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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Comparison of N2 and CO2 in Extrusion Foaming of Wood-Fiber Composites
Producing cellular wood-fiber/plastic composite (WPC) with physical blowing agents (PBA) offers unique advantages over chemical blowing agents (CBA). This paper compares the foaming behaviors of two environmentally benign PBAs, namely N2 and CO2, to help understand PBA-based foaming mechanisms in WPC. This understanding will help in making proper choices about PBAs and foam processing parameters.
High Heat Ductile (HHD) Copolymers by Reactive Extrusion
A blend of two polycarbonate copolymers, high-heat poly(ester-carbonate) (PEC) and polycarbonate-polydimethylsiloxane copolymer (PC-PDMS) provided an opaque, pearlescent blend. However, when a transesterification catalyst was used, the blend becomes miscible and translucent/transparent. The high-heat, ductile (HHD) materials were analyzed for a range of properties including optics, rheology, heat performance, flame retardance, and mechanical properties. The hydrolytic stability of the HHD materials was also measured by comparing the ductility of the blends before and after autoclaving.
Extrusion Foaming Behaviors of PET with CO2
This paper investigates the extrusion foaming behaviors of Polyethyleneterephthalate (PET) blown with supercritical CO2. The evolution of the foam's morphology once it exited from the die was recorded using a CCD camera and also characterized by SEM. Microcellular PET foams can be prepared by optimizing the PET properties as well as the processing conditions.
Effect of Moisture Absorption on the Properties of Clay-Reinforced Polypropylene Nanocomposites
The behavior of two polypropylene nanocomposites when immersed in distilled water or sea water at four different temperatures was studied and compared with that of neat PP. The nanocomposites showed a higher water diffusion rate and equilibrium moisture content. Nevertheless, because of their superior initial mechanical properties, after 42 days exposure they were still equivalent to unexposed PP. X-ray diffraction and infrared spectroscopy were applied to characterize the surfaces of the exposed specimens.
Phase Separation in Thermotropic Liquid Crystalline Polymer/Polycarbonate Blends under Shear
The effect of shear on the temporal development of phase separation in thermotropic liquid crystalline polymer (LCP)/polycarbonate (PC) blends was examined. Experiments were performed using a polarized-light microscope, equipped with a shearing hot stage. Phase separation, with and without shear, in blends containing 50 wt % LCP were analyzed. The results showed that the speed and amount of phase separation increased when shear was applied.
Foaming Dynamics of Immiscible Polymer Blends
To better understand the underlying mechanisms of immiscible blend polystyrene/poly (methyl methacrylate) (PS/PMMA) foaming, a simple bilayer representation is examined. Visual observation of batch foaming of this system is conducted and a quenching method is used to study foams with different bubble growth time. These help understand the effects of blend morphology on foaming in a more quantitative way.
Rheology of Heterogeneous Polymer Melts
Heterogeneous polymers represent an important class of plastics that comprise polymer blends, alloys, and fiber or mineral filled plastics. The rheology of these melts is dominated by the transient morphology that is produced during fabrication into finished products. Standard laboratory rheological tests do not take into account morphology. Combined measurements of a capillary viscometer and controlled stress rotational rheometer can provide a better understanding of the processing behavior of these complex rheological plastics
Cluster Performance Measurement: A Case-Study of Plastic Clusters in the Czech Republic
The topic of clusters has emerged as a crucial idea in competitiveness and economic development in the last years. This paper shows and discusses (basing on concrete plastic cluster in the Czech Republic) possible approaches to the cluster performance measurement. There are analyzed problems related to the performance measurement and suggested suitable performance measures. This case-study also shows the possibilities for mutual cooperation and ways in which the research results can be transferred into working practice.
Prediction of Continuous Kneader Reactor Processes from Batch Data
Batch trials were performed on a kneader reactor where a bulk co-polymerization was carried out. Polymerization conversion, viscosity build, reaction kinetics, and heat transfer calculations were performed using the experimental data from the batch trials. A continuous process was proposed for this bulk copolymerization and the models and results from the batch trials were used in designing the continuous process. Predictions of the continuous process using the batch trial data are compared to the actual continuous process, with a focus on polymer conversion, heat transfer, and torque prediction.
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.
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