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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Ultrasonic Tests to Monitor Cure of Dicyclopentadiene (DCPD) for Use in Reactive Rotational Moulding
Ultrasound can be used to measure viscosity by analysis of signal velocity and attenuation. This work looks at exploiting change in signal properties to monitor viscosity during cure in reactive rotational moulding (RRM). Results from off-line tests on dicyclopentadiene DCPD show a rise in ultrasonic velocity, and a decrease in relative attenuation during cure, associated with mechanical property changes owing to increased cross-linking. Variations in velocity and attenuation can be used to predict important stages in polymer development. This technique is non-intrusive; a single transducer is mounted on the mould exterior. Pulse-echo measurements are made, allowing additional estimation of part thickness.
Ultrasonic Weld Shear Strength of Mineral Filled and Glass Fiber Reinforced Polypropylene Blends
A study was conducted to determine the effects of inorganic fillers and reinforcements type and concentrations on the joint strength of ultrasonically welded polypropylene. An ultrasonic welding test specimen was designed with the goal of producing shear failure at the welded joint during tensile testing. Twelve formulations of neat, mineral filled, and glass reinforced polypropylene, each at different additive concentration levels, were prepared, injection molded, ultrasonically welded, and tested. The formulations were also evaluated for inherent bulk material shear strength. It was found that the ultrasonically welded joint shear strength reached a maximum at an additive concentration of approximately 30% by weight for all three additive types studied. It was also found that the mineral filled formulations had ultrasonically welded joint shear strengths that were approximately equal to or slightly more than the estimated shear strength of the bulk material, while the glass reinforced formulations had ultrasonically welded joint shear strengths approximately 50% less than that of the bulk material.
Undercutting Mold Performance: Ejection Wear
During mold design, most consideration given to wear in the ejector system is focused on metal-to-metal interfaces. Specifically, attention is paid to the wear between the pins, sleeves, blades, and the bores through which they pass. This research focused on wear that occurred on the metal core during ejection of glass filled plastic parts. This phenomenon has been largely undocumented, and was, in some cases, found to be aggressive. Certain tool steels and copper alloys with hard coatings were shown to be significantly more resistant to this type of wear than others. In addition, product geometry appeared to play a role in the wear process.
Upgrading Recycled Waste Stream Polyethylene by Modification with Nanoscale Clay Hybrids
Recycled polyethylene (RPE) - clay hybrids (RPECHs) were prepared by melt mixing of RPE with modified montmorillonite clay using maleic anhydride grafted polyethylene oligomer (PE-MA) as a compatibilizer. Electron microscopy and X-ray diffractometry revealed that dispersion of hydrophilic clay in the highly hydrophobic polyethylene matrix increased with increasing PE-MA content. The highly dispersed RPECH nanocomposites provide substantially enhanced mechanical properties over neat RPE. The results of experimental parametric studies are reported and applied to new value-added applications for this inexpensive and plentiful polymer resource.
Use of Fitments on Stand-Up Pouches for Liquids
Over the past ten years, there has not only been a growth but also an evolution in the use of cap fitments on flexible packages around the world.In Japan and South America, and to a lesser extent in Europe, the stand-up pouch for liquids, both with, and without, fitment has been used for a number of years as a primary package. In the U S, there has been limited use, and primarily as a “refill” package for a rigid container.A lot of fitment applications started out as pre-made pouches that where then filled on fill/seal equipment. That is currently still true in the limited applications in the US. However, for a number of years, form-fill seal equipment has been used extensively in other countries. This paper will focus on the form-fill-seal application.
The Use of FTIR/ATR to Investigate the Migration of Polyisobutylene in Polyethylene for Cling Film Applications
A range of LLDPE films with polyisobutylene (PIB) content from 2%-8% was manufactured using a Killion cast film extrusion system. The films were aged at 25, 35 and 45°C for up 28 days, to enable tack (cling) development. FTIR/ATR analysis was used to investigate the surface migration of PIB. The results were confirmed by mechanical tack (cling) analysis and these showed increased migration rates with increasing PIB concentration, ageing and storage temperature.A second series of films with 8% PIB content were manufactured from a range of LLDPE's. FTIR/ATR, DSC and mechanical tack analysis were used to investigate the relationship between polymer properties and migration rates. The study established that crystallinity was the most influential factor governing PIB migration and this could be related to polymer density. Co-monomer type was found not to be a factor influencing migration of PIB.
The Use of FTIR-ATR to Investigate the Migration of Automotive Fuel Components in High Barrier Materials used in Fuel Line Applications
A Perkin Elmer Fourier Transform Infra-Red (FTIR) spectrometer with a variable temperature Attenuated Total Reflectance (ATR) attachment was used to investigate the migration of fuel components in a series of fluoropolymer, polyester and polyamide based films at various temperatures. Diffusion of the fuel components in these films was investigated by monitoring the changes in peak height of the infrared spectrum at particular wavenumbers, specific to the individual fuel components. The results show that fuel component migration increases significantly with progressive increase in temperature. The results also show that the diffusion rates increase significantly at temperatures above the glass transition temperature (Tg) of the particular polymer. The diffusion results are similar to those obtained using other techniques such as gravimetric and dynamic permeation techniques, which involve a much more prolonged analysis regime.
The Use of Polymer Processing Additives to Improve Melt Processing of m-LLDPE Extrusion
There is a large body of work showing that the addition of polymer processing additives (PPAs) results in an improvement in the processing performance of polymers. Some of the processing improvements that have been observed include a reduction in melt fracture, pressure, die build-up, and gels along with an increased processing window and improved surface finishes. Previous papers have shown the addition of a PPA has reduced many types of gels that result from cross-linking, oxidization, and unmelted material. This paper will investigate the reduction of unmelt gels seen with the addition of PPA to a polyolefin plastomer (POP) and will infer the mechanism of how the coating of the PPA on the extrusion barrel reduces the unmelt gels. In addition to the mechanism this paper will evaluate the different methods of adding the PPA to the extrusion system.
The Use of Three-Dimensional Computation Fluid Dynamics in the Design of Profile Dies
Efficient fully three-dimensional, non-Newtonian flow algorithms have been available for several years to aid in the design of flat extrusion dies . However, there are few tools available, which can be used in a practical way by an engineer tasked with designing a complex profile die in a reasonable period of time. This paper demonstrates through an actual example how the efficient use of 3-D CFD algorithms and automatic finite element mesh generators can be used to eliminate much of the cut and try" from profile die design. The effect of die swell on the profile shape downstream of the die exit is also examined."
The Use of Zinc-Neutralized Ethylene-Methacrylic Acid Copolymer Ionomers as Blend Compatibilizers for Nylon 6 and Low-Density Polyethylene
The effect of composition on the morphologies and properties of uncompatibilized and compatibilized blends of nylon 6 and LDPE were studied over a wide range of weight fractions. The mechanical properties of the uncompatibilized blends had reduced tensile and impact strength after mixing, which was almost certainly due to poor interfacial adhesion between the two polymers. It was found that the addition of a zinc-neutralized poly(ethylene-co- methacrylic acid) ionomer as a compatibilizer can improve mechanical properties. Micrographs showed that the ionomer caused a reduction of the dispersed phase size, especially when nylon 6 is the dispersed phase of the blend.
Using a 2(cubed) Full Factorial Plan to Analyze the Effect that the Reaction Temperature, Al/Zr Ratio, and Pre-Contact Time Has on Propylene Polymerization Employing a Metallocene Catalyst
The influence of the reaction temperature (T), the Al/Zr ratio (Al/Zr) and the pre-contact time (t) on propylene polymerization using Et(Ind)2ZrCl2 (rac-( ethylenebis(indenil))zirconium dichloride) as the catalyst, and hexane as the solvent, was evaluated using a 23 full factorial plan. All the evaluated properties were mainly affected by the reaction temperature. The catalytic activity and the xylene solubles increased when T increased. Both the melting and the crystallization temperatures, the crystallinity, and the molecular weight decreased when T was raised.
Using Blow Molding Simulation Software as a Troubleshooting Tool
Currently, after a new blow molded part is designed, the molds are built then modified until a desirable part is produced. This results in higher mold costs and longer time to market. From the industry standpoint, blow molding simulation software could lower mold costs by predicting potential problems before a mold was built. Potentially, companies could test molding scenarios to determine the feasibility of the design without ever cutting steel. A considerable savings in labor and scrap costs could result. The focus of this research was to determine how effective blow molding simulation software would be when used as a troubleshooting tool.
Using Neural Networks to Predict Injection Molded iPP Shrinkage
Shrinkage occurs in all polymers and it is extremely dependent on processing conditions, like holding pressure, holding time, injection speed, mold temperature and melt temperature.The utilization of shrinkage data allows designers to predict the final part dimensions accurately. Numerical prediction of the part shrinkage can be made using simulation packages availables commercially. However, a part shrinkage involves non-linear material behavior and its estimation involves significant simplifications. The neural networks can model highly non-linear systems and predict a part shrinkage effectively.In this study, a neural network architecture was developed to predict the shrinkage of an iPP injection molded part at several process conditions defined through the design of experiments.
Using Recycled Concrete as a Filler in Polyethylene Resins
Adding concrete fillers to base plastic materials can increase mechanical properties such as tensile strength, flexural strength, and hardness. This can be done through the addition of fillers to a virgin and recycled plastic material. By increasing these properties, plastics can be used in applications where they were not previously used.The effects of compounding concrete filler with polyethylene were studied. Two different percentages of the concrete fillers were added to test different properties against a NEAT (nothing extra added to it) sample of both recycled and virgin polyethylene.
Variation of Electrical Properties with Exfoliation Condition in Nanocomposites
Dielectric measurements were made on clay filled nylon and polyethylene-ethyl vinyl acetate (PE-EVA) copolymer nanocomposites during processing by extrusion. Nylon without clay had a small dielectric dispersion while PE-EVA did not. The addition of Na treated clay to the PE-EVA copolymer increased the dielectric constant (relative permittivity) above that of the PE-EVA copolymer but did not increase the conductivity or cause any dispersion. In both PE-EVA and nylon, addition of akyl ammonium chemically treated clays gave substantial increases in dielectric dispersion that are associated with the intercalated or exfoliated state. X-ray diffraction measurements were made on the composites.
Various Plug Assist Materials and Their Effect on the Thermoforming Characteristics of Polymeric Sheet
Plug assist thermoforming is an art which thermoformers have developed through many years of experience. As the industry becomes more competitive and expands into increasingly difficult products, modeling of the process holds the potential to dramatically shorten development time, increase process and materials efficiencies and lead to new market opportunities.This report presents the results of investigating the force-deformation characteristics of a HDPE polymer sheet when formed with different plug assist materials with the aim towards developing modeling parameters. The variables investigated were plug material, plug temperature, plug speed, plug shape, plug surface roughness and polymer sheet thickness and temperature.
Versatile Manufacture of Barrier Materials by Chaotic Mixing
Recent studies have demonstrated that highly multi-layered films can be formed by chaotic mixing and extruded in various shapes. The number of layers prior to breakup and the extent of breakup are controllable so that versatile manufacturing and property optimization are possible. Layer breakup can yield distinct blend morphologies. Where layer breakup is likely, a large number of platelets form that may be associated with attractive barrier properties. Although methods can be applicable to other blends, the relation of oxygen permeability to various morphologies was specifically investigated for extruded films consisting of ethylene vinyl alcohol copolymer, low density polyethylene and maleic anhydride as a compatibilizing agent.
Vibration Control Effect of Epoxy Beam Sandwich Structure Composites Utilizing Shape Memory Poly (Ethylene Terephthalate)-Poly (Ethylene Glycol) Copolymer
Shape memory PET-PEG copolymer was synthesized by coupling polyethyleneglycol (PEG), a soft segment, to polyethyleneterephthalate (PET) that was made from dimethylterephthalate (DMT) and ethyleneglycol (EG). In addition, maleicanhydride, glycerine, or d-sorbitol was used as a cross-linking agent to enhance its shape memory and vibration control. Sandwich structure consisting of PET-PEG copolymer/epoxy composite laminate was prepared from the above copolymer and glass fiber containing epoxy beam. The mechanical properties as well as vibration control effect were compared while varying the kind of cross-linking agents, and their composition.Finally, enhanced vibration control effect was observed with the proper selection of cross-linking agent and the percentage of incorporation, together with the control of temperature range that showed damping effect.
Vibration Welding of Thermoplastic Polyolefins
Thermoplastic Polyolefins have been extensively used in the automotive industry as well as in other applications. The information about using vibration welding to join these materials is limited. Therefore, the main objective of this paper is to perform a design of experiments and to determine the optimal welding conditions for specific thermoplastic polyolefins materials. A three factor (meltdown, pressure and amplitude) two level full factorial design of experiments was performed. The results indicated that the welding time is a strong function of the vibration amplitude and is less sensitive to meltdown and pressure. In addition, the welding strength is not sensitive to the welding parameters. This result was confirmed by hot plate welding of butt joint samples.
Vinyl Foam Technology: Trends / New Developments
Vinyl foam extruded sheet, profile, and pipe products are in growing demand as a replacement for softwood and for non-foamed PVC in many building and construction applications. As a wood replacement, rigid vinyl foam offers good weatherability, chemical resistance, and flame retardancy and it can be saw n, nailed, and screwed. As a maintenance-free product, it is in growing demand in the building industry. Vinyl foam products are considered as a replacement for non-foamed PVC mainly on the basis of economics. This is especially true in the foam -core pipe market, when with weight reductions approaching 40% , a significant cost saving can be realized. The properties and economics of the extruded product depend critically on both the formulation and the processing conditions. This paper focuses on the new trends and technology developments that have taken place and the effect these have had on these three major vinyl foam markets.
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