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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Effect of Process Parameters on Viscoelastic Properties and Hoop Stress in Micro Injection Molded Parts
Measuring the properties of micromolded parts has always been a challenge, but modified testing procedures may solve this problem. Tensile properties using a modified shear punch test and dynamic mechanical properties with modified torsion test fixture. The measured tensile strength increased significantly with packing pressure and melt temperature whereas mold temperature and injection velocities had little effect of these properties. Moreover, the strength of the micromolded parts was also greater than the values reported for standard tensile tests, thereby suggesting that skin effects influence the mechanical properties of thin-wall parts. The torsional properties of a micromold part, however, were similar to those for standard test specimens and increased with injection velocity and packing pressure.
Effect of Processing and Aspect Ratio on the Percolation Threshold of Exfoliated Graphite-Polypropylene Nanocomposites
Polypropylene based nanocomposites reinforced with exfoliated graphite nano-platelets (~10nm thickness, ~1mm diameter, < 5$/lb, Young’s Modulus ~1060Gpa) were fabricated using melt mixing. Initially, the nanoplatelets are mechanically dispersed into the polymer melt i.e., a twin-screw extruder, and then the composites are made using injection and compression molding. The effects that processing, aspect ratio and dispersion of graphite in the polymer matrix have on the electrical conductivity and percolation threshold of the nanocomposites are explored.
Co-Extrusion of Films for Medical and Other Packaging Applications
In this study the co-extrusion and use of a cyclicalpha olefin and metallocene polyethylene for medical and packaging applications was investigated. The combination of these materials are cost competitive and provides the opportunities for an environmentally friendly disposal and possible recycling. A film with alternating polyethylene, cyclic- alpha olefin, and polyethylene layers was coextruded with the use of three extruders leading into a multi-layer feedblock. The film was tested for oxygen and water permeability, tensile properties, falling dart impact strength, and tear strength. An economic analysis of the fabrication of the film for the use in medical and packaging applications was also constructed. The study demonstrated that the co-extrusion of a cyclo-olefin and metallocene polyethylene provides an opportunity for environmental means of disposal and a means of fabrication.
Comparison of Predicted and Experimental Filling of Micromolded Parts
Differences in simulation results for micromolded and macromolded parts are significant. Variations in the predicted results arise due to the governing equations used for flow analysis. Micromolded parts produced from two materials and using a range of processing conditions were compared with results of filling simulations. Critical results were the fill pressures, weld line strength and relative shear stresses developed in the parts. Fill pressures were obtained from the machine and optical birefringence was used to compare actual with predicted shear stress. These were then compared with the theoretical and experimental results. Differences were accounted for in terms of governing equations and assumptions used in the analysis.
The Solubility of CO2 in Polypropylene: Comparison of Various EOS Models
In order to get reliable solubility data, the swollen volume due to the dissolved gas is required. The swollen volume is typically estimated by an equation of state (EOS). In this paper three different EOSs, i.e., Simha- Somcynsky (SS) EOS, Sanchez-Lacombe (SL) EOS, and Perturbed-Chain SAFT (PC-SAFT) EOS, were applied in the polymer/gas mixture system. The apparent solubility was obtained using a magnetic suspension balance (MSB). The approaches based on the SS, SL and PC-SAFT EOS were proposed to predict the swelling behavior of polymer/gas mixtures for the purpose of correlation on the apparent solubility. Finally, the solubility of CO2 in PP melt was determined based on the three EOSs.
Effects of Particle Modification on the Fatigue Damage Progress in Polynanomeric Matrix Composite Laminates
The effects of the incorporation of layered clay, alumina, and titanium dioxide on the tension-tension fatigue damage progress in composite laminates were investigated by characterization of microcrack growth. The modification of the matrix systems of these composites, defined as polynanomeric matrix composites, was shown to significantly affect the fatigue damage progress. It was found that 5phr clay modification significantly improved the fatigue damage properties of the composite laminates. The mechanics of this effect were revealed by Scanning Electron Microscopy (SEM) observations in sub-micron and nano scales.
Rheological Studies of Polymers under High Pressure Carbon Dioxide
The viscosities of carbon dioxide-impregnated polymers in the literature are currently limited to high shear rates using capillary or extrusion rheometers. This paper uses a rotational rheometer to report data on the zero-shear viscosity of carbon dioxide-saturated polymers. The viscosity drop of a polybutene oil is one and half orders of magnitude at 35°C and 6 MPa, while the zero-shear viscosity of poly(dimethylsiloxane) (PDMS) drops half of an order of magnitude at 30°C and 3 MPa. Efforts are ongoing to measure the CO2- plasticized viscosity of polystyrene melt.
Load-Deflection Characteristics of Plated Thermoplastics
The theoretical and experimental load-deflection behaviors of plated and non-plated polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) samples were compared. In the first part of the study, the experimental 3-point bending load-deflection behavior of the non-plated PC/ABS samples was determined and was compared to calculated theoretical predictions. In the second part of the study, the equivalent width method was used to predict the theoretical load-deflection behavior of the plated PC/ABS samples. These predictions were compared to the experimental three point load-deflection curves. The study demonstrated that the plating did have an extremely significant effect on the actual load-deflection behavior of the PC/ABS samples and that the equivalent width technique did predict the change in stiffness, but tended to over predict stiffness. Additional tests are being conducted to determine the creep behavior of the PC/ABS and plated PC/ABS samples.
Integrity Management of Plastic Pipelines
The area of integrity management of pipelines is one of growing interest. In many pipeline applications, the aging infrastructure is posing a challenge for pipeline owners and operators. Particularly in applications involving potentially hazardous materials this is an issue that needs to be approached proactively. The Natural Gas Distribution industry is one falling into this category and new Pipeline Integrity Management Regulations are currently being considered by the federal Department of Transportation. Separate from the pending regulations, Gas Utilities are also proactively examining the integrity of plastic pipeline systems. This paper reviews the changing approach and pending legislation for managing the integrity of plastic distribution system materials. A general approach to examining the functional integrity of plastic piping systems is presented. A specific case study examining the integrity of an exhumed-from-service (natural gas distribution) plastic piping material is presented along with comparisons of projected pipeline functional integrity versus actual field service performance. It is concluded that, although the specific form of pending regulations for pipeline integrity management (PIM) is not known, some effective tools and techniques for assessing pipeline functional integrity, a subset of the overall PIM approach, are currently available.
Effect of Particle Size on the Efficiency of a Moisture Scavenging Additive
The effect of fibers and fillers is well understood in the plastics industry, where additive particle size has been shown to affect a variety of part properties. However, the result of integrating moisture scavenging additives within plastic materials is relatively unknown. This experiment will examine how particle size affects the efficiency of a moisture scavenging additive in a variety of different carrier materials. Numerous mechanical properties such as tensile strength, impact strength, viscosity, hardness, and specific gravity, among others, will be tested to evaluate the results of this analysis.
Pultrusion and Mechanical Characterization of GFRP Composite Sandwich Panels
This paper presents mechanical properties under static loads of 3.5 inch thick composite sandwich panels which were manufactured through pultrusion process. The objective of the present work is to demonstrate an automated pultrusion process for producing composite sandwich panels which results in optimal mechanical performance while minimizing unit weight and production cost. To achieve the above objective, the composite sandwich panels were designed, pultruded, tested and evaluated for their mechanical performance enhancement in relation to panels manufactured from VARTM process. Preliminary results have demonstrated that pultruded panels present significant advantages over VARTM panels, including 36% increase in tensile strength and stiffness, 87- 97% increase in bending stiffness at panel level, 8 -20% reduction in area weight, and est. 46% reduction in material and production costs.
Method for the Ensuring the Efficient Design of Plastic Products
It is easy to talk about bringing a new product into production in an efficient manner; it is another thing to actually accomplish it. This presentation shows a method for bringing a new plastic product: ON TIME, ON COST, and ON BUDGET.It deals with who is responsible for what, phases and miles stones, activities, and critical path. Diagrams are given that show a clear way on how to accomplish objectives by following the step-by-step approach. When viewed in it’s entirety, it looks so simple and straightforward, and that one is left with the thought: why don’t we do this?It takes commitment and discipline by every one involved, from the top level to the newest participant. The method has been developed over years of experience by the presenter who can testify that when truly applied the objective is achieved. The principals apply whether you are in a large or very small organization. At the very least the viewer will be left with an overall insight as to what it takes to bring a new plastic product to fruition.
PBA-Based Extrusion Foaming of HDPE/Wood-Fiber Composites
It has been established that the production of foamed structure in plastic/wood-fiber composites (PWC) is overwhelmingly dominated by the gaseous emissions/volatiles released by the wood-fiber. By adopting effective processing strategies, the role of these volatile emissions on foam morphology of PWC can be largely suppressed. Improving the cell structure of PWC could further improve their properties such as impact strength, toughness, ductility and machinability, which would increase their utilities. PWC foamed with a chemical blowing agent (CBA) do not have a fine cell structure as a higher processing temperature is needed to decompose the CBA. This problem can be addressed if a physical blowing agent (PBA) is used.
Indoor Weathering Characterization, and Quantification, of Extremely Non Homogenous Indoor Environments, and Application to Risk Assessment of Indoor Products
Large expanses of the planet are being converted to indoor environments. At first glance this may appear to reduce the burgeoning work load of the Reliability Engineer; however, these environments are every thing but uniform as the name indoor would imply. Variations in the light sources, intensities, humidity, and types of materials each have a uniqueness which must be understood. The paper will describe the unique challenges with the indoor environment, applicable testing practices, and procedure for applying the results.
A Magnetorheological Study of Multi-Walled Carbon Nanotube Dispersions
The magnetorheological properties of multi-walled carbon nanotube (MWCNT)/mineral oil dispersions were studied using a parallel plate rheometer. 0.5, 1.5 and 2.53 vol% nanotubes dispersions were investigated. Strain sweep, frequency sweep, magneto sweep and steady shear test were conducted in various magnetic fields. Storage modulus G', loss modulus G complex viscosity ?* and dynamic yield stress ?y increased with increasing magnetic field strength which was partially attributed to the increasing degree of alignment of nanotubes in a stronger magnetic field. The G' and G" of MWCNT/mineral oil dispersions were scaled with nanotube volume fraction ? by a power-law. The shear thinning behavior of MWCNT/mo dispersions followed the Ostwald-de Waele or power law."
PVC Stabilization Using Lead Stabilizers and Zeoliten Co-Stabilizer
Zeolites are known to be effective co-stabilizers for PVC formulations. In this paper, the authors discuss Advera® zeolite co-stabilizers produced by the PQ Corporation, their properties and their use in lead stabilized PVC formulations for rigid and flexible applications (window gaskets, window profiles). Thermal stability results for these two production PVC formulations with various zeolite loadings partially replacing the lead stabilizer blend components will be discussed.Specifically, the performance of commercial zeolite, Advera® 401P was studied. It was found that, depending on the ingredients in the PVC formulations, 15 to 35% of the lead stabilizer could be replaced by the zeolite co-stabilizer. PVC formulations with the zeolite had the same or better thermal stability performance. Since Advera zeolites are less expensive and have a significantly lower specific gravity than the lead stabilizers they replace, a significant costs savings can be realized. Lead stabilizers are still being used extensively in the Far East, therefore, the Advera zeolite co-stabilizers produced by PQ Corporation plants in Thailand and South Korea were used in this study.
Transparent Electrostatic Dissipitave Materials for Drug Delivery Devices
Transparent, electrostatic dissipative (ESD) materials have been designed for use in brachytherapy and inhalation therapy applications. Design of the material as an inherently electrostatic dissipative product through the development of a polymeric system rather than a topical or additive treatment results in permanent ESD characteristics that may provide improved efficiency in drug delivery. This paper focuses on the ESD performance of an acrylic-based material that provides good optical transparency as well as good ESD performance. Unlike ESD materials that are produced with typical additives, the material also demonstrates good ESD performance at high and low humidity levels and after repeated washing with water.
Foaming Polystyrene with a Mixture of CO2 and Ethanol
Use of mixtures of blowing agents in thermoplastic foam extrusion has been an industrial practice for a long time. However it has gained renewed interest in the past few years due to the introduction of difficult-to-process alternative gases, targeted as potential replacement for the banned ozone-depleting blowing agents. Reasons for blending physical foaming agents (PFA) are numerous. The incentives may be economical, environmental or technical. With respect to that latter factor, blending suitable PFA’s is often regarded as providing a better control of processing conditions. For example, a specific PFA could be selected for its inflation performance and blended with other co-blowing agents chosen for their stabilizing role. Although considerable amount of work has been done in that area, very little information has been disclosed in open literature.Carbon dioxide (CO2) has been reported as an interesting candidate for low-density polystyrene (PS) foaming, although the required concentrations are associated with high processing pressure due to the low solubility of the gas. Thus stable processing conditions are difficult to achieve. This work studies the effect of blending CO2 with ethanol (EtOH) as a co-blowing agent for PS foaming. Extrusion foaming performance of this mixture will be discussed, with respect to its solubility (i.e. degassing conditions) and rheological behavior. The function of each blowing agent during the process will be analyzed with respect to the plasticization, nucleation, expansion and stabilization phases. Attention will also be paid to the interaction involving the two PFA components.
Numerical and Experimental Investigation of the Effect of Mandrel Motion on Extruded Parison Thickness
The use of simulation software to predict the thickness distribution in a blow molded part is becoming more widespread, thus saving considerable time and money in the product development process. For extrusion blow molding simulations, the ability to obtain an accurate final thickness prediction depends on starting with the correct parison thickness distribution. An extrusion simulation tool that incorporates the effects of parison programming, die swell and parison sag due to gravity is required to predict the correct parison thickness distribution. In this study, we compare the parison volume predicted by a finite element-based extrusion model with experimental measurements. The effects of different parison programs are investigated. The goal is to determine the level of accuracy and reliability of the extrusion model for predicting parison thickness.
Glass Transition Effects in Immiscible Polymer Blends
Bulk polymer properties are altered when they are blended with an immiscible component. A glassy polymer, polymethylmethacrylate (PMMA) was blended with a semi-crystalline one, polypropylene (PP) via melt processing. The effect of blend structure and physical interactions between components on the Tg of the glassy component were studied. Modulated Differential Scanning Calorimetry (MDSC) was used to analyze the glass transition. Even though the components are immiscible, significant correlations between blend composition and glass transition temperatures were observed. Models which could explain this behavior are discussed.
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