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
Processing and Properties of Polymer Nano-Composites
Hua Wang, Mark Elkovitch, L. James Lee, Kurt W. Koelling, May 2000
Polymer nano-composites are prepared by melt intercalation in this study. Nano-clay is mixed with either a polymer or polymer blends by twin screw extrusion. The clay-spacing in the composites is measured by X-ray Diffraction (XRD). The morphology of the composites and its development during the extrusion process are observed by SEM. Rheological behavior of the composites are measured. It is found that the clay spacing and composite morphology are influenced by the concentration of the nano-clay and the type of polymer used. The addition of the nano-clay can greatly increase the viscosity of the polymer when there is strong interaction. If such polymer/nano-clay mixture is used as the matrix phase, it would lead to improved dispersion and distribution of the minor phase in the polymer blends. The effect of nano-clay on polymers and polymer blends is also compared with Kaolin clay under the same experimental conditions.
Effects of Impact Modifiers on the Properties of Rigid PVC/Wood-Fiber Composites
Fatih Mengeloglu, Laurent M. Matuana, Julie A. King, May 2000
This study examined the effects of impact modifier types and addition levels on the mechanical properties of rigid PVC/wood-fiber composites. The formulations of the composites were modified by incorporating crosslinked (all acrylic and methacrylate butadiene styrene) and uncrosslinked (chlorinated polyethylene) impact modifiers at various concentrations. Mixtures of PVC, wood-fibers, impact modifiers, and other processing additives were dry-blended using a high-intensity mixer. The dry-blended compounds were extruded, compression molded, and tested for tensile and Izod impact strength properties. Analysis of variance (ANOVA) was used to discern the effects of impact modification on the mechanical properties of the composites. The experimental results indicated that the impact resistance of rigid PVC/wood-fiber composites depends strongly on the type and content of impact modifier. With the proper choice of modifier type and concentration, the impact strength of rigid PVC/wood fiber composites can be significantly improved without degrading the tensile properties. Methacrylate butadiene styrene and all acrylic modifiers performed in a similar manner and were more effective in improving the impact resistance of rigid PVC/wood-fiber composites than the chlorinated polyethylene modifier.
The Effect of Tie-Layers on Optical Properties of Coextruded Multilayer Films
Dean A. Zimmerman, May 2000
The tie-layer is a critical component of multilayer films and can effect the optical properties of the overall film structure. This paper evaluates various tie-layers for their effect on optical properties of the film. The see-through and contact clarity of the film is explained based on a combination of the physical properties of the tie-layer resin and the effect of the interfacial region on flow instability. Rheology of the interfacial region is discussed based on controlled experiments simulating the reaction that occurs during multilayer extrusion and shows that the shear stress and complex viscosity can be used to estimate the see-through clarity in multilayer coextruded films.
Optimizing the High Speed Machining Process for Hardened Steel Molds
Staffan Gunnarsson, Berne Nilsson, May 2000
Constantly reduced product life cycles and increasing product variety compels the moldmaker to cut down on long production times especially in mold and die making. Electrical Discharge Machining (EDM) has been the conventional finishing technique for generating complex free form surfaces. However, the EDM process also generates a brittle, recast layer, which is often detrimental to mold performance. High speed machining technology of today offers an economical alternative to EDM, which does not significantly deteriorate mold surface properties. This paper will evaluate the benefits of a high-speed machined mold compared with conventional manufacturing techniques. It will also investigate the effects of different cutting parameters, in an attempt to optimize the high speed machining process.
Flow Behavior of Sparsely Branched Metallocene-Catalyzed Polyethylenes
Phillip J. Doerpinghaus, Sujan E. Bin Wadud, Donald G. Baird, May 2000
The dramatic effect of chain architecture on the melt flow behavior of polyethylenes is well established. The advent of metallocene and other constrained-geometry catalysts now allows the precise control of molecular weight, branch content, and branch distribution. In the present study, the rheological responses of three different metallocene-catalyzed polyethylenes are analyzed. Despite similarities in their shear properties, the differences in transient extensional viscosities can be attributed to the presence of sparse long-chain branches and/or high molecular weight fractions. Melt fracture observations as well as full-field flow birefringence measurements are collected to further corroborate this idea.
A New Impact Modifier for Toughening Clear APET
Edward J. Troy, Anthony C. Fazey, Evan Crook, May 2000
Polymers, as well as glasses, exhibit physical 'aging' which leads to embrittlement. Impact modifier additives counteract this embrittlement. In clear polymer systems, such as amorphous polyethylene terephthalate [APET], blends with typical commercial impact modifiers show a significant loss of optical clarity. The work presented here, based on a new impact modifier additive, shows that embrittlement of APET can be counteracted without significant loss of optical clarity.
Fractography of ABS
Hiromi Kita, Masatoshi Higuchi, Atsushi Miura, May 2000
Fractograpy of different types of ABS has been studied in static and cyclic loading at different ambient temperature. The effects of repeated loading, notch, grades, loading level and ambient temperature on the fracture surfaces have been discussed on the basis of the phenomena of striations, tear lines, fracture origin and stress whitening patterns.
Using CMM Data to Quantify Sink Marks
Kris Horton, Mitchel Keil, Paul Engelmann, David Lyth, Michael Monfore, May 2000
For years decisions have been made about the acceptability of a molded part based upon subjective assessment of attributes such as sink marks. The mechanisms that cause sink are well documented. Yet sink marks continue to be a leading cause of rejected products. This research focused on developing a repeatable measurement technique for objectively quantifying the depth of sink marks. Following preliminary investigation, a coordinate measuring machine (CMM) was employed.
Plastics Failure Due to Oxidative Degradation in Processing and Service
Myer Ezrin, Amanda Zepke, John Helwig, Gary Lavigne, Mark Dudley, May 2000
Aliphatic hydrocarbon polymers, such as PE, PP and copolymers thereof are particularly susceptible to oxidative degradation to lower molecular weight in processing and in service. The result is reduced strength, embrittlement, and shorter service life. High temperature required for melt processing is a major factor in oxidative degradation. Decrease in oxidative induction time or induction temperature measured by differential scanning calorimetry are practical methods of monitoring the effect. Formulations need sufficient antioxidant to be protected during processing and in service.
Nanocomposites: The Importance of Processing
H. Ryan Dennis, Douglas L. Hunter, Dohoon Chang, Sangyup Kim, James L. White, Jae Whan Cho, Donald R. Paul, May 2000
Nanocomposites have been studied for nearly 50 years, but few references deal with the importance of how the organoclay was processed into the plastic of choice. Many articles focus on the importance of the chemistry used to modify the surface of the clay, usually montmorillonite, without including the role of processing. This paper demonstrates the importance of both the chemistry of the clay surface and how the clay was processed into the thermoplastic. Two different clay treatments were added to polyamide 6 using four different types of extruders with multiple screw designs.
Injection Molding and Physical Aging Properties of Amorphous Poly(ethylene terephthalate)
A. Bhakkad, E.A. Lofgren, S.A. Jabarin, May 2000
Physical aging characteristics of amorphous poly(ethylene terephthalate) have been evaluated in relationship to several important injection molding parameters. For these investigations; packing pressure, melt temperature, and mold temperature were each varied individually, with other conditions held constant. Aging studies were performed at three different storage temperatures, using the molded specimens. Changes in density, notched Izod impact strength, and enthalpy of relaxation were monitored as functions of aging times. Time temperature superposition analyses were performed using experimental data and master curves were constructed. Results give predictions of lower temperature long term enthalpies of relaxation and notched Izod impact strength properties.
The Effects of Compatibilizers, Polyamide-6 Grade, and Filler Type on the Properties of TPO/Polyamide-6 Blends
Luca Saggese, Carol M.F. Barry, Stephen A. Orroth, May 2000
This study examined the effect of compatibilizers, polyamide-6 grade, fillers, and injection rate on the properties of polyamide-6/TPO blends. The addition of polyamide-6 to TPO raised tensile and flexural moduli, and consequently, DTUL and scratch resistance; however, it adversely affected Izod impact strength. While a di-terminated polyamide-6 (NH2 capped) exhibited better properties than a non-terminated material (COOH end), wollastonite fillers had a greater influence on the blend properties. Compatibilizers primarily impacted elongation, impact strength, and scratch resistance whereas high injection velocities increased impact strength and scratch resistance.
Recycled Fiberglass Composite as a Reinforcing Filler in Post-Consumer Recycled HDPE Plastic Lumber
S.D. George, S.H. Dillman, May 2000
Post-consumer high-density polyethylene is commonly used to make lumber products, but such products are substantially less stiff than wood lumber. Using a two factor full factorial experimental design, the effects on tensile, flexural and impact properties of adding ground recycled fiberglass composite in combination with wood flour to high density polyethylene were investigated. The addition of ground fiberglass composite was found to significantly increase tensile and flexural modulus, while decreasing impact strength. Ground fiberglass was found to have a greater stiffening effect than wood flour, but wood flour had no significant effect on impact strength.
Polymer Near-Surface Behavior Characterized by Reflectometry and Complementary Techniques
Mark D. Foster, May 2000
Engineering the near-surface structure and properties of materials requires characterization tools that are sensitive to that structure and those properties. X-ray and neutron reflectometry provide exquisite depth resolution for near surface structure. These tools are most powerful, however, when combined with lower resolution complementary techniques that give the depth profile directly or with techniques which resolve the structure laterally. Reflectometry's capabilities are demonstrated by a study of the interfacial segregation of star-branched polymers in a blend of linear and star chains. Dynamic secondary ion mass spectroscopy and nuclear reaction analysis are used as complementary probes.
A Case Study on the Application of Finite Element Modeling in Ultrasonic Resonator Design
Thomas R. Kirkland, James A. Kosterman, May 2000
This paper discusses the steps taken to develop an ultrasonic horn from concept through final design. Finite element modeling was used to discover the optimum geometry, which in turn resulted in superior welding results.
In Line Monitoring of Poly(ethylene vinyl acetate) Extrusion Process Using Fiber Optic Raman Spectroscopy
M. Dhamdhere, B. Deshpande, P. Patil, M.G. Hansen, May 2000
The extrusion of molten poly(ethylene vinyl acetate) (EVA) was studied using in-line fiber optic Raman spectroscopy. The properties monitored were the content of vinyl acetate (VA) in the random copolymer and the melt index of various grades. Results are presented for independent multivariate regression of VA content and melt index values. This study presents an important development of in-line monitoring techniques that have evolved from off-line bench top measurements.
Extrusion Characterization of Ethylene/Styrene Interpolymers
Kurt A. Koppi, Mark A. Spalding, Mike D. Cassiday, Kevin R. Hughes, Teresa P. Karjala, Steve R. Betso, Charles F. Diehl, May 2000
An investigation of the extrusion performance of ethylene/styrene Interpolymers was performed. These Interpolymers are pseudo-random copolymers of ethylene and styrene synthesized via INSITE* Technology, Dow's proprietary, single-site, constrained-geometry catalyst technology (1,2). Extrusion characteristics such as output rate, specific energy consumption, and extrudate temperature were measured as a function of screw design and processing conditions.
Compatibilization of PP/HDPE Blends: Morphology and Interfacial Tension
Adriana Martinelli Catelli de Souza, Nicole Raymonde Demarquette, May 2000
In this paper the compatibilization of polypropylene (PP)/high-density polyethylene (HDPE) blend was studied through morphological and interfacial tension analysis. Three types of compatibilizers were tested: ethylene-propylene-diene copolymer (EPDM), ethylene-vinylacetate copolymer (EVA) and styrene-ethylene/ butylene-styrene triblock copolymer (SEBS). The morphology of the blends was studied by Scanning Electron Microscopy. The interfacial tension between the components of the blends was evaluated using small amplitude oscillatory shear analysis. Emulsion curves relating the average radius of the dispersed phase and the interfacial tension to the concentration of compatibilizer added to the blend were obtained. It was shown that EPDM was more efficient as an emulsifier for PP/HDPE blend than EVA and SEBS.
New Thermoplastic Resin Compounds Utilizing Highly Efficient Conductive Filler System
Niraj Patel, May 2000
During the last few years, there has been a rapid growth of electronic equipments within industrial, commercial and domestic environments. This has led to a need to control the problem of static build-up and discharge during the manufacture, distribution and usage of products containing microprocessors. In addition, often it is necessary to contain electromagnetic radiation (EMI), which can inhibit normal operation of microprocessor containing devices. The issue of static control and discharge is also important in areas such as prevention of ignition of flammable fluids and handling of powder (to prevent dust explosion). Commercial plastic materials are insulators and hence, are often modified using conductive materials like carbon fibers to provide static dissipation and EMI shielding. This paper describes highly efficient ESD / inherently shielding engineering thermoplastic resins which can be used in a broad variety of applications. A binder was identified in this study that enhanced shielding effectiveness and reduced resisitivty of resin systems with which it was incompatible.
Gas Barrier Behavior of Syndiotactic Polystyrene
K. Hodge, S. Nazarenko, G. Capaccio, May 2000
The effect of crystallinity on barrier properties of syndiotactic polystyrene (s-PS) was studied. The crystallinity was induced in s-PS by cold crystallization and crystallization from the melt. Two thermally induced crystalline forms ? and ? were observed in all crystallized samples as well as the presence of ?-mesomorphic phase in the samples cold crystallized at lower temperatures. The oxygen permeability and diffusion occurred at finite rates in the loose a hexagonal crystalline phase while it was negligible in better-packed ? orthorhombic phase. The permeability and diffusion of oxygen increased with an increase of the amount of a ordered phase while the solubility decreased, remaining, however, still soluble for oxygen even at 100%.
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