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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Melt Temperature Field Measurement in Single Screw Extrusion: Influence of Melt Pressure and Die Geometry
Melt temperature fields have been measured in single screw extrusion using novel thermocouple grid, ultrasound and infra-red sensor techniques. The effect of die geometry on melt temperature profile has been investigated using simple slit and rod dies on a single screw extruder. Die geometry of the simple dies studied here was found to have a minor effect on melt temperature field in regions near to the die wall. Die head pressure had a more significant effect on melt temperature distribution.
UV Curable Coatings for Automotive Lighting
In the last few years, UV curable coatings have gained great interest among numerous automotive OEMs and finishers because it allows for more efficient manufacturing, improved performance properties and an overall more environmentally friendly process. In consideration of this interest, the automotive lighting sector should be evaluated as a benchmark for early UV technology success as well as continued innovation in terms of appearance, performance and processing advantages.
Troubleshooting the Ultrasonic Welding Process: The Interpretation of Welding Graphs in a Thermoplastic Plunge Welding Process
This paper will explain the intricacies of interpreting the graphs of the ultrasonic welding graphs. Further, it seeks to explain how these graphs can be used to optimize welding results, troubleshoot welding difficulties and document the process for future use.
Compounding of Conductive Polypropylene/Graphite Composites
Polypropylene (PP) and Natural Graphite Flake (NGF) composites were prepared by three methods using a high-speed thermo-kinetic mixer. The electrical conductivity of the materials was measured as a function of NGF content. Mechanical and rheological properties were characterized to assess the composite's potential to be processed for applications such as fuel cells.
Environmental Stress Cracking – Examples from the Automotive Indsutry
Four case studies are presented to illustrate environmental stress cracking (ESC) within automotive components. ESC is a very important mode of plastic component failure. The presented cases illustrate how the failure analysis process was used to identify the failure mechanism as well as the primary factors responsible for the failures. The four cases depict representative automotive failures involving varied designs and service conditions.
Injection Velocity Control in Plastic Injection Molding
Injection velocity is a difficult process to control due to its complexity and nonlinearity. Different dynamic characteristics with variations in melt temperatures and materials occur. A control strategy using simplified predictive control (SPC) was developed and implemented for injection velocity having wide ranging multiple velocity profiles. The experiment results have shown that the SPC control of injection velocity has good setpoint tracking performance.
The Effect of Calcium Carbonate Particle Size on PVC Foam
CaCO3 is the predominant filler used in polyvinyl chloride compounding. Selection of fillers, as in the case with other compounding ingredients, involves consideration of available types and their effects on processing, product properties, and economics.In this paper the effect of the particle size of CaCO3 on the properties of PVC foam is investigated. The paper analyzes the correlation between fusion time, extrusion torque, and foam density as well as foam cell structure with the filler particle size.
In-Process Monitoring and 3D Dimensional Assessment of Micromouldings
Advances in micromoulding technology are realizing detailed products having sub-milligramme masses. In order to create a viable manufacturing process for these components, accurate process monitoring and product evaluation are essential. This paper describes work implementing a suite of sensors on a commercial micromoulding machine for detailed process interrogation. Evaluation of demoulded products is performed with a single camera based system combined with custom software to allow for 3-dimensional characterisation of products during the process.
Initial Expansion Behavior of Butane-Blown LDPE Foam at Extrusion Die Exit
A CCD camera was used to observe n-butane-blown LDPE foams at the extrusion die exit. The effects of butane content, nucleating-agent (talc) content, aging modifier (GMS), die temperature, and geometry on the initial expansion behavior of the foam extrudate were studied. A transparent section of the foam extrudate was found at certain die temperatures. The reasons for the existence of this transparent section and its effect on the processing conditions and material formulations are discussed.
The Manufacture of Aligned Poly(Acrylonitrile) Fibres by Electrospinning
Electrospinning is a process used to obtain nano-diameter randomly deposited fibres by electrostatically drawing a jet of polymer solution onto an electrically grounded metal sheet. This work reports on a novel method of obtaining aligned fibres of poly(acrylonitrile) (PAN) by means of an electrospinning process and investigates the effect of polymer solution concentration and take off speed on fibre diameter and molecular orientation.
Mechanical Properties of Short- and Long-Glass Fibrereinforced Polypropylene Compounds
The tensile and impact properties of two short- and two long-glass-fibre-reinforced polypropylene compounds were measured on injection-molded and machined specimens. It was found that mechanical properties were strongly dependent on the glass fibre length and orientation with respect to the flow direction.
Overview of Property Development in Layered Silicate Polymer Nanocomposites
This work reviews approaches to fabrication and property development in various layered silicate polymer nanocomposites, including the roles of thermodynamics and hydrodynamics in determining the nanoscale structure. Material is taken from the specific research of the author over the past decade, with emphasis on nanocomposites comprising polymer blends, as well as from some of his prior review papers (1, 2, 3).
Modeling and Process Optimization of Nano-Modified Simulant Energetic Materials
Nanofibers were added to simulant energetic materials via twin screw extrusion (TSE) to characterize the degree of dispersion of the fibers into a highly filled polymer composition. This work was an attempt to optimize process conditions resulting in maximum dispersion and minimal fiber breakage without excessive heat buildup. Theoretical melt temperatures were predicted via an energy balance equation. Trials showed the polymer viscosity could be reduced enough to allow the addition of the model filler and nanofibers in a single downstream feedport by gravity.
Exfoliation in Pa-6/Clay Nanocomposites by Melt Processing
Nanocomposites prepared by various methods were characterized using transmission electron microscopy, wide angle X-ray diffraction, mechanical testing and oxygen permeability measurements. Correlations were made between structural parameters (e.g. aspect ratio, dspacing) and the mechanical and barrier properties of the nanocomposites. Higher aspect ratios of filler lead to significant improvements in mechanical and barrier properties.
ESCR Thresholds Evaluated by Observation of Interfacial Surface Energies
This work probes a hypothesis for initiation of environmental stress cracking (ESCR) based on a thermodynamic criterion for localized stress induced swelling. The threshold metric involves observation of solid-vapor surface energy and contact angle of a liquid on a loaded polymer substrate and thus inference of solidliquid interfacial surface energy with respect to substrate stress. The intent is to develop a screening technique for ESCR that is not limited by the kinetics of the crazing event.
Solid-State Processing of Polymer in the Presence of Supercritical Carbon Dioxide
Open cell microporous bisphenol-A polycarbonate (PC) films are made by a novel, solvent-free processing: drawing PC in supercritical carbon dioxide (scCO2). The pore size is less than 1.0 micron and the porosity is in the range of 20%-70%, and is highly tunable. The porous film has mechanical properties nearly as high as the original film. The influence of temperature and pressure on drawability, porosity, and mechanical integrity are systematically studied.
Crystallinity and Orientation Development in Poly(L-Lactic Acid) Fibers during Annealing and Drawing
The crystallinity and orientation development in melt-spun poly(L-lactic acid) (PLLA) fibers are studied by in-situ synchrotron 2-D wide-angle x-ray scattering under various thermal and mechanical treatments. Crystalline orientation is evaluated from the azimuthal profiles of (200) and (203) diffractions. Crystallinity and orientation are found to be strongly dependent upon the take-up speeds of spinning. When fibers are heated above the glass transition, re-crystallization is observed. The effect of drawing above Tg on crystallinity and orientation are also characterized.
Degradaton Mechanisms and Environmental Effects on Poly Pphenylenebenzobisoxazole (PBO) Fibers
Recent reports have shown the fibers made from polyp- phylenebenzobisoxazole show a significant reduction in properties after relatively mild exposure to environmental conditions. This paper discusses potential mechanisms responsible for the degradation and reports results on degradation of fiber properties due to various environmental exposure conditions.
Extrusion Pulverisation of Elastane Fibres
A novel ram extrusion process for the size reduction of various grades of poly(urethane urea) (PUU) fibres (elastane) is described in this work. The process was performed over a range of shear rates and temperatures. SEM and GPC analysis results showed significant reduction in both particle size and molecular weight of the poly(urethane urea) as a result of the extrusion pulverisation process.
Properties of the Oxidized HDPE Obtained from Continuous Extrusion Blow Molding Process Machinery
Deterioration of a barrel sleeve in a forwarding and solids compaction zone of a blow-moulding unit increases the heat exchange time and negatively affects the stability process.It has been shown that gel, formed by oxidation and structurization of high-density polyethylene (HDPE), sharply differs from HDPE in density, fluidity, dissolution of additives, and interaction with a metal surface.The research established the reason of worsening quality container and restoring stability of blow moulding.
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