SPE Library

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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Conference Proceedings
Determination of Solvent Independent Interaction Parameters for the HDPE/LDPE Blend by an Improved Inverse Gas Chromatographic Approach
Liyan Zhao, Phillip Choi, May 2000
The technique of inverse gas chromatography has been used to investigate the thermodynamics of blend of high-density polyethylene (HDPE) and low-density polyethylene (LDPE) at three different concentrations and four elevated temperatures. The measured polymer-polymer Flory-Huggins interaction parameters, c23, suggest that the well-known probe dependence problem cannot be solved by simply satisfying the zero Dc criterion. The problem is mainly attributed to the use of different reference volumes in the calculations of c12, c13, and c1(23) for different solvents. By selecting a common reference volume, probe independent c23 values were obtained.
A Miscibility Study of LDPE/LLDPE Blends at Elevated Temperatures Using IGC
Maria Dulce, L.V. Silveira, Phillip Choi, May 2000
The technique of inverse gas chromatography (IGC) has been used to study the miscibility of low-density polyethylene (LDPE) with six linear low-density polyethylene (LLDPE) with different solid state density, molecular weight averages, and molecular weight distribution. In particular, the Hildebrand solubility parameters of the pure polymers were measured and used to calculate the corresponding interaction parameters ?LDPE-LLDPE at four elevated temperatures. Our results suggest that the two types of polyethylene are thermodynamically miscible in the chosen temperature range. And the miscibility behavior of LDPE/LLDPE blends seems to be insensitive to the properties of LLDPE.
Shear-Induced Crystallization in Injection Moldings of Ziegler-Natta and Metallocene Based Isotactic Polypropylenes
Y. Churdpunt, A.I. Isayev, May 2000
A comparative analysis of the shear-induced crystallization of metallocene and Ziegler-Natta based isotactic polypropylenes (i-PP's) was carried out. Numerous injection molding runs were performed and the effect of the shear-induced crystallization on the moldings was elucidated. The simulation of the injection molding process was performed using our unified crystallization model proposed earlier. The gapwise distributions of birefringence, crystallinity, spherulite size and thickness of the shear-induced crystallization layer in moldings were measured along with the mechanical properties of the moldings. The effects of processing conditions on these properties were determined. The measured values of crystallinity, spherulite size and thickness of the shear-induced crystallization layer were compared with the results obtained from the simulation of the injection molding process.
Electromagnetic Shielding and Protection against ESD by Using Stainless Steel Fibres
Johan Versieck, May 2000
Non-conductive plastics are transparent for electromagnetic radiation. This can prevent the use of plastics in housings for electronic devices. A solution to this problem is to apply a conductive coating, or to make the plastic itself conductive by adding conductive fillers. We have proven that stainless steel fibres are an excellent means to make plastic conductive for EMI (Electro Magnetic Interference) shielding purposes. Electrically insulating polymers can cause electrostatic charging/discharging (ESD) problems in some applications. Integration of stainless steel fibres in the polymer can overcome these problems by preventing charge build-up and/or by providing a safe path for discharge currents. Stainless steel fibres can be mixed in thermoplastics (injection moulding), epoxy and poly-urethane (conductive floors), paint, elastomer, rubber, ...
Computer Aided Engineering Simulation versus Actual Performance of an Automotive Structural Component
Prasanna Godbole, Joe White, Greg Hamblin, May 2000
Computer Aided Engineering (CAE) tools are able to provide powerful solutions to complex product design issues. A certain level of confidence in these solutions is assumed. However, the solutions provided are a function of several parameters: • Solver algorithm • Boundary conditions • Material properties • Fabrication process • Mesh size and type. How confident can we be in solutions from software that is performing an approximation of a real world condition based on all these variables? This paper will examine the effects of mesh size and solver method on the analysis accuracy when compared to the physical testing. To increase our confidence in these solutions, we wanted to understand the relationship between the key parameters and physical testing results. We compared various Finite Element meshing methodologies and analysis codes (structural and moldfilling) to lab tests of a Ford Ranger Pickup truck tailgate handle. Lab tests consisted of a tensile machine pulling directly on the back face of the ranger handle, which was injection molded in Nylon 6 polymer with 15% glass and 25% mineral fillings. Since material properties change with water absorption for nylon resins, all tests were conducted on dry as molded samples. Displacements and load values were documented for each test. The solutions provided from the analysis codes (while modifying element type and mesh size) were compared to the physical test results. Additional analytical lab testing was completed on the molded samples to confirm part composition, physical properties and glass orientation. Conclusions and recommendations were based on how closely the solutions matched the physical tests.
Increased Speed to Market Using CAE Simulation for Injection Molded Plastics Parts
Albert L. Duff, May 2000
The ability to cut time and cost from a molding program is a significant advantage for injection molders operating in an increasingly competitive marketplace. Warpage and other defects that show up in molded plastics parts, as well as inefficiencies in production are unacceptable. Innovation, productivity, and dedication to quality are crucial for suppliers of injection molded parts. CAE simulation software offers a competitive advantage to those who wish to eliminate inefficiencies in their operations - advantages such as shortened time to market, efficiency improvements in the use of raw materials, reduced cycle times, and optimized production efficiency and product quality.
Chemo-Rheology and Structure Development of a Solventless System for Manufacturing Electronic Pre-Pregs
Lynnette M. Dehnke, Jose M. Castro, Ming Li, L. James Lee, May 2000
Current processes used to manufacture electronic pre-pregs and laminates use solvent based systems. Solvents are environmentally unfriendly and add no value to the final product. We are developing a new solventless process, based on the concept of continuous Resin Transfer Molding or Injection Pultrusion. The first step in designing the process is to select a suitable chemical system. The viscosity of the system should be such that it allows proper impregnation at a temperature at which not much reaction takes place. To predict the required pulling force, the friction at the wall as the material solidifies needs to be truly understood. A potential resin system has been identified and its chemo-rheology and structure formation will be discussed.
Gas Absorption with Filled Polymer Systems
Lee Chen, Himamshu Sheth, Roland Kim, May 2000
This paper deals with the gas absorption behavior of polymer systems. The emphasis is on the difference between filled and unfilled polymers to explain heterogeneous nucleation in filled polymers. A Foaming process simulator has been built to study the gas absorption. It consists of a test chamber that holds the polymer samples. The chamber can be pressurized with gas up to 5,000 psi and heated up to 450°F. The gas pressure is monitored by a high-accuracy pressure transducer and recorded by a data acquisition. The amount of gas absorbed by a polymer is determined from the pressure change. A rotor applies shear to the polymer melt to investigate the shear effects. Two polymer systems were tested, HDPE with/without talc, and PVC with/without calcium carbonate. It was found that the filled polymers absorbed more gas compared to the unfilled ones. It is suggested that there is a certain amount of gas accumulated in the filler-polymer interface. This accumulated gas helps to create nucleation sites during the foaming process.
Trimellitates-Versatile Plasticizers for the Vinyl Compounder
Richard C. Adams, Steve L. Petkus, May 2000
Since the introduction of Trimellitic Anhydride by Amoco Chemicals in the late 1960s trimellitates have found their place in applications requiring greater permanence than what commercial phthalate plasticizers could bring. Trimellitate plasticizers offer today's vinyl compounder a unique combination of properties not attainable with polymeric or other monomeric plasticizers1,2. Phthalate plasticizers, long the workhorse of the industry, are efficient, process easily, impart good low temperature properties, and are well-suited for general use. Unfortunately, the phthalates can be volatile and lack the permanence needed for high temperature applications. The polymerics, which have the permanence necessary for high temperature applications, are often inefficient, difficult to process, have poor low temperature properties, and are expensive. The data presented here will demonstrate how trimellitate plasticizers bridge the performance gap between the phthalate and the polymeric plasticizers, combining the easy processing and low temperature properties of the phthalates with the low volatility and permanence of the polymerics. Compounds directed at two markets will be looked at: UL 105 °C Wire and refrigerator gasketing compound.
The Role of a Heat Affected Zone (HAZ) on Mechanical Properties in Thermally Welded Low Density Polyethylene Blown Film
Timothy E. Weston, Ian R. Harrison, May 2000
Low density polyethylene (LDPE) thin films are produced by blown film extrusion. The control of key variables during processing is important in the development of optimized microstructure and mechanical properties. Joining several extruded film pieces by thermal welding is common in industry to produce finished products. It has been reported in the literature that the welding process impacts the cold brittleness temperature of a film and weld system. This observation is confirmed in this work. There have also been reports in the literature of changes in polymer microstructure and properties adjacent to thermal welds in non-film applications such as pipe welding. This Heat Affected Zone (HAZ) has been observed here for the first time in the thin films. The size of the HAZ is shown to scale with welding temperature. Evidence correlating the size of the observed HAZ to the degree of change in cold brittleness temperature is also presented.
The Plastics Resources for Educators Program (PREP)
Timothy E. Weston, May 2000
The Plastics Resources for Educators Program (PREP) was developed as part of the National Science Foundation's Advanced Technology Education (ATE) project. The funded project was entitled, Advanced Technological Education in Plastics Engineering Technology". The PREP program aims to help establish the educational infrastructure necessary to insure the U.S. plastics industry remains internationally competitive. There are three major outcomes associated with PREP. The first outcome is the development of instructional materials including plastic processing simulators virtual laboratory instruments and an electronic textbook. The second outcome is the development of the summer plastics educators institute at UMass-Lowell. The third outcome is establishing a communication forum that will facilitate exchange between plastics and polymer educators nationally. An overview of PREP and the structure of the program will be discussed. Examples of materials available to plastics and polymer educators via the PREP Internet WebPages will also be demonstrated."
Blends of Ethylene/Styrene Interpolymers and Other Polymers: Rheology and Morphology during Processing
Teresa P. Karjala, Steve M. Hoenig, Martin J. Guest, Y. Wilson Cheung, Malcolm P. Finlayson, Brian W. Walther, Jeff R. Montanye, May 2000
Ethylene/styrene Interpolymers produced via INSITE* Technology exhibit compatibility with a wide range of polymers due to their inherent combination of olefinic and styrenic functionality. Blends of Interpolymers with polyethylene and polystyrene are discussed in terms of rheology, morphology, and observations from injection molded products. Dispersion of the minor phase is predicted by a rheological model, and these predictions are compared with the morphology of the blends.
A Catheter Designed to Give Immediate, Painless, Out-Patient Relief to BPH Sufferers
Len Czuba, May 2000
Recent developments have shown that non-invasive, focused, microwave heating of the enlarged prostate condition termed BPH or benign prostatic hyperplasia can give patients immediate and painless relief without the need for surgery and the prolonged recovery time associated with it1. This paper will describe how a urinary catheter was developed with a uniquely designed size-limiting balloon that both protects the urethra during heat treatment while also forming a biological stent. This stent opens what was swollen shut by the BPH condition and allows relief to the patient immediately after the completion of treatment rather than after a long recovery time.
Crosslinking Kinetics during Continuous Polymerization
Kal R. Sharma, May 2000
The kinetics of crosslinking polymerizations entail a complex combination of behaviors such as diffusion-controlled propagation, reaction diffusion controlled termination, volume relaxation, heterogeneous network formation, and non-constant initiator efficiency, chain depropagation and precipitation. One would like to be able to predict the mechanical properties of a material from the conditions used during the polymerization, or alternatively one would like to be able to create materials with specific properties purely through an understanding of the kinetics. A more complete understanding of the polymerization process is required before this can be achieved. We use Monte Carlo simulations to understand the characteristics such as a predisposition to hydrogen abstraction, chain length, and the ability of the system to exhibit some level of microscopic ordering, as in urethaneacrylate networks. Specifically, the effect of initiation rate on the rate of polymerization and correspondingly, the propagation and termination kinetics has been studied and aspects of the termination kinetics such as when, if ever, reaction diffusion controlled termination becomes the dominant termination mechanism have also been explored. The reaction time and yield curve generated by Monte Carlo simulations was com pared with the experimental values reported in the literature for the continuous mass polymerization of HIPS and ABS. The crosslinked polybutadiene is influential in the determination of the impact strength gloss balance.
Processing Methodology for Transparent Armor Nanocomposites
Kal R. Sharma, May 2000
The design of a single processing method to produce transparent nanocomposite is presented. This will enable the weight of the transparent armor systems to be reduced by at least 35 % against armor piercing threats relative to present systems. Transparent armors currently in use consist of soda-lime glass or borosilicate glass laminated to polycarbonate. Fabrication of large sized materials is a new feature of the new design. The chosen fabrication route is by using a twin screw non intermeshing co-rotating extruder. The cost analysis to determine production costs for 100 panels per annum is presented. The processing parameters and their effect on the strength, thermal conductivity, thermal expansion, as well as transmittance in the visual and Infra-red spectrums. The transmit wavelengths to the ratio of the particle size is used to evaluate the haze formation in the material.
Mesoscopic Simulation of Ballistic Impact Resistance of Nanocomposites
Kal R. Sharma, May 2000
The ration of areal density to level of ballistic protection is a critical factor in evaluating the ballistic impact resistance performance of silicate nanocomposites. The current goal of Army is 3.5 lb/ft2 areal density able to defeat all types of 7.62 mm bullets. Mesoscopic simulations were performed on the dynamics of the nanoparticle system. The energies absorbed by the interface, the particles, is quantitated. Comparisons are drawn between polymer polymer nanocomposites and micro composites. The polycarbonate matrix systems and exfoliated polybutadiene as the elastomeric phase was compared with the ceramic nanocomposites. The low temperature multi-axial impact strength as a function of the volume fraction of dispersion is predicted. The shift in the glass transition temperature of the polymer matrix is evaluated.
Mesoscopic Devolatilization Efficiency in Diskpack Device
Kal R. Sharma, May 2000
The design considerations of a diskpack devolatilizer cum discharger is discussed. The mixing times are compared with the time for discoloration of polymer. The mesoscopic devolatilization efficiency in diskpack device is compared with the single screw extruder devolatilizer, twin screw extruder devolatilizer, twin screw corotating non intermeshing, twin screw counter rotating intermeshing and multiple screw configurations, flash falling strand devolatilizer systems, thin filmtruder, thin film evaporator, forced circulation evaporator, falling film evaporator. The mixedness in the melt in continuous polymerization process is modeled using stochastic differential equations. The solution is obtained and a new procedure to estimate the mass transfer from the QC data is presented.
Impact Modification of Nylon 6,6 Resins with Functional Polyolefin Modifiers Based on Conventional and Metallocene Backbone Resins
N.R. Dharmarajan, T.C. Yu, J.R. Schauder, L.G. Kaufman, May 2000
This paper examines the impact toughening of nylon-6,6 resins of varying molecular weight with maleic anhydride grafted polyolefin modifiers. The modifier backbones are comprised of either conventional catalyzed ethylene propylene copolymers or metallocene catalyst based ethylene higher alpha olefin copolymers. The modifiers have maleic anhydride contents ranging from 0.5 to 1.2 wt. %; crystallinity, as measured by heat of fusion ranging from 0.7 to 6.2 J/gm; and melt flow rates ranging from 9 to 24 gm/10min. Results from the study show that modifier crystallinity has a dominant effect on impact toughening, with the amorphous modifier providing excellent low temperature toughness over a wide range of nylon-6,6 molecular weights. Higher grafting levels of maleic anhydride demonstrates no added benefit in impact toughening. A, morphological analysis using Atomic Force Microscopy, reveals the presence of nyon-6,6 sub inclusion within the modifier particles. The volume fraction of the occluded nylon, depends on the grafting level and the viscosity differences between the nylon-6,6 matrix and the functionalized modifier.
Laser Transmission Welding of Semi-Crystalline Thermoplastics-Part II: Analysis of Mechanical Performance of Welded Nylon
V.A. Kagan, G.P. Pinho, May 2000
Selecting thermoplastics for a wide industrial application (automotive, appliances, lawn & garden, power tools, etc.) strongly depends on the plastic material composition, part design, processing (molding and welding) conditions. The structure of used thermoplastics, mechanical properties and composition (reinforcements, fillers, additives, pigments, etc.) may have the greater influence and need to be characterized for optimum material selection for the laser transmission welding (LTW) application. To provide a guide to nylon based thermoplastics selection for laser transmission welding (LTW) applications we have evaluated the influence of specific material composition factors and properties, such as fiber-glass, mineral filler, impact modifier content, and color / pigment version on the Near InfraRed (NIR) transmission characteristics, including the laser wavelength (1.06 ?m). The results of an optical characterization of nylon 6 based thermoplastics are discussed in the Part I of this report to ANTEC'20001. The mechanical performance (tensile strength at room temperature conditions) of nylon welded joints was evaluated in terms of the influence of transmission laser welding technology parameters (laser power, welding speed, laser beam spot sizes, clamp pressure, etc.) and thermoplastic composition (reinforcements, fillers, additives, pigments, etc.). Technical results of this comprehensive evaluation (optical properties of nylon 6 based plastics and mechanical performance of welded joints) will assist plastic parts designers and technologists in selecting nylon based thermoplastics and developing new products using laser transmission welding (LTW) technology. The purpose of Part II of this report is to increase understanding within the plastics engineering community regarding the usefulness and possible applicability of laser transmission welding (LTW) technology for nylon made components.
Gate Land and its Effects on Gate/Cavity Pressure Loss
Bill Fierens, Sean Mertes, May 2000
In injection molded tool design, an optimum gate land has been specified as ~1.2 mm in length. This is typically given in order to optimize gate aesthetics and/or follow-up injection times. The thought process being that if the gate land is too long; gate aesthetics and part dimensions will suffer. Too short, and gate solidification will not be attainable in an efficient time frame. The data that is generated will be intended for real-world" applications and an aid to those manufacturers interested in optimization of tool design. Our goal will be to further develop the degree at which the alteration of this dimension impacts the efficiency of the process."

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