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
Wasteless Distribution Medium: A New Development for the Resin Infusion Process
T. Wassenberg, W. Michaeli, May 2000
The typical resin infusion processes like SCRIMP (Seemann Composite Resin Infusion Molding Process) require the use of a distribution medium or system to increase the impregnation speed in large parts. Normally, a substantial amount of surplus resin remains in the distribution medium and has to be disposed with the medium or remains on the part as resin rich domains. A new patented type of resin infusion process is presented, which does not produce any surplus resin waste.
Welding of Polymers Using a Diode Laser
J. Schulz, E. Haberstroh, May 2000
Welding polymers by using a diode laser is a fairly new joining method. The first industrial application is the joining of automotive keys. The process advantages are precisely defined heated zones, minimized melt flow and the realization of three dimensional weld lines. At the IKV a process analysis has been done and the influence of pigments on the weld strength has been investigated. It is possible to weld glass fibre reinforced polyamide, which is transparent for the laser beam, but appears black to the human eye.
Modeling Residual Stresses in Thermosetting Materials
Patricia Prasatya, Gregory B. McKenna, Sindee L. Simon, May 2000
The residual stresses in a composite subjected to three-dimensional constraints are calculated by extending a thermo-viscoelastic model developed previously by Simon et al. [1] to describe the time, temperature, and conversion dependence of the shear modulus for a commercial thermosetting material during cure. Experimental residual stress data as a function of cure are fit to obtain limiting values for the rubber and glassy bulk moduli. The residual stresses are then calculated as a function of cure history using the bulk moduli and the time function obtained in the thermo-viscoelastic model which include the dependence of the shift factor on temperature and conversion.
Crack Propagation in Continuous Glass Fiber/Polypropylene Composites: Matrix Microstructure Effect
M.N. Bureau, J. Denault, F. Perrin, J.I. Dickson, May 2000
The crack propagation behavior of a unidirectional continuous glass fiber/polypropylene (GF/PP) composite with two different matrix morphologies was studied. Changes in the matrix morphology obtained by varying the cooling rates during the molding process resulted in changes in: 1) the flexural strength and strain at failure using three-point bending specimens; 2) the critical strain energy release rate in mode I quasi-static crack growth using double-cantilever beam (DBC) specimens; 3) the fatigue crack growth rates at given levels of strain energy release rate in mode II fatigue crack propagation using end-notch flexure (ENF) specimens. The reduced presence of the ductile amorphous PP phase in the PP/GF composite at lower cooling rates is responsible for the reduction in mechanical performance.
Spectroscopic Studies of Ion Implanted Polycarbonate
James M. Sloan, May 2000
Ion implantation is a process by which ions are accelerated and focused at a rapid speed to a target at energies high enough to bury them just below the target's surface. These ions penetrate the sample surface and form a thin layer below the surface. Until recently this technique was mainly utilized for modification of semiconductors (1) or to improve wear characteristics in metal tooling and polymers (2,3). Now the use of ion implantation has been extended to polymers. Improvements in adhesion (4), electrical (5) and abrasion (6) have been reported. The resulting chemical effect of ion implantation in polymer systems is to increase chain scission and cross-linking., while decreasing crystallinity(7). In this study, the effects of medium energy ion implantation of boron, nitrogen and fluorine into a polycarbonate matrix was examined by Fourier transform infrared spectroscopy and UV/VIS spectroscopy. The implanted polycarbonate linkage degrades upon implantation. Further implantation leads to carbonization just below the surface of the specimens.
Optimization of Composition of Soy-Based Polyols for Rigid Polyurethane Foams
Ivan Javni, Zoran Petrovic, Wei Zhang, Andrew Guo, May 2000
Soybean oil-based polyols can be synthesized with different OH content. Higher OH number polyols display higher viscosity, which may limit their applications in foams. Adding glycerin to a polyol affects crosslinking density and homogeneity of the networks. It would be advantageous to use a lower OH content and a lower viscosity polyol and adjust the OH number with glycerin if the properties would stay the same. Apart from having lower viscosity, polyols with lower a OH number are easier to prepare. It has been shown that rigid foams based on the polyol having an OH number of 180 mg KOH/g have similar properties as those based on the polyol with an OH number of 208 mg KOH/g if the final OH number of the polyol system (polyol, crosslinker and water) is adjusted to the same value, although heat stability (onset of softening) of the former was lower.
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.
Elastomer Matrix Composites for Impact-Resistant Parts
M. Koschmieder, W. Michaeli, May 2000
The impact resistance and energy absorption capacity of most thermoset matrix composites is rather low. Use of elastomer matrix can improve the impact behavior, allowing the design of impact-resistant parts (e.g. crash elements). By using low-viscosity elastomer systems, composite parts can be produced on a commercial filament winding machine. Mechanical tests of filament wound samples show that elastomer matrix composites exhibit superior energy absorption behavior and offer a high optimization potential for impact-loaded composite parts.
Characterization of Multi-Layer Permeation Barriers Made by Microwave Plasma Polymerization
R. Dahlmann, W. Michaeli, May 2000
Plasma polymerization is a suitable process to deposit high quality permeation barrier coatings on plastics substrates. The process allows to stack several layers forming multi-layer coatings. In these studies, the permeation properties of single- and multi-layer coatings made by plasma polymerization are investigated. As a result, the oxygen transmission through multi-layers does not only depend on the structures of the single layers. Also, the arrangement of the layers shows great effect on the permeation properties.
Recycling PVB Automotive Windshield Interlayer
Robert S. Boyd, Daniel M. Sullivan, May 2000
PVB (polyvinyl butyral) windshield interlayer retains physical properties very well, owing to being effectively packaged in glass prior to recycling. However, the cost of removing all of the contaminant has precluded PVB's acceptance in many applications where it might, otherwise, have been usefully recycled. We have found that finely pulverizing the scrap, with its attendant residues, allows melt-process manufacture of products meeting automotive requirements for vibration damping, tensile strength, tear resistance, and flexibility, over a wide range of temperatures.
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.
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.
Adding Value to Rotational Moldings with Color and Special Effects
Nick Henwood, May 2000
This paper reviews the different ways of adding color in rotational molding and provides technical and economic arguments for each method. The effects of pigment incorporation on base material properties are discussed and the importance of factors such as pigment type, pigment loading and method of mixing are examined in relation to material processing, physical properties and the aesthetics of the final rotomolded part. The use of special effects such as stone and antique look colors to give further value enhancement is discussed.
Some Reasons Not to Use Multi-Cavity (>4) Tools
John W. Bozzelli, May 2000
Injection molding continues to be the preferred plastic process for making large quantities of plastic parts. The goal is to make identical parts. When parts are not identical problems develop, not just in performance but also in assembly. The trend toward more complex parts, coupled with demanding tolerances continues to challenge processors in pursuit of the goal of identical parts. Reasons against the trend for high cavitation molds are proposed.
Polymer Melt Flow Behavior in the Coinjection Molding Process
K.T. Nguyen, E. Turcott, A. Derdouri, D. Ait Messaoudz, B. Sanschagrin, B.A. Salanton, K.A. Koppi, May 2000
An experimental study of the co-injection molding process was carried out. The fingering instability due to the difference in viscosities of the two materials gave rise to early breakthrough of the core material and non- uniform skin layer thickness. The core material was also used as tracer material for flow visualization of the injection molding process. The V formation near the wall as well as the mushroom effect, previously predicted, was observed.
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.
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