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Conference Proceedings
A Preliminary Investigation into the Use of Wood Fibers as a Filler in the Rotational Molding of Polyethylene
G.W.G. McDowell, J.F. Orr, J. Kissick, R.J. Crawford, May 2001
There has been no known work carried out on the use of wood fibers as a filler in the Rotational Molding (herein also referred to as rotomolding) of Polyethylene. It is reported though that the extrusion industry has noticed a 100% increase in wood fiber profiles over the past two years. (1) It is only a matter of time before this diversity of materials will find itself being used in Rotational Molding. This paper presents investigative results of the characteristics of the molded parts in terms of molding conditions, percentages of wood fiber used and the type and size of wood used. Potential for novel product design and the uses for the wood/ plastic composite will also be discussed.
Natural Fiber Reinforced Polypropylene Composites – an Approach on Thermoforming Processing
Octávio Pimenta Reis Neto, Nestor Pedro Giacomini, May 2001
This work has been performed at Mercedes-Benz of Brazil in a partnership with its suppliers aiming the replacement of fiberglass in polypropylene matrix composites by natural fiber reinforcements. The process that has been chosen for this purpose was Vacuum-forming. This choice took into account the large application that this technique represents in the company's commercial products. The results expected for this new material is cost and weight reduction besides the friendly environmental aspect that this change introduces. Jute fiber reinforced polypropylene sheets at constant thickness and fiber content were prepared in order to evaluate the feasibility of the application. The preliminary results have shown that this material has a great potential of application because of the low fiber costs.
Experimental and Analytical Verification of Plastics Material Models for Automotive Crashworthiness Applications
Stephen M. Pitrof, Michael C. Lee, May 2001
Plastics are widely used in automotive component applications, such as instrument panels, door panels, consoles and pillar garnishes. These components are subject to government-mandated impact tests for occupant safety. To overcome the traditional cut-and-try methods in designing automotive components, advanced CAE (Computer Aided Engineering)/FEA (Finite Element Analysis) analytical methodologies have been used to assist the design and manufacturing of the desired components. The objective of this paper is to investigate the effects of material model and impact speed of the drop weight on the response of an injection-molded plastic knee bolster part under a designed drop-silo impact test. FEA simulations on the knee bolster were conducted using both LS-DYNA3D and ABAQUS/Explicit. The analytical results are compared to the experimental data from the drop-silo impact test. Several engineering plastic materials are evaluated, and correlation is quantified. Observations are made with respect to materials characterization experiments, material constitutive models within the analyses, and general test and modeling procedures. Suggestions are made for improved correlation for the future.
The Effect of PP-MA and PP-GMA as Compatibilizers on Polypropylene/Nylon 6 Blends
A. Tedesco, R.V. Barbosa, S.M.B. Nachtigall, R.S. Mauler, May 2001
Blends of polypropylene (PP) and nylon can combine good properties, however both polymer are incompatible. PP functionalized with maleic anhydride (PP-MA) has been used as compatibilizer for this system and the PP functionalized with glycidyl methacrylate (PP-GMA) should be a good alternative due to reactivity of the epoxy group with -NH2 and -COOH group. Blends of PP/PP- MA or PP-GMA/Nylon 6 were prepared using 30% of nylon (Ny6). The effect of the compatibilizer were evaluated by DSC, SEM micrograph and mechanical properties. The analysis indicate that PP modified with MA show the best compatibilizing effect in these systems.
Compatibilized Polypropylene/Polyamide Blends
S.M.B. Nachtigall, A.H.O. Felix, R.S. Mauler, May 2001
When properly compatibilized PP/PA blends can offer a wide range of desirable characteristics, combining properties of both components. The aim of this work is to compare the effectiveness of the compatibilizing effects of different modified polyolefins on the properties of PP/PA blends. The blends were constituted by a PP matrix and they were obtained in a mixer chamber. PP modified with maleic anhydride and vinyltriethoxysilane (PP-MA and PP-VTES) and EPR modified with maleic anhydride (EPR-MA) were employed as compatibilizing agents. Products were characterized by SEM and DSC. Melt flow indexes and mechanical properties of the blends were determined.
Use of Pyrolised Oil Shale as Filler in Polyolefins
R.V. Barbosa, R.S. Mauler, R. Baumhardt-Neto, S.M.B. Nachtigall, C. Gorga, May 2001
The pyrolysed oil shale originating from the pyrolysis of the bituminous rock was used as filler in mixture with poly(ethylene-co-vinyl acetate) (EVA) and high density polyethylene (HDPE). The effects of this addition were compared with the ones obtained with different vinyl acetate content and size of pyrolysed oil shale particle. The compounds were prepared on a Haake equipped with mixing head Rheomix, at 180°C. Samples were compression-molded and tensile testing ware performed on an Instron apparatus using a crosshead speed of 10 mm/min. Tension curves of samples were obtained. These curves showed the possibility utilization the pyrolysed oil shale without damaging the mechanical properties of the compounds, for low concentration of pyrolysed oil shale (1-5 wt%) if the particle of pyrolised oil shale is lower than 270 mesh. Besides of this behavior it was observed that the vinyl content of polymer is important to enhance the mechanical properties in the compound. Compounds of poly(ethylene-co-vynil acetate)/pyrolysed oil shale and high density polyethylene were obtained with concentration of pyrolysed oil shale up to 30%. The behavior of these materials were evaluated taking into account the concentration and the size of the used particle. It was observed that particles with the smaller diameters showed best effects on the mechanical properties of the final material if the concentration of the pyrolised oil shale used up 5% wt%. The mechanical properties, differential scanning calorimetry, and scanning electron microscopy results and dynamic mechanical thermal analysis are discussed.
Degradation Mechanisms of Thermoplastic Polyurethane Resins
Philip H. Patterson, James M. Sloan, Alex J. Hsieh, May 2001
The use of polymeric materials for transparent, lightweight armor has been of great interest to the U.S. Army for a number of years. Field items such as goggles, lens, face and windshields are currently manufactured using advanced polymeric plastics. These items are designed with polymers that provide excellent optical clarity, rugged abrasion resistance, and high ballistic impact strength. However, as with any organic polymer system, these materials are susceptible to degradation over time when exposed to various environmental (i.e. sunlight, moisture, temperature) conditions. This structural degradation (1-4) will eventually comprise the original integrity of the materials' desired properties. In this study, the impact of accelerated weathering upon newly developed polyurethane based thermoplastic materials was investigated. A fluorescent ultraviolet (UV)/condensation weathering tester was selected for the exposure study. The materials were characterized by UV/VIS spectroscopy and FT-IR spectroscopy. The results reveal that the urethane linkages undergo a scission reaction upon UV exposure drastically affecting the mechanical properties of the material. Furthermore, these urethane scissions produce a yellowing of the polyurethane which can inhibit its use where optical clarity in important.
Diffusion Studies in Polymerized Poly (Methyl Methacrylate) Nanocomposites by FT-IR
James M. Sloan, Alex Hsieh, May 2001
Polymer-layered silicate nanocomposites have attracted enormous interest both in scientific research and potential commercial applications mainly due to the potential technological applications. The silicates used in these nanocomposites consist of stacked individual platelets with a dimension typically on the order of 1 - 100 nm in length and 1 nm in thickness. These nanoscale structures provide the resultant material with an improvement in properties, which include abrasion resistance, and mechanical properties. In this paper, we report the improvement in barrier properties when a PMMA/Clay nanocomposite is synthesized. This increase in barrier properties is attributed to a successful dispersion of the clays in the polymer matrix. Reports have shown that properties depend upon the extent of intercalation, and in many cases exfoliation are desired to achieve the properties. Comparison of the effect of two different types of clays, montmorillonite and a synthetic clay, fluorohectorite, on the transport properties was studied. In each case an improvement in barrier properties was observed.
Multi-Component Blends Based on Polyamide 6 and Styrenic Polymers
S.H. Jafari, P. Pötschke, M. Stephan, G. Pompe, H. Warth, H. Alberts, May 2001
Reactive and non-reactive blends of polyamide 6 (PA6) with different styrenic based polymers [acrylonitrile-butadiene-styrene terpolymer (ABS) and styrene-acrylonitrile copolymer (SAN)] were made on a twin screw extruder under similar processing conditions and blend composition. Effect of reactive compatibilizer on thermal, morphological and rheological properties were studied using DSC, SEM and a parallel plate oscillation rheometer. It was found that the reactive blends have lower crystallization rate and nucleation ability but higher melt viscosity with co-continuous morphology, whereas the uncompatibilized blends have higher crystallization rate and nucleation ability but lower melt viscosity and form disperse and/or coarse co-continuous morphology.
Integrated CAE Analysis for Powder Injection Molding: Filling, Packing and Cooling Stages
S.T. Chung, T.G. Kang, S.J. Park, Y.S. Kwon, H.K. Ahn, T. Yoon, May 2001
Powder Injection Molding (PIM) is a manufacturing technology for the mass production of small and complex metal or ceramic parts. PIM is composed of mixing, injection molding, debinding and sintering processes. We have developed a numerical simulation program for the injection molding process of PIM parts, PIMflow, taking account of the peculiar rheological behavior of powder/binder mixture, most notably the apparent slip phenomena at the mold wall. The coupled analysis between the filling, packing and cooling stages was performed because the viscosity and slip phenomena of powder/binder mixture highly depend on temperature. Using the example of electronic package, this paper demonstrates the importance of this issue.
A Portable on-Line Rheometer
Ming-Wan Young, David B. Todd, May 2001
The Helical Barrel Rheometer (HBR™) is a device capable of utilizing viscosity monitoring of a melt slipstream from the process (reactor or extruder), or independently, determining the viscometric behavior utilizing solid feed. It does not require flow or torque measurement and solely relies on pressure drop and shaft speed to generate the viscosity data as a function of shear rates. The design principles of the current HBR™ unit have been focused on its portability, flexibility and versatility, yet it remains industrially rugged. It has been demonstrated that the HBR™ is a unique device in measuring viscosity of filled polymeric systems in a flow field more representative of process equipment as opposed to capillary devices. Other uses beyond viscometric measurement are also described.
Substitution of Metallic Insert Joints by Two-Shot-Molding
Axel Tome, Gottfried W. Ehrenstein, May 2001
Threaded inserts in brass or in plastic show static and dynamic load-limits comparable to economic joints with self-tapping screws. A newly developed approach that is based on molding in a local area of reinforced plastic into a non-reinforced plastic component using multi-component-injection-molding was investigated. In this reinforced area a self-tapping screw is assembled. This joining technology could substitute the implementation of an insert after molding. In this paper, the joint performance in dependence of the interfacial strength will be shown in comparison to inserts made from brass and plastic as well as to self-tapping screws. In particular, the static load-limits and the clamp force, which is time dependent, will be discussed.
Mechanical Behavior and Crack Propagation in Injection-Molded Polyamide 6/Clay Nanocomposites
Martin N. Bureau, J. Denault, Franck Glowacz, May 2001
The crystalline structure and mechanical behavior of injection-molded polyamide 6 (PA6) reinforced with 2 wt.% polymer-intercalated nano-layered silicate (montmorillonite) is studied. X-ray diffraction and differential scanning calorimetry show that the presence of layered silicate in PA6 nanocomposites lead to the formation of a different crystalline structure when compared with unmodified PA6. Considerably improved tensile strength and modulus obtained from the nano-layered silicates while maintaining the ductility of the PA6 matrix indicate that strong matrix-filler ionic interactions and very high specific area and aspect ratio of the polymer intercalated-layered silicates characterized this nanocomposite. In the conditioned state, while an elasto-plastic fracture with extensive tearing is observed in unmodified PA6, a linear-elastic fracture is observed in the PA6 nanocomposite.
Optical Constants Determination of Absorbing Polymer Film with the Prism Wave-Guide Coupler
Tao Liu, Robert J. Samuels, May 2001
The prism wave-guide coupler has been limited to measuring the refractive index of transparent or weakly absorbing thin films. However, this study shows that it is possible to extract the complex refractive index (both the refractive index and the extinction coefficient) of highly absorbing films from a careful analysis of the internally reflected light intensity from the prism-wave-guide coupler. This method has been used to obtain the three-dimensional complex refractive indices of two polymer films, spin coated polyaniline (PANI) and 3M black vinyl electrical tape, using a modified Metricon PC 2010 prism wave-guide coupler.
Investigations into Rotational Moulding of Short Fibre Reinforced Thermoset Resins
Simon Bickerton, Roy J. Crawford, May 2001
The addition of reinforcing fibres, or fillers, to liquid thermosets significantly alters the rheological behaviour of such resins, drastically increasing viscosity. In order to successfully mould these materials a good understanding of their rheological behaviour is required. A simple numerical model is developed, predicting evolution of the resin cure reaction, and resulting in-mould rheological, and flow behaviour. Qualitative comparisons are made to initial moulding experiments completed with neat, and wood fibre filled polyester resins. Moderate additions of fibre were found to improve part quality due to the increase in initial viscosity, while a practical limit was reached above which excessive fibre clustering occurred.
Inventions in Polymers: It Takes Teamwork to Make a Successful Business
P.M. Subramanian, May 2001
The last five decades have seen the explosive growth of synthetic polymers. Innumerable types of polymers and their derivatives designed for specific properties and applications have been invented and developed. Fundamental to such growth are the creative discoveries of several scientists and innovators. Converting these brilliant discoveries into major business successes have taken the concerted efforts of a large number of a second set of inventors and innovators. While the primary inventors have been well recognized, often, the latter scientists and innovators, without whose contributions these products and processes would not have become large successful businesses, are relatively unknown. As examples, Teflon*, super-tough nylon, and sretch-blow-molding of PET bottles and the teamwork that made these into significant businesses, will be discussed here.
Experimental Investigation of Slip in Plug-Assisted Thermoforming
P. Collins, P. Martin, E. Harkin-Jones, Denis Laroche, May 2001
Surface friction is known to play a vital role in determining product wall thickness distribution during plug-assisted thermoforming. In this study this behavior has been investigated by carrying out experimental tests to measure both the static and dynamic coefficients of friction acting between typical plug materials (Delrin, syntactic foam and aluminum) and polypropylene (PP) sheet at elevated temperatures. Plug only tests were also conducted to investigate the effect of plug temperature on wall thickness distribution. Results showed that values of coefficient of friction varied from 0.13 up to 0.72 depending on sheet temperature and the combination of materials tested. Plug temperature was also shown to be very important, with a temperature of 90°C showing the greatest slip during plugging. It was concluded that friction at the plug-sheet interface was temperature dependant and further work is required to verify these initial observations.
Inventions, Patents and Innovations: A Beneficial Symbiosis - How I Learned to Stop Worrying and Love Patents"
Tai-Sam Choo, May 2001
Alter exploring the role of patents in encouraging disclosure of inventions as a significant stimulus to technological developments and innovations, this presentation will also probe how patents can protect commercial investments and provide a competitive advantage in global economy. Also presented will be certain practical considerations and tips on how to prepare and obtain patents others would envy." To this end the presentation will highlight major differences between the U.S. patent system and others will review important recent changes in legal requirements (with particular emphases on rule changes resulting from the enactment of the American Inventors Protection Act) and will examine common pitfalls to avoid. Where appropriate the patents relating to the innovations advanced by other speakers in Fundamentals Forum on Invention and Innovation will be featured as illustrations."
A Model and Parameter Formulation of Stress-Induced Crystallization Kinetics of Polymers
Jianxin Guo, Kwabena A. Narh, May 2001
A stress-induced crystallization model for semicrystalline plastics is proposed based on the theory that stress induced orientation of molecules and chains increase the melting point of the plastics, and hence, the supercooling which is the driving force for crystallization. By assuming that the effect of stress on crystallization is only by increasing the equilibrium melting point, the basic quiescent state crystallization equation can be directly applied to model stress-induced crystallization kinetics. The model predicts the most prominent features of stress-induced crystallization. The main advantage of the model is that the parameters in the quiescent state crystallization model do not change. Consequently, the parameters in the equilibrium melting temperature shift model are easy to determine, and the unknown constants are kept to a minimum.
Optimization in Process Control for Uniform Quality of the Optical Components
M. Rahman, N.R. Schott, May 2001
Part weight, dimensions, shrinkage and birefringence are a few important measurable parameters that are used to define the quality of plastic optical components. The quality of a plastic part can be assured by determining the proper and optimized set of injection molding process variables. Online cavity pressure data as a function of time for a dual cavity optical mold were analyzed with an equation of state for an Ising fluid for establishing the PVT relationship. The PVT data were then used in an empirical model to determine the optimized set of process variables for the expected quality of a part.


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