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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Compressibilty of Resin, A New Look at Bulk Density
The bulk density of a material greatly influences the total storage capacity in a silo. Although it has significant meaning, little research has been done in determining how compressive polymer materials are in their bulk states. The focus of this research is to investigate the changes in bulk density that occur with changes in pressure for several different polymer materials and determine the compressibility of these materials in the bulk state.
Analysis of the Stability of a Single-Screw Extrusion Process Using Graphical Analysis
This paper analyzes the barrel pressures and motor current data acquired using a high-speed data acquisition system. Graphical analysis shows the relationship between screw design and screw speed.
What Every Plastics Professional Should Know about Products Liability- Part 1: An Overview of Sources of Products Liability Claims
This article, particularly tailored to cover plastics materials products, provides an overview of the three major theories under which a products liability action may be initiated, namely; negligence, breach of warranty and strict products liability. Negligence liability claim elements of duty owed by the manufacturer, breach of duty, causation and damages are discussed. Also, discussed are claims brought under the theories of breach of warranty and strict products liability.
Polybutene-1: A Review of an Old Polymer Produced with a New Technology and its Application to Flexible Packaging
Polybutene-1 is a polyolefin with unique characteristics which distinguish it from PE and PP. They include: low heat of fusion, shear thinning, creep resistance and an intriguing polymorphic structure. Compatibility of PB-1 with PP and immiscibility with PE are often exploited to create convenient packaging which is easily opened by the consumer. This paper will review examples of the use of PB-1 in such applications and in the modification of the sealing initiation temperature of films.
Modeling of a Thin-Walled Filament Wound Tubing
There is a need in biomedical engineering for thin-walled, high-performance structures, which could be used as catheters, or as replacement implants in the body. Reinforced thermoplastic materials are becoming exceptionally important due to their ease of fabrication and reduced costs of manufacture. This paper outlines the theoretical modeling of a filament wound catheter and the associated outputs from which a catheter with specific required properties may be designed.
Rheological and Degradation Properties of Renewable Resource Polymer Blends
Over the past decade, considerable interest has emerged in replacing conventional fossil fuel-based polymers with bio-derived polymers. Two bio-derived polymers that have garnered significant interest are PHA and PLA. In this study, shear and extensional rheology, coupled with degradation studies using GPC, are used to investigate the flow properties of blends of these two polymers. The development of blends with tailored flow and thermal/mechanical properties is pursued.
The Effect of Long-Chain Branching on Extensional Rheoelogy and its Correlation as a Predictor for Molecular Architecture
The effect of sparse long-chain branching on extensional rheology is analyzed for metallocene-catalyzed polyethylene resins with varying degrees of branching. The onset of extensional strain hardening distinguishes the degrees of branching while such distinctions are not apparent in shear flow behavior.
Mar Behavior of Thermoplastic Olefins
Work has recently been conducted at Texas A&M University to evaluate the mar resistance of thermoplastic olefins using a modification of a currently established ASTM standard (ASTM D7027-05). This work strives not only to examine how the mar" is formed but also to illustrate the potential for this methodology to be established as a quantitative method for evaluating mar resistance of polymers. Approaches to improve mar resistance of polymers are also discussed."
Effect of Material Properties and Processing Conditions on PP Film Casting
Film casting is a common industrial process used to produce polymeric films. The material properties and processing conditions have a significant impact on the process and the final thermal/mechanical properties. We experimentally investigate the impact of polymer molecular weight on the films. The effect of process conditions and post-processing steps like uniaxial stretching, on film strength, orientation and crystallinity is also studied. The measured velocity and temperature profiles are compared to model predictions.
Optimizing the Reaction Injection Molding Process using Polydicyclopentadiene
The variables that contribute to the processing difficulties of Polydicyclopentadiene (PDCPD) are many and not well understood. A screening designed experiment was run to determine the most vital of these variables. It was found that all of the variables had a significant effect on the mechanical properties of the PDCPD parts. A Central Composite designed experiment was then run to determine the optimum processing parameters including all of these significant variables.
Use of Injection Speed Profile to Achieve a Uniform Void Fraction Distribution in Injection Molded Structural Foams
The change in pressure drop and pressure drop rate at the gate of the mold during the structural foam molding process results in an inevitable nonuniform void fraction along the melt flow direction in injection molded structural foams. The nonuniform void fraction not only reduces the achievable void fraction but also can deteriorate the mechanical properties of structural foams. In this paper, an effort has been made to overcome this problem with various injection speed profiles.
Investigation and Modification of the Melt Rheology of Olefin Block Copolymers
The melt rheology of novel Olefin Block Copolymers (OBCs), recently developed by The Dow Chemical Company, was investigated. The melt shear rheology of OBCs was found to be characteristic of linear random copolymers of ethylene and __olefins. Furthermore, the melt rheology can be modified to target certain specific application areas by chemical means or by blending with traditional polyolefins with broader molecular weight distributions or those containing long chain branching.
The Effect of Carbon Nanotubes on the Crystallization Behavior of Polyethylene Oxide
The effect of well-dispersed carbon nanotubes on the crystallization characteristics of polyethylene-oxide was studied. The specimens were prepared via the solution-sonication procedure. The results confirm the effectiveness of CNTs as nucleation agents for semi-crystalline polymers.
Fracture Behavior of Medium Density Polyethylenes by Essential Work of Fracture (EWF)
The Fracture behavior of Medium Density Polyethylenes (MDPE) with different melt flow indexes (1.9 to 5.0 dg/min) employed in rotational molding were studied by Essential Work of Fracture (EWF). The EWF parameters obtained were equivalent for all samples examined regardless of their differences in comonomer content and molecular weights. Annealing of samples resulted in lower ductility values according to EWF parameters, in spite of minimum crystallinity changes.
A Parametric Study on the Processing and Physical Characterization of PLGA 50/50 Bioscaffolds
In this study, the effects of processing parameters on cell morphology and mechanical properties of PLGA 50/50 bioscaffolds for tissue engineering applications were investigated. The PLGA samples were processed using a salt leaching technique in a batch foaming setup. The foaming parameters were varied, and the physical and mechanical properties of the scaffolds were investigated.
Improving Surface Finish Quality on 3D Printed Metal Tooling by Altering Infiltration Practices
This work investigates improvement techniques used with 3D printed metal parts during the infiltration treatment. By extending the infiltration cycle and applying a planar contact surface to the face of a sample, reductions in roughness of 76% are possible. The goal is to produce injection mold tooling with an acceptable surface quality without performing a secondary machining process.
Process Considerations for UV Curing of 3D Decorated Plastic Parts
The use of UV coatings, inks, and adhesives on thermoset and thermoplastic substrates continues to grow at a rapid rate. UV and electron beam curing has moved from primarily curing of inks to functional and decorative coatings. One of the areas with the highest growth rate is the use of industrial coatings on 3D parts. Processing of 3D part presents a number of challenges – the critical process challenge is that UV curing requires line-of-sight to achieve activation and cure.
Mold Thermal Design: A Simplified Approach to Predict Part Temperature and Minimum Safe" Cycle Time"
In an injection molding operation, the mold temperature increases from its initial value until a steady state is reached, therefore the minimum required cooling time also increases. Improving the mold thermal design will decrease the cooling time thus reducing total cycle time. The goal of this work is to develop software capable of simulating multiple cycles while balancing simulation time with accurate results. Three case studies are presented, one done in our labs and two on-site at an automotive manufacturing facility.
Nucleation and Crystallisation of PLA
Unless it can be properly crystallized, the field of applications for poly(lactic acid) will be limited by its low glass transition temperature. This paper discusses different strategies that can lead to partial crystallization within typical polymer processing conditions. X-ray techniques and DSC analysis are used to access the crystalline content developed in various molding and extrusion conditions and as a function of plasticizer and nucleating agent content.
Grooves in Scratch Testing
For a number of polymers with different chemical structures and different properties, we have determined scratch resistance and sliding wear. We have determined cross section areas of the grooves including the groove and side top-ridge areas. The nanohardness of the polymers was also determined using nanoindentation testing both inside and outside the grooves. A relationship between the hardness and the groove areas has emerged.
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