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
Rheology, Processing and Electrical Properties of Multiwall Carbon Nanotube/Polypropylene Nanocomposites
Semen B. Kharchenko, Kalman B. Migler, Jack F. Douglas, Jan Obrzut, Eric A. Grulke, May 2004
Dispersal of a relatively small concentration (about 1 % volume fraction) of multiwall carbon nanotubes (MWNT) into polypropylene (PP) is found to cause large and complex changes in nanocomposite transport properties. Specifically, both the shear viscosity ? (?) and electrical conductivity ? (?) of the MWNT nanocomposites decrease strongly with shear rate and, moreover, these dispersions exhibit impressively large and negative normal stresses. Additionally, when extruded, MWNT nanocomposites shrink rather than swell. We associate these flow-induced property changes with the formation of non-equilibrium, percolated nanotube network structures.
The Development of Structure in a Melt Blended Polypropylene Organoclay Nanocomposite
M.D. Read, L. Liu, J.D. Harris, R.R. Samson, May 2004
The development of structure was evaluated for a melt blended polypropylene organoclay nanocomposite on a co-rotating intermeshing twin-screw extruder. The development of structure was investigated by evaluating the degree of dispersion of the clay platelets as a function of distance (or shear history) down the length of a specially designed clam-shell extruder. The dispersion was characterized by optical and TEM microscopy, x-ray diffraction, and mechanical property testing. The results show the development of structure from the initial large agglomerates to the final mixture of exfoliated and intercalated platelets.
Characterization of Polypropylene Composites at Low Micro-and Nano- Filler Content
Anita Vaxman, Noru Tsalic, Daphne Benderly, Rotem Shalom, Moshe Narkis, May 2004
Polypropylene/nanoclay (PP/clay) and polypropylene (PP) containing traditional mineral fillers (talc, mica, GF and wollastonite) are used in a comparative study encompassing structure, mechanical, rheological and thermal properties. At equal filler loadings, PP/clay nanocomposites exhibit a higher flexural modulus and melt viscosity, and enhanced thermal stability, as compared to the microcomposites studied. The structural differences between nano and microcomposites are demonstrated by rheometry, microscopy and thermal stability. Significant differences in behavior result from the much higher surface area of delaminated plates and their higher aspect ratio.
Properties of UV Curable Acrylate Nanocomposite Coatings
Fawn M. Uhl, Prashanth Davuluri, Shing-Chung Wong, Dean C. Webster, May 2004
Recent advances in functional nanocomposites have created new frontiers in research for radiation-curable organic coatings making use of nanocomposite technology. Little is understood on incorporating organomodified clays and its curing kinetics in UV curable polymers. UV curable films were reinforced with organically modified montmorillonite (MMT). Preliminary results showed that acrylate nanocomposite coatings exhibited intercalated structures and enhanced properties. Increases in tensile strength and Young's modulus were observed. Cure time to a tack free film and conversion monitored by real time infrared spectroscopy (RTIR) were reported.
Structure and Properties of Polyurethane/Clay Nanocomposites and Foams
Xia Cao, L. James Lee, May 2004
Polyurethane (PU)/Clay nanocomposites are synthesized using surface treated montmorillonite clays bearing different functionalities. Effects of various functional groups and clay/monomer mixing sequence on the reaction and clay dispersion of polyurethane are investigated by X-ray diffraction and transmission electron microscopy. Silicate layers of organoclay can be exfoliated in the PU matrix by adding hydroxyl and organotin functional groups on the clay surface. Furthermore, PU nanocomposite foams are also prepared with surface treated clays. A smaller cell size and higher cell density can be achieved compared to pure PU foam.
Mechanical Properties of Bisphenol-A Polycarbonate via Controlled Crystallization and Orientation in the Presence of Supercritical Carbon Dioxide
Xianbo Hu, Alan J. Lesser, May 2004
Our previous research on fiber drawing in the presence of supercritical carbon dioxide (SCCO2) has shown that the control of orientation and crystallization is of one of the critical factors in the development of fibers with high tenacity and stiffness. Thus identifying materials that allow for such control is necessary for fundamental studies. The extremely low thermal-induced crystallization rate of bisphenol-A polycarbonate (PC) makes it an ideal candidate for this kind of research. In this article, an effective method is used to control the orientation and crystallization of PC separately by using SCCO2. The influence of orientation, crystallization, and addition of nano-scale clays are studied with regard to the mechanical properties of the material.
Mechanical Properties of Injection Molded Glass Fiber Reinforced PC/ABS with PC Oligomer
Susumu Takashima, Satoko Baba, Hiroyuki Hamada, Machiko Mizoguchi, Takashi Kuriyama, May 2004
In this study, the effect of PC-oligomer on mechanical properties and internal structure of injection molded glass-fiber reinforced PC/ABS was investigated. The mechanical properties of PC/ABS with PC-oligomer were lower and the difference became larger with increasing GF content. However, the internal structure was different from the surface to the middle layer through thickness direction. It is thought that this difference in structure and the dispersion of GF affected the mechanical properties of the composites.
Creep Prediction Using the Non-Linear Strain Energy Equivalence Theory
Jennifer K. Lynch, Kenneth Van Ness, Thomas J. Nosker, Richard W. Renfree, May 2004
The Non-Linear Strain Energy Equivalence Theory, a semi-empirical model, is utilized to predict long-term creep from short-term compressive stress-strain experiments conducted at different strain rates. Stress-strain experiments in uniaxial compression are performed at strain rates of 3 and 0.03 %/minute to predict creep behavior and stress-strain data at several strain rates for an immiscible polymer blend of recycled fractional melt flow high-density polyethylene and recycled polystyrene. The creep behavior is predicted up to 50 years at stress levels of 400 and 800 psi.
Surface Damage of Polymers in Nanoscale
Janet Wong, Hung-Jue Sue, Kai-Yang Zeng, Robert Li, Yiu-Wing Mai, May 2004
Surface damage of polymers in the nanometer-range is examined and results correlated with material characteristics and surface roughness of epoxies. Under a constant loading and constant scratch rate testing condition, surface roughness plays little or no role in surface damage formed during the course of this study. Material characteristics influence the damage occurred in terms of variations in elastic recovery, damage pattern and damage mechanism. The variations in scratch head geometry, which, in turn, lead to the variations in magnitude of stress and stress field distribution, give rise to various scratch features on the polymer.
Determination of Scratch Behaviour of Molded Plastics
Hiromi Kita, Maki Makoto, May 2004
Scratch behavior in several types of plastics have been investigated in order to develop scratch test method for plastics. The effects of scratching conditions such as scratch speed and normal load on scratch behavior have been discussed. The scratch behavior was classified into three modes (i.e. ploughing, wedge formation and cutting) based on the vertical scratch tip displacement and the horizontal load during the scratch process and scratched surface observation. A concept of scratch behavior evaluation is described by using mapping technique and some of the typical results are introduced.
Surface Characterization of Rigid Rod Polymers
Sarah E. Morgan, Nick Malkovich, Chang K. Hong, Sonya D. Benson, Charles L. McCormick, Gordon C. Cannon, May 2004
A novel family of processable rigid rod polymers with outstanding mechanical properties has been recently introduced (Parmax® Self Reinforced Polymers (SRPs)). These materials, among other applications, are of interest in the field of high strength and stiffness, MRI-transparent implants driving an interest in their surface properties. Molded articles were fabricated from rigid rod polymers and surfaces were treated by mechanical and chemical modification. Surface properties were evaluated via contact angle measurements and AFM. In general, these aromatic rigid rod materials demonstrate high hydrophobicity. Surface modification techniques provided increased hydrophilicity of the surfaces. Interaction with biological molecules is reported.
Transmission of Tribological Measurement Values from the Model-System to the Part-System
Rolf Künkel, Gottfried W. Ehrenstein, May 2004
Tribological measurement values represent system- properties. Therefore they are not directly transferable from the model-system pin-disc to the bearing technology. However, these values can be adjusted through qualified correlation. Basic differences in geometrical, kinematical and thermal relations between the two systems influence the friction- and wear-mechanisms.A focal point is the tribological analysis of different systems as pin / disc (thermoplastic / Steel) and bearing / shaft (thermoplastic bearing / steel shaft). According to online-measurements and calculations, statements can be evaluated about the transferability of the results from the different systems and about the mathematical coherences of a possible correlation. The consideration of the heat development resulting out of friction in both systems, which has an important influence on the transferability of the tribological properties from the model-system to the part-system, is the main focus.
Artificial Weathering Effects on the Scratch Resistance of Automotive Instrument Panel Thermoplastic Polyolefins (TPO)
Beth M. Wichterman, Dottie A. Britz, Rose A. Ryntz, May 2004
This study focused on evaluating the effects of artificial weathering (per a filtered automotive interior Xenon weathering method) on the scratch resistance of two thermoplastic polyolefins (TPO-A and TPO-B). The scratch resistance evaluated using 5-Finger and Scratch-O was significantly lower after short artificial weathering exposures for both TPOs. The coefficient of friction determined using a Slido method increased as the scratch resistance decreased. Microhardness increased and indentation depth decreased with artificial weathering.
Surface Properties of Amphipathic Films of Natural and Synthetic Polymers
Chang K. Hong, Sonya D. Benson, Gordon C. Cannon, Charles L. McCormick, Sarah E. Morgan, May 2004
The surface properties of thin film amphipathic proteins (hydrophobins) and Pluronic® (PEO-PPO-PEO) polymers are investigated to evaluate surface lubricity and adhesion on molded polymer surfaces. Hydrophobins are fungal proteins that self-assemble at hydrophilic-hydrophobic interfaces into amphipathic films and Pluronics are nonionic amphiphilic surfactants. Because of their unique properties, they are of interest as models for potential biomedical and pharmaceutical applications. We have studied the self-assembly behavior of hydrophobins and Pluronic® polymers on hydrophobic polymer surfaces and examined the surface hydrophobicity and the lubrication properties.
Polyurethane-Clay Nanocomposites via Bulk-Polymerization Methods
Asim Pattanayak, Sadhan C. Jana, May 2004
In this study, polyurethane nanocomposites of organically modified clay were synthesized by bulk-polymerization methods and their properties characterized. The polymerization methods took into account the possibility of formation of clay tethered polymer chains via reactions between isocyanate groups in the chains of prepolymer and chain extended polymers with the hydroxyl groups on organic modifier of clay. The thermal and mechanical properties of the resultant materials were evaluated as function of the method of nanocomposites preparation. As high as 110% increase in modulus and 170% increase in tensile strength were observed with only 5wt% organically treated clay particles. The method based on chain-extended polymers performed better than the method based on prepolymer.
Investigation of the Microscopic Origins of the Torque and Normal Force Responses of Glassy Polymers
Anny Flory, Gregory B. McKenna, May 2004
Under the assumption that glassy polymers are incompressible, the mechanical response of a cylinder of viscoelastic material below the glass transition temperature to a torsional deformation consists of a torque response and a normal force response along the axis of the cylinder. In performing stress relaxation experiments on poly(n-alkyl methacrylate)s, the normal force required to keep the constant deformation is compressive and large. Here we examine the microscopic origins of the nonlinear response functions. We consider the influence of the secondary, sub-vitreous ? relaxation on the normal force response. This is done by performing experiments on poly(methyl methacrylate) (PMMA) and poly(ethyl methacrylate) (PEMA) which both exhibit a ? peak in the loss modulus as a function of temperature located at the same temperature of 10 °C and having about the same intensity. A surprising result is that although the torque response for the PMMA is 50% higher than for the PEMA, the normal force response for the PMMA is 20% lower than the normal force response of the PEMA at the experimental temperatures of 45 °C and 30 °C.
Use of Thermography in Craze Growth and Plastic Zone Studies of Polycarbonate
Rahul Patki, Paul J. Phillips, Bing Yang, Peter K. Liaw, May 2004
The occurrence of a plastic deformation zone ahead of the crack tip in fracture of thin films and sheets of polycarbonate has been reported by several authors. This presentation will report the use of a high-speed thermographic imaging technique for studying the temperature rise at the crack tip as well as the shape and temperature distribution of the plastic zone in polycarbonate sheets. The technique was used to monitor craze and crack growth in compact tension tests. New trends in the growth of the plastic zone and the crack propagation mechanism were observed.
Hysteresis Loss of Polymeric Materials: Finding of New Dimensionless Parameters
Kamal K. Kar, Anil K. Bhowmick, Joshua U. Otaigbe, May 2004
An in-depth experimental and theoretical study of many important factors governing the hysteresis loss of rubber vulcanizates having variation of loading of carbon black, silica, clay, resin, and curatives is carried out over a wide range of strain, strain rate/frequency and temperature. Experimental results reveal that the hysteresis loss depends on the heat generation of rubber vulcanizates, specific heat, thermal conductivity, Young's modulus, filler loading, structure and surface area of the filler, temperature difference between application temperature and glass transition temperature, frequency, temperature difference between wall and environment, stress, and stroke amplitude. To confirm the above statement, the hysteresis loss data are analyzed by dimensionless parameters developed by using both of Buckingham pi-method and Rayleigh method. Based on the analysis, an equation is developed in which hysteresis loss of rubber vulcanizates is expressed in terms of the operating conditions and material properties of elastomers.
Compaction and Dilatation Effects during the Plastic Deformation of Glassy Polymers
Christian G'Sell, Jean-Michel Jean-Romain, Abdesselam Dahoun, Jean-Marie Hiver, May 2004
Samples of poly(methyl methacrylate) - PMMA for short - were subjected to uniaxial tensile tests at 80 °C under conditions at which large plastic strains are obtained. The intrinsic stress-strain behavior of the material and the strain induced volume changes were simultaneously determined by means of a novel video-controlled system. It was observed that PMMA experiences a complex volume variation involving compaction and dilatation stages. These effects are correlated with orientation and crazing mechanisms.
Enhanced Toughness Properties in Nanostructured Glassy Polymers by all-Acrylic Block Copolymers Prepared by Controlled Radical Polymerization
Pierre Gérard, Olivier Guerret, May 2004
All-acrylic block copolymers comprising rigid and rubbery blocks tethered together are prepared by a recently developed Controlled Radical Polymerization process, mediated by the SG1 nitroxide.The self-assembly of block copolymers at a molecular scale produces transparent nanostructures that are thermodynamically robust and can be processed repeatedly while maintaining favorable properties. Besides ductility due to confinement, nanostructuration of all-acrylic block copolymers can trigger new types of deformation mechanisms under dynamic loading and improve the toughness properties.
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