmorillonite nanocomposites, on their properties, including flexural, tensile, dispersion, and morphology was studied. The experimental results indicate that both the extent of property improvement and dispersion of nanaoparticles in PVC/Montmorillonite nanocomposites are strongly influenced by the degree of gelation achieved in PVC compounds during processing.
Polyurethane elastomers were synthesized with ethylene glycol as chain extender. The macrodiol was poly(ethylene adipate) MW = 2000 ± 50. Two isocyanates were employed: 4,4- diphenylmethane diisocyanate (MDI) and 4,4’ - dibenzyl diisocyanate (DBDI), alone or as mixtures. Materials were characterized by DMA, DSC and WAXS. Changes induced by varying the type and the number of isocyanates and the order of their introduction were followed. Crystallinity was strongly reduced when DBDI was mixed with MDI.
The interfacial adhesive strength between hydroxyapatite (HAP) and poly(?-caprolactone) (PCL) were determined using T-peel tests. Their composite fracture toughness was determined using essential work of fracture concept. Electrospinning techniques were employed to obtain nanometer scale PCL fibers with and without HAP reinforcements which also create micrometer-scale porosity in the structure. The effects of HAP morphology and HAP content on mechanical properties were evaluated.
Orientation of polymer chains has been shown to have a major effect on component properties. The chain orientation at the end of fill of a component is different from most other areas. Overflows have been used in various areas of the plastics industry to improve weld line strength and provide a more consistent gas channel in gas-assist molding. This study will investigate if the use of overflows to change the orientation of the polymer chains provides a more capable molding condition.
Allowing engineering students to work with students of other disciplines offers them an experience they can take with them as they begin their career in industry. The college students take the project from concept to a manufactured product. At the beginning of the project, psychology students interact with sixth-grade students to determine the best features to include in a car. The marketing students will then create a display and video commercial for each car.
The purpose of this project was to determine the effect of overflow tabs on ‘affected area’. It was done because overflow tabs could prove to be very important in the medical industry, where tight tolerance parts are needed. Along with that industry, parts with limited gating locations could also use overflow tabs to provide more consistent flow throughout the part.
This study investigated a rubber-assisted embossing process for structuring thin polymer films. The main advantages of a rubber support instead of a hard counter tool include simplification of the embossing tool, protection of the embossing master, buildup of high pressure, and ease of mold separation. With rubber-assisted embossing, thin polystyrene films in a thickness of 25 ?m were accurately patterned with microgrooves of characteristic dimensions on the order of 100 ?m.
Water-assisted injection molding (WAIM) provides a new means to manufacture hollow parts at lower costs. However, little work has been done to understand how the polymer melt flows under applying high pressure water. Experimental investigations on the melt flow, especially the fountain flow during water-assisted melt filling in an emulated mold were conducted in this work. The experimental results revealed the formation of fountain flow during melt filling under applying high pressure water.
When screw speed is increased, barrel cooling will result to maintain control of the set product temperature. This can lead to barrel temperatures below the crystallizing temperature of the polymer, and a thin layer of frozen polymer can accumulate on the barrel walls. The analysis of this frozen layer or freezeout" condition and an analytical expression for estimating the layer thickness is presented along with supporting data."
For continuously extruded products, such as sheet and profile extrusions, thickness uniformity is a key quality factor, and it is directly linked to flow oscillations or flow disturbances at the die. Many sources of flow oscillations in the extrusion system are identified, and methods are shown on how to configure the melt delivery system to minimize their transmission to the die. These methods are illustrated with a model based on the theory of hydraulic transients.
Finite Element Analysis (FEA) is only as accurate as the material models employed and it must correctly represent application specifics for the FEA to be as precise as possible. Two areas of concern for FEAs of elastomers are cyclic versus non-cyclic testing, and, strain dependent models. Ideally the analyst should be able to choose a strain based non-cycled material model or cycled material model depending on whether the application is a static or semi-dynamic application.
Water-assisted injection molding experiments were carried out on newly developed equipment in our lab. The effects of four processing parameters, short-shot size, melt temperature, water injection delay time, and water pressure, on the water penetration length and residual wall thickness of water-assisted injection molded polypropylene curved pipe were investigated. The crystallization behavior difference between the beginning and the end of the water channel of the curved pipe was analyzed using differential scanning calorimetry.
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Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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