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
Structure Development in Melt Processing Polypropylene, Polypropylene-EPM Blends and TPEs
Fibers have been melt spun from polypropylene and its blends with ethylene propylene rubber, as well as polypropylene based thermoplastic elastomers under various conditions. The spinline stresses as well as kinematics have been measured. The fibers have been structurally characterized using wide angle x-ray diffraction and birefringence and the results interpreted.
Transient Start-Up Flow in a Modular Co-Rotating Twin-Screw Extruder
A model for flow start-up of a Newtonian liquid in an initially empty modular co-rotating twin screw extruder is developed. The changes of length of fill in front of the die and kneading disc block elements and output flow rate with time were predicted for various modular screw configurations. Experiments were also carried out on a laboratory modular machine with windows to verify the predictions. Generally, good agreement with the flow analysis was found.
A Comparative Study of Fiber Breakage in a Buss Kneader, Modular Co-Rotating and Counter-Rotating Twin Screw Extruders
The breakage of glass fibers was measured for several different types of continuous mixers including (i) Buss Kneader (ii) modular intermeshing co-rotating twin screw extruder (iii) modular intermeshing counter-rotating twin screw extruder. Comparisons are made using different screw configurations, loadings, different feeding ports and mixing elements. Downstream feeding of glass fibers and milder screw configuration favor less breakage of glass fibers.
Ultrasonic Thickness Gauge for Multi-Layer Plastic Fuel Tanks
A newly developed instrument, the Echometer measures the thickness of a barrier layer in multilayer polyethylene fuel tanks. Measurement by conventional pulse-echo ultrasound fails for thin barriers due to the large and highly frequency-dependent attenuation in polyethylene. The present instrument instead uses tone-burst excitation. Echo arrival time determines barrier depth, and frequency of minimum amplitude determines barrier thickness. Similar techniques may be applied to other layered plastic structures.
Orientation Determination Using Birefringence and Spectroscopic Techniques
Techniques for the measurement of orientation of biaxially oriented films, sheets, and shapes using birefringence measurements based on oblique incidence of a polarized multiwavelength beam and FTIR spectroscopy in both transmission and reflection modes are presented. It is shown that sufficiently precise values can be obtained for biaxial birefringences and orientation functions, and that these techniques can be used for monitoring orientation processes as well as to control the quality of oriented articles.
Efficient Coping with Production Breakdowns Using Knowledge-Base Approach
Injection molding product quality is affected by many process parameters. The usual trouble-shooting procedures suggest a list of possible corrective actions for each potential failure of a product, without taking into account possible side effects. There is one optimal corrective action, leading to the most stable process and product quality. This paper presents a methodology that helps the operator to select the most efficient corrective action, using Knowledge-Base (K.B.) approach, relying on a Y-shape matrix (failure-cause-solution) with theoretical rules and practical statistics.
Photostabilization of Polycarbonate-Styrenic Blends
A new HALS technology has been developed which provides for improved light stabilization of pigmented PC-ABS blends. Significant improvements in color stability and impact strength retention have been observed for PC-ABS systems subjected to accelerated weathering xenon arc test conditions. The new HALS technology is non-interacting with the PC-styrenic blend during melt phase extrusion compounding, as observed by capillary rheometry measurements of the stabilized polymers.
Modeling of Rheological Behavior of Immiscible Polymer Blends Undergoing High Deformation Flows
Non linear rheology of a mixture of two immiscible viscoelastic fluids undergoing high deformation flow was considered. Using Grmela's approach of compatibility of dynamics with thermodynamics, we derived a set of highly non-linear governing equations that take into account particles breakup, coalescence and the time evolution of the complex interface between the two mixture components. The proposed model recovers previous models such as Doi-Otha, Grmela and Ait-Kadi and Lee and Park models.
Failure Analysis Case Studies, Part I: Effect of Processing Conditions and Part Design
In this paper, some case studies are presented to illustrate the effect of processing/assembly conditions and part design on product failure. Fractography was intensely used in these investigations. Nevertheless, mechanical analysis was occasionally used. The first case illustrates the role of assembly conditions in product failure. The second case shows the effect of part design. The third case describes the combined contribution of processing/assembly conditions and part design in product failure.
Maintaining the Thermal Balance Core to Cavity: The Key to Cooling Efficiency
Achieving parts with maximum dimensional stability coupled with minimum cycle times, is a goal of most molders. Previous studies have shown that a majority of heat contained in the molded part is removed through the core of a mold. Application of high strength, high thermal conductivity copper alloys to core, cavity, and gate areas, has led to some revelations. These data shed new light on the effect of change in temperature vs. change in thermal conductivity.
Mechanism of Organotin Stabilization of Poly(Vinyl Chloride). 4. PVC Stabilization by Alkyltin Alkyl Mercaptopropionates
The stabilization effect of alkyltin 2-ethylhexyl mercaptopropionates was studied by the measurement of color change on heating a PVC formulation.
Bubble Dynamics in Viscous Shears Flows
The growth of a gas bubble in a viscous liquid in shear and extensional flows has been studied toward understanding polymer devolatilization. The experimental work was carried out in a Couette apparatus, which operates under vacuum. Air bubbles, which were formed, deformed and grown in a low molecular weight polyisobutylene, were photographed under shear. The experimental growth results indicate that the growth rate of a slender bubble increases as the shear rate increases and as the pressure decreases. These results confirm the existing theory, however they show that simple shear flow is much less efficient than simple extensional flow.
How to Work with the Trade Press - Eight Keys to Getting Your Releases and Papers Published
Nothing can be more rewarding (or frustrating) than working with a trade magazine's editorial department. A solid working relationship with the trade press enables individuals and companies to deliver their business and technological news, ideas, accomplishments and opinions to the masses in a timely manner and with relative ease. A basic understanding of how trade press editors perform their duties and how editorial departments function allows business marketers to achieve their goals. What follows are eight key points that will help you put your best foot forward in the trade press.
Sheet Extrusion of Thermoformers
Thermoformers can achieve many advantages by producing sheet in house. Sheet extrusion systems for in-line thermoforming and off line use are available in a wide range of sizes to suit almost any consumer or industrial thermoformed product application. The benefits of in-house sheet extrusion will be reviewed. Thick cut to length, thin roll stock, and in-line applications will be discussed. The methods of determining the size of the required sheet extrusion line and the capital equipment requirements will be used to determine the cost per pound of extruded sheet to enable you to calculate your savings.
The Development of a Resin Coated Sand Tooling Process for the Manufacture of Plastic Components
This paper describes the application of foundry sand moulding technology to the development of a rapid and low cost injection-moulding tooling system. An assessment of the sand / binder foundry moulding processes is presented which considers the requirements of the injection moulding process. Rapid Prototyping (RP) is used to provide a master pattern for transferring the geometry to the tool. Suitable formulations of sand, binder, hardener and curing conditions for tooling application are then discussed.
Deformation and Fracture of Polymer Silicate Layer Nanocomposites
The deformation and fracture behaviour of polyamide-6/silicate nanocomposites are studied. With increasing clay content the modulus increases much more substantially than can be achieved with micron-sized clay particles, but the fracture toughness drops significantly. The micromechanisms of fracture are relatable to the microstructure of these materials. The matrix is capable of a surprising amount of shear plasticity. Rubber modification is effective in producing more crack tip damage which increases the toughness of these composites.
High Performance Structured Polymer Barrier Films
Polypropylene (PP) was functionalized with maleic anhydride (MAH) and diethyl maleate (DEM) in a twin-screw extruder. The functionalized PPs were mixed with a 80/20 wt./wt.% blends of polypropylene and ethylene-vinyl alcohol copolymer (EVOH) and the extruded films were stretched at the exit of the flat die. The effect of the functionalized PPs and stretching on PP/EVOH blend were investigated. Morphological analysis along with mechanical and thermomechanical analysis showed that PP-g-DEM is a good candidate for tailoring materials with enhanced barrier properties.
Overmolding and Co-Extruding Melt-Processible Rubber on Rigid Substrates
This paper will review the use of melt-processible rubber (MPR) in overmolding and co-extrusion with various rigid plastic substrates. Looking to improve product quality and develop new applications, plastics engineers are turning to MPR technology to cost-effectively add the high performance properties and warm, soft feel of rubber to their products. MPR exhibits superior resistance to weather, oils, chemicals, gasoline, and UV light, and is processed on conventional plastics equipment, which provides potential cost savings.
Effect of the Skin/Core Ratio on the Flow Behaviour during Co-Injection Moulding
The effect of the core/skin ratio on the overall flow behaviour in the co-injection molding process was studied. A 7.6x16.4x0.7 cm3 rectangular plaque was moulded using a 150-ton Engel co-injection machine. ABS was used both for the skin and core material and PC were used only as the skin material. For visualization purposes, a black pigment was added to the core material. The results are discussed in terms of the relative viscosity, injection speed, melt and mould temperatures.
Thermal Stability of Polyurethanes Based on Vegetable Oils
A series of polyurethanes from polyols derived from soybean, corn, safflower, sunflower, peanut, olive, canola and castor oil were prepared and their thermal stability in air and nitrogen assessed by thermogravimetric analysis, FTIR and GC/MS. Oil based polyurethanes generally had better initial thermal stability in air than the polypropylene oxide based polyurethane, while the latter was better in nitrogen. If a higher conversion is taken as the criterion of stability then all oil based polyurethanes have better thermals stability both in air and in nitrogen.
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