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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Viscoelastic Properties of Nylon 12 and PVDF
We report the time and temperature dependant properties of Nylon 12 and PVDF characterized using linear viscoelastic theory based on the Boltzmann superposition principle. Dynamic mechanical properties of both polymers were scanned isothermally at intervals of 10°C between 30 to 140°C for five different frequencies, 0.3, 1, 3, 10 and 30 Hertz. Stress relaxation measurements were made using a Zwick tensile test machine between 25°C and 140°C at 10°C intervals using a crosshead speed of 50 mm/min to a maximum strain of 2%. The DMTA and stress relaxation data were compared by converting temperature dependence at constant frequency, into a time dependence at constant temperature. The increase in temperature was converted to a corresponding increase in time using log aT (shift factor) data superposed at 30°C. Good agreement was obtained between the stress relaxation modulus E (t) calculated from the dynamic modulus E`(?) and from that measured experimentally. These results will be used for the prediction of the thermoforming characterisation of multi-layer tubing.
Viscosity Characterization of Bulk Molding Compounds
Viscosity variations in bulk molding compounds have long been a concern. The reactive nature of the polymer, response to thickening agents, high filler and glass loading, all contribute to this variance. Additionally, environmental factors such as storage temperatures and humidity affect the viscosity of these compounds.Confounding the issue is the often forgotten about gage variation. There have been many test methods developed in an attempt to characterize the viscosity of bulk molding compounds. Most of these contribute, as much, if not more to the total variance.This study examines viscosity characterization methods for bulk molding compounds
Viscosity Measurements on Polypropylene Mixed with Supercritical Fluid at High Shear Rates
Viscosity of polymer melts can be effectively reduced by adding constituent of supercritical fluid (SCF) during plastic processing. The viscosity reduction depends on the amount of SCF added and also the magnitude of shear rate. This research modified a conventional injection-molding machine to investigate the rheological behavior of PP/SCF mixture. By measuring the pressure and flow rate of the melt at a slit die which was attached in front of the nozzle, the true viscosity can be obtained after making Bagley and Rabinowitsch corrections. By using this machinery, the shear rate can be achieved as high as order of 1E4 1/s .
A Visual Approach to Better Failure Analysis
Much has been written outside of the technical fields on how to communicate more effectively in groups. The concepts on visually mapping information are directly applicable to conducting a more thorough failure analysis. This is especially true for issues involving cross-functional teams with multiple parties. Studies have concluded that people can process significantly more information visually than they can verbally. A picture is truly worth a thousand words. Cause Mapping is a systems-thinking" approach to visually analyzing documenting communicating and solving complex problems. This presentation will demonstrate an effective approach to failure analysis using a common tool like Microsoft Excel."
Visualisation and Analysis of LDPE Melt Flows in a Coextrusion Geometry
Experiments were performed to enhance our understanding of the interfacial instability phenomena of polyolefin melt flows within a slit coextrusion die. The die configuration allowed a single polymer melt to be used, by using a modular flow cell consisting of a flow splitter, convergent section and die land. The whole of the confluent region and die land are visible through side windows. A further window perpendicular to the flow enables the use of laser sheet lighting for particle imaging techniques. Stress fields in the confluent region and the die land are determined by analysis of birefringence. The die design and experimental techniques allow exploration of the effects of geometry and processing parameters on the source and nature of flow instabilities. Two low density polyethylene melts were studied. Interface instability is observed in the die land for one of the polyethylenes and this results in a 'wave' type distortion of the extrudate. The instability occurs at specific layer thickness ratios.
Visualization of Drop Breakup in Polymer-Polymer Systems
This work studies the deformation and breakup of a single viscoelastic polymer drop inside a viscoelastic polymer matrix using a specially designed transparent Couette apparatus with well-controlled shearing and temperature conditions. Drop deformation and breakup mechanisms were observed through two video camera systems. Polyethylene/polycarbonate (PE/PC) systems over a wide range of viscosity ratios were studied. Two main breakup modes were observed: 1) erosion from the surface of the drop in the form of thin ribbons and streams of droplets and 2) drop elongation and drop breakup along the axis perpendicular to the velocity direction. This is the first time drop breakup mechanism 1) has been visualized in polymer systems.
The Water Injection Technique (WIT) as an Attractive Alternative and Supplement to Gas-Assisted Injection Molding (GAIM)
The water injection technique (WIT), developed at the Institute of Plastics Processing (IKV), Aachen, Germany, is an innovative specialty injection molding process that is closely related to the well-known gas-assisted injection molding (GAIM). The primary aim of the development was to reduce cooling times in the material-saving production of hollow plastics articles by means of using water as a process medium for melt displacement. Besides other advantages, especially the considerably more efficient cooling effect of water meant that cooling times could be reduced by up to 70 % compared with GAIM. Investigations on a wide range of unfilled and filled materials show that WIT constitutes an attractive alternative and supplement to GAIM.
Water Processing Using Polyamide Membrane
Desalination by reverse osmosis and by ion exchange technologies are compared with each other. Now polyamide membrane made from all trans stereoisoner of cyclopentanetetracarboxylic acid chloride by interfacial reaction of m-phenylenediamine, trimeosyl acid chloride A copolymer blend design may be used to prepare a thin film membrane. Turbulent flow keeps the concentration polarization layer thickness low. Composite ion exchange resin is prepared with poly styrene copolymer matrix crosslinked with divinylbenzene with macro reticular structure and weakly basic resins. The macropores in the matrix is filled with acrylic acid copolymer crosslinked with divinyl benzene and weakly acidic groups.
β-Crystalline Polypropylene (Bepol™) and Oriented Film Applications
Polypropylene with high ?-crystalline content is obtained by employing a ?-nucleator, such as ?-quinacridone, N,N’-dicyclohexyl-2,6-naphthalene dicaboxamide or a combination of a Group II metal salt or hydroxide and an organic di-acid compound. In this case, Bepol™, a ?-crystalline polypropylene, contains a small amount of a Group II metal salt or hydroxide and an organic di-acid compound. In this study, various products of Beopl™ have been characterized and applied to oriented film.
"Born" Exporting in the Mould Cluster of Marinha Grande
Empirical evidence on the start-up of two plastic moulds exporters located in Marinha Grande, Portugal, illustrates the process through which location within a cluster contribute to explain how start-ups manage to be born" exporters.Relations within a cluster tend to be frequent and long lasting encouraging information flows and trust. These play an important role in detecting opportunities and in accessing resources. Furthermore outward oriented clusters attract foreign buyers and facilitate unplanned contacts."
Extrusion Defects in Filled & Rubber-Modified Polypropylenes
Visual observations of the surface texture of the extrudate strips obtained with a strip die are reported here for a PP homopolymer a blend of this PP with oil and a TPV produced by blending the PP/oil mixture with EPDM rubber. This was done to understand the causes of pit formation on TPV extrudates. The local packing of crystallites influenced by the degree of stretch seems to correlate with the pit formation in extruded PP/oil mixtures and TPVs.
Polyester Resin System Utilizing Renewable Sources - Soybean and Corn
A resin that utilizes 25% grain-derived organics has been developed. Ethanol and soybean oil are reacted with other materials to produce a durable polyester resin capable of equal or better performance than current polyester resin systems. Utilizing the sheet molding compound (SMC) molding process this unique renewable-source polyester resin has successfully produced large combine parts for use in the agriculture industry. The transportation industry is investigating this resin for use on upcoming vehicles.
Development of a Structural SMC Pickup Box
The Ford Explorer Sport Trac pairs the comfort and convenience of a sport utility vehicle with the added utility of a cargo bed for one-vehicle-does-it-all" versatility. The cargo bed is a combination of structural SMC for the box inner tub and Class A SMC outer body panels. As this application represents a very aggressive use of structural SMC and the first production composite pickup box in the automotive industry this paper will discuss the evaluation of structural SMC material properties pickup box laboratory component testing and on-vehicle Arizona Proving Ground (APG) durability testing."
Topics of this paper are recent progress in 3-D orthogonal weaving composites made with 3-D woven preforms their mechanical properties and applications. The patented fabric combines no-crimp in-plane fiber reinforcement with integral through-thickness fiber reinforcement. The latter one enables to suppress delamination and substantially improve interlaminar strength and damage tolerance. 3-D orthogonal woven preforms are especially suited to composites processing using RTM technique. Also such composites are characteristic with fairly predictable basic mechanical properties allowing to apply conventional modeling and predictive analysis tools.
A Molded-in-Color UV-Stable Sheet Molding Compound: One Step Beyond
An ultraviolet (UV)-stable pigmentable system which is designed to be formulated into sheet molding compound (SMC) for external structural applications and which eliminates the need for paint is now available. Hailed as “the next generation of SMC” the formula meets original equipment manufacturers’ (OEMs) requirements for pickup truck box applications. The material has excellent mechanical properties and after 10000 hours of weathering the material retains its color and appearance without a need for painting.
New Preforming Method & Binder for Liquid Molding Processes
PowerPoint Presentation at ACCE 2001.
Status of Microwave Adhesive Bonding Research
Microwave adhesive bonding has resulted in significantly shorter bonding times and stronger bonds for some systems. Compared to single mode microwave adhesive bonding variable frequency mode-switching microwave adhesive bonding was applied to obtain uniform heating in microwave adhesive bonding of large-size materials. A new method was developed to monitor in situ microwave adhesive bonding of large samples. Process control programs were developed to intelligently control the microwave adhesive bonding process.
Injection Molding of Wholly Thermoplastic Composites
Thermotropic liquid crystalline polymer reinforced thermoplastic polymer strands were spun and used in injection molding to form wholly thermoplastic composite materials. While keeping the strand size suitable for injection molding an effort was made to increase the orientation and aspect ratio of the reinforcing TLCP fibril. The pelletized strand was injection molded without disturbing the TLCP reinforcing fibrils. The samples have similar mechanical properties lower density and smoother surfaces compared with glass fiber reinforced samples.
Thermoplastic Sandwich Structures for Semi-Structural Automotive Parts
PowerPoint Presentation at ACCE 2001.
New Instrument for Dynamic Mechanical Analysis with Controlled-Temperature Exposure to Fluids or Humidity
A new dynamic mechanical analyzer with special fluid bath furnace has been developed to measure the mechanical and thermal properties of materials while immersed in fluids or exposed to humidity. This technique is superior to traditional methods of first exposing the material and then performing the measurements. Such experiments are performed on several materials including oil filter paper and an epoxy coating. The former material is immersed in engine oil and shows post-curing behavior. The epoxy is measured in both air and salt water (saline). The saline experiments show that the traditional method (in air) can lead to anomalous results.
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