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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Injection-Molding Degradation of Biodegradable Polylactide
The effects of degradation on the mechanical and aesthetic properties of injection-molded biodegradable polylactide (PLA) parts were studied. Standard tensile test specimens were molded from NatureWorks 3051D injection-molding grade PLA. Barrel residence time, machine nozzle temperature, and shear rate were varied during the injection-molding process. The resulting specimens were analyzed in a tensile testing machine. Tensile strength, tensile modulus and visual inspection were used to characterize the extent of degradation that occurred during each process.
Investigation of Failures in a Polypropylene Water Piping System
Polypropylene pipe and fittings were selected for a high-purity, highly chlorinated water system in a medical research facility. In the first four years of operation, the system sustained an excessive number of leaks. This paper is an account of the investigation of the causes of those leaks.
High-Energy Electron Beam Processing of Wood Composites
For high doses, a DMA analysis of wood and composites revealed a change in lignin resulting in reduced Tg, and that electron scavenging from lignin's aromatic structure could hinder the cure. An investigation of purified cellulose revealed changes at higher doses in the physical response to moisture and thermal stability without a change in the degree of crystallinity as measured by wide-angle X-ray scattering (WAXS).
Developments in Water Assisted Injection Molding Process Technology and Simulation
A preliminary account is given of issues involved in numerical simulation of water assisted injection molding (WAIM), extending techniques used previously for gas assisted molding. An industrial scale, instrumented process is used to guide and validate the simulations. Novel sensor technologies, including ultrasound, are used at process to monitor the position of the water bubble during filling, together with melt pressures and temperatures as well as the residual wall thickness.
In-Mold-Fabric Decorated Parts with a Plastic Trimmed Edge
Several processes currently exist that produce a thin-walled part with a fabric-covered surface. These processes, however, are limited by cost, low production volumes, and durability of the part. A new process is described here that produces a high-quality and durable, thin-walled part using low-cost mass production techniques.
Effect of Additives on the Color & Appearance of Plastics
The color and appearance of a formulation must be engineered just like any other desired thermal or mechanical property of the resin itself. The ability to achieve the desired color can be adversely affected by processing or the combination with modifiers and additives in the resin system. Even if colors can be achieved, other performance attributes such as UV stability, flammability or mechanical properties may be adversely affected as well. This paper looks at some of these color concerns.
Effects of Molecular Weight Distribution on the Formation of Fibers of Electrospun Polystyrene
It is widely recognized that molecular weight distribution (MWD) is an important factor affecting the rheological behavior of polymer solutions. In this contribution, the effects of MWD on the formation of electrospun polystyrene fibers in THF have been studied. The results are compared with the monodisperse system. The importance of chain entanglements attributed to high molecular weight component within the polydisperse system has been acknowledged. Concentrations for the incipient as well as stable fiber formation in a polydisperse system may be predicted.
Reinforcing Virgin, Reprocessed or Recycled Polypropylene with Agave Fiber and a Polymeric Coupling Agent
The capability of using residual agave fibers from the tequila production process, to reinforce virgin, reprocessed or recycled polypropylene, is studied. Polypropylene composites were prepared with milled (65 mesh) agave fibers and Epolene E-43 in a twin screw extruder, varying the amount of fiber. Tensile, impact and dynamic tests, along with scanning electron microscopy observations were carried out. The importance of polymer-fiber interaction through the presence of the coupling agent is clearly shown.
Evaluation of the Melting Capacity of Three Single Screws
The instantaneous melting rate of single screw extruders are primarily affected by the screw speed, barrel temperature and screw diameter. However, with all things being equal the overall melting capacity of the screw is controlled by the solids bed-barrel contact area. Three screws, a conventional, a barrier and a barrier-XLK design with variable melting areas are evaluated for overall melting capacity as defined by their specific output.
Evaluation of Alternative Injection Locations with Variability Consideration in an Automotive Part
Selecting proper process settings is crucial in injection molding as part quality is greatly influenced by the process conditions. The locations of the injection gate need to be decided before the mold is made. Other processing variables can be adjusted during start up; however changing the gate location at a later stage involves great cost. In this work, we analyze the effect of gate location on process consistency for an automotive part, using a multivariable optimization method called Data Envelopment Analysis (DEA).
An Examination of Field Failures of Plastic Piping System Components in Potable Water Applications
Disinfectants in potable water, such as chlorine and chlorine dioxide, can impact the performance of plastic piping system components. In this paper, field failures of plastic piping components exposed to potable water are examined. Analysis of the oxidative and mechanical initiation and propagation mechanisms leading to failure is performed. Field and laboratory samples are also compared to assess the test methodologies that are available to evaluate the impact of disinfectants on plastic piping systems.
The Interactions between TIO2 Surface and Polymer Additives
A common pigment used in many plastics application is titanium dioxide, TiO2. The pigment is a very effective light scattering inorganic oxide for the coloration and protection of plastic articles. TiO2 is also an insoluble material within a polymer matrix that has the ability to adsorb other materials within the matrix. Additionally, a TiO2 particle can catalyze the formation of chromophores from additive deactivation. This aper describes the adsorption behavior of several TiO2 materials compares the rate of chromophore formation in a polyethylene matrix compounded.
Effects of Surface Geometry of Nucleating Agents on Heterogeneous Nucleation
Ideal nucleating agents are expected to improve the cell morphology of plastics foams (i.e., higher cell densities, smaller cell size, and narrower cell size distribution) by providing heterogeneous nucleation sites. Surface geometry is one of the factors that govern the nucleating power of nucleating agents. Based on the computer simulation of a batch foaming process of polystyrene/carbon dioxide system, this paper indicates that nucleating agents having numerous crevices of small semi-conical angles, are most desirable for polymeric foaming processes.
Application of Polymer Welding Theory to Industrial Process Design
Welding time shifting expressions based upon time-temperature superposition (tTS) and hot air nozzle spacing were used to establish industrial process scale-up and design relationships for a continuous cured-in-place pipe (CIPP) liner manufacturing process. The application of tTS was successfully demonstrated to apply equally well to the commercial CIPP assembly bonding of thermoplastic polyurethane tape to a coated thermoplastic polyurethane coated felt substrate and to the hot air self-welding of a polyester needle-punched felt.
Synthesis and Characterization of a Cationic Monomer with ATRP Initiation Sites
The current coronary artery stent coating, styrene-bisobutylene- b-styrene copolymer,  has been researched and several problems arise when this coating is used. A alternative coating needs to be developed with several polymers forming from the main chain of the polymer. Several different bromination techniques have been researched to achieve the desired polymer to create the drug eluting coronary artery stent. This paper will describe the methods used.
PVC Nanocomposites – Methods of Promoting Filler Dispersion
The most widely used nanofillers for plastics are the organically modified nanoclays, in particular montmorillonite. However these clays cannot be used successfully in PVC, as they contain ammonium groups which accelerate PVC degradation. This paper considers a number of alternative nanofillers for both rigid and flexible PVC, and focuses on methods of dispersion of these fillers (involving mixing, melt blending, and polymerisation), suitable formulations to avoid thermal degradation, and potential for property enhancement.
Field Failure Analysis: Pinhole Mode of Failure of Polyolefin Pipes
Pinhole mode of polyolefin pipe failure in water distribution systems is commonly assumed to result from a sharp object impingement and attributed to inadequate installation practice. The cases of this mode of failure are investigated by direct observations of field failure combined with review of installation, service condition and stress analysis of the problem in question.
Additives for Improving Processing and Properties of Polylactic Acid
Polylactic acid (PLA) is a bioresin that is rapidly expanding into a variety of applications requiring a range of processing techniques including extrusion, calendaring, blow molding, and thermoforming. However, the low melt strength and brittle nature of the polymer provide challenges in processing and in the final product performance. We have demonstrated that the use of additives can improve processibility, melt strength and impact strength of PLA. The effect of additive type and loading levels on PLA resin properties and clarity will be presented.
Broadband Infrared Weld Strength as Compared to Other Mainstream Plastic Welding Techniques
Three welding technologies are compared using a hydrostatic burst test as the testing standard. Vibration (VW) and Hotplate (HP) welding are used as benchmarks of performance for Broadband IR (IR) welding. An injection molded three-inch diameter sphere in various materials is welded and tested for all three processes. Pressure vessel characteristics and assumptions help to determine weld tensile strength to be compared against parent material tensile strength.
Benchmarking Thermoplastic Elastomers against Traditional Rubbers in Automotive Body Mount Applications
Traditionally, automotive body mounts have consisted of a steel casing with either a natural rubber, a blend of natural rubber to increase certain properties, or Butyl. In the past several years synthetic rubber technology has expanded and thermoplastic elastomers (TPE) have been introduced. TPEs can retain the same properties of a natural rubber and reduce the cost of producing a body mount. This study comprises a comparison of thermoplastic elastomers to materials traditionally used in automotive body mount applications.
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