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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
ANALYSIS AND FABRICATION OF FOAM DIELECTRIC ANTENNA SPACERS
Jonathan S. Colton , Christopher Blandin, May 2010
Dielectric materials are used as spacers in antennas. The design of the dielectric determines the properties of the antenna. The insertion of high dielectric materials in a specific pattern into a low dielectric matrix material is one means to accomplish this. This paper reports on the insertion of metal cylinders (wire or nails) into polymer foams to produce such a material. Depending upon the antenna properties desired the patterns and number of nails vary tremendously. Varying the depths of the nails into the antenna spacers is also important. A penetration model was developed that calculates the forces required to penetrate a nail into foam. Experimental observations are used to verify the model. These equations allow one to predict the forces required for a nail to be inserted into foam to a desired depth thereby facilitating manufacture of these dielectric materials.
ANALYSIS AND FABRICATION OF FOAM DIELECTRIC ANTENNA SPACERS
Jonathan S. Colton , Christopher Blandin, May 2010
Dielectric materials are used as spacers in antennas. The design of the dielectric determines the properties of the antenna. The insertion of high dielectric materials in a specific pattern into a low dielectric matrix material is one means to accomplish this. This paper reports on the insertion of metal cylinders (wire or nails) into polymer foams to produce such a material. Depending upon the antenna properties desired, the patterns and number of nails vary tremendously. Varying the depths of the nails into the antenna spacers is also important. A penetration model was developed that calculates the forces required to penetrate a nail into foam. Experimental observations are used to verify the model. These equations allow one to predict the forces required for a nail to be inserted into foam to a desired depth, thereby facilitating manufacture of these dielectric materials.
A PHENOMENOLOGICAL CONSTITUTIVE MODEL FOR STRAIN SOFTENING PREDICTION IN SEMI-CRYSTALLINE POLYMERS
Mariajosé Pineda Manzano , Joel Bohórquez , Agustín Torres, May 2010
Strain softening in semi-crystalline polymers is one of their most important viscoelastic characteristics. Compared with other materials polymers are very sensitive to temperature and strain rate and there are many elements like molecular structure density amorphous fraction that can affect their mechanical behavior. A new phenomenological model with strain strain rate and temperature dependence on stress was developed based on the G’sell & Jonas model with the addition of a new expression used to predict the strain softening phenomena completing the whole mechanical behavior of semi-crystalline polymers from initial strain till fracture. Three experimental curves of each material converted to their true tensile stress-strain curves that includes variation in strain rate and temperature are needed to estimate the seven material coefficients of the model. Model verification was performed on various materials such as PE PP PET and PA (Nylon). This model was developed to further study the complex deformation patterns that occur in ductile thermoplastic materials subjected to impact loads.
A PHENOMENOLOGICAL CONSTITUTIVE MODEL FOR STRAIN SOFTENING PREDICTION IN SEMI-CRYSTALLINE POLYMERS
Mariajosé Pineda Manzano , Joel Bohórquez , Agustín Torres, May 2010
Strain softening in semi-crystalline polymers, is one of their most important viscoelastic characteristics. Compared with other materials, polymers are very sensitive to temperature and strain rate, and there are many elements, like molecular structure, density, amorphous fraction, that can affect their mechanical behavior. A new phenomenological model with strain, strain rate and temperature dependence on stress was developed based on the G'sell & Jonas model with the addition of a new expression used to predict the strain softening phenomena, completing the whole mechanical behavior of semi-crystalline polymers from initial strain till fracture. Three experimental curves of each material, converted to their true tensile stress-strain curves, that includes variation in strain rate and temperature, are needed to estimate the seven material coefficients of the model. Model verification was performed on various materials such as PE, PP, PET and PA (Nylon). This model was developed to further study the complex deformation patterns that occur in ductile thermoplastic materials subjected to impact loads.
A GPC-Mx Approach Of Improving Rheology-Mwd Prediction For Polypropylene
Wallace W. Yau , Jian Wang , Rongjuan Cong , David Gillespie , Joe Huang, May 2010
A new GPC polydispersity parameter, MxR, was introduced in this study. The MxR value, based on the GPC-Mx concept originally proposed by Yau [1], was found to be more suitable to account for the effect of different parts of the polymer molecular weight distribution (MWD) on rheology measurements at different shear rates than do the traditional polydispersity index based on the ratio of Mz, Mw and Mn values. By using this Mx-approach on a set of polypropylene homopolymers, we show that a much improved correlation indeed exists and can be achieved between GPC measurement with the rheology polydispersity indices of PDI and ModSep. Also presented in the paper is the improved correlation between melt flow rate (MFR) and molecular weight (MW) by using this Mx approach.
AN EXPERIMENTAL INVESTIGATION INTO MELT PUMP PERFORMANCE
Walter S. Smith , Luke A. Miller , Timothy W. Womer, May 2010
Melt pump performance and efficiencies will vary according to the viscosity of the resin being pumped, and the discharge pressure that the melt pump will need to overcome. Resin melt temperature differences and power requirements of the pump, will vary according to the resin, and conditions that the pump will operate under. This paper will explore the processing differences in (3) resins on gear pump performance at (4) different pump speeds, at three different discharge pressures. Discharge pressures on the pump will be varied keeping the suction pressure constant, thus increasing the change in pressure across the pump. Melt temperature, and pump efficiency. melt pump motor amperage, and total output, (kg/hr) will then be measured and recorded.
EFFECT OF ALUMINA NANOPARTICLES ON THE PROPERTIES OF LOW-VISCOSITY CYANATE ESTER ADHESIVES FOR COMPOSITE REPAIR
Wilber Lio , Katherine Lawler , Xia Sheng , Mufit Akinc , Michael R. Kessler, May 2010
Polymer matrix composites (PMCs) are susceptible to microcracks and delaminations from impacts and thermal/mechanical loadings that greatly reduce their mechanical integrity. This is especially a problem for high-temperature PMCs because current repair resins have low glass transition temperatures (Tg's) that stem from the low prepolymer viscosities required of injectable resins. Bisphenol E cyanate ester has both a high cured Tg and low prepolymer viscosity, ideal for the injection repair of high-temperature PMCs. Alumina nanoparticles were incorporated to improve adhesive strength and engineer prepolymer viscosity. Lap shear tests were performed to evaluate the effects of alumina nanoparticles on the adhesive strength of the resin.
TRANSIENT RHEOLOGY OF A POLYPROPYLENE MELT REINFORCED WITH LONG GLASS FIBERS
Hesam Ghasemi , Pierre J. Carreau, Musa R. Kamal, May 2010
The purpose of this research is to understand fiber orientation of long glass fibers (> 1mm) in polymer melts and the associated rheology in well-defined simple shear flow. Specifically, we are interested in associating the rheological behavior of glass fiber reinforced polypropylene with the transient evolution of fiber orientation in simple shear in an effort to ultimately model fiber orientation in complex flow. A sliding plate rheometer was designed to measure stress growth in the startup and cessation of steady shear flow. Results were confirmed by independent measurements on another sliding plate rheometer13. A fiber orientation model that accounts for the flexibility of long fibers, as opposed to rigid rod models commonly used for short fibers, was investigated and results are compared with experimentally measured values of orientation. The accuracy of this model, when used with the stress tensor predictions of Lipscomb, is evaluated by comparing against experimental stress growth data. Samples were prepared with random initial orientation and were sheared at different rates. Results show that fiber flexibility has the effect of retarding transient fiber orientation evolution. Additionally, it is shown that the stress growth measurements provide results that are not fully explained by the chosen models.
CHALLENGING THE PARADIGM OF MICROCELLULAR FOAMS: MECHANICAL PROPERTIES OF LOW-DENSITY CYCLO-OLEFIN COPOLYMER FOAMS
Richard Gendron , Martin Bureau, May 2010
Low-density foams of ethylene-norbornene copolymers were produced and their mechanical properties in compression investigated. Microcellular morphologies were observed with mean cell diameters lower than 20 ?m. Although the cyclo-olefin copolymer (COC) resin shares similar mechanical properties with polystyrene elastic modulus and compressive strength of the microcellular COC foams were much lower than the values for standard PS foam having larger cells (100-200 ?mrange) comparison made at the same density i.e. in the 50- 100 kg/m3 range. This goes against the usually accepted paradigm of enhanced properties with microcellular foams. Mechanisms for such unexpected behavior are proposed.
CHALLENGING THE PARADIGM OF MICROCELLULAR FOAMS: MECHANICAL PROPERTIES OF LOW-DENSITY CYCLO-OLEFIN COPOLYMER FOAMS
Richard Gendron , Martin Bureau, May 2010
Low-density foams of ethylene-norbornene copolymers were produced and their mechanical properties in compression investigated. Microcellular morphologies were observed, with mean cell diameters lower than 20 ?¬m. Although the cyclo-olefin copolymer (COC) resin shares similar mechanical properties with polystyrene, elastic modulus and compressive strength of the microcellular COC foams were much lower than the values for standard PS foam having larger cells (100-200 ?¬m range), comparison made at the same density, i.e. in the 50- 100 kg/m3 range. This goes against the usually accepted paradigm of enhanced properties with microcellular foams. Mechanisms for such unexpected behavior are proposed.
MICROMOLDING FOR QUARTZ GLASS/POLYMER COMPOSITES
Darin VanDerwalker, Stephen Johnston, Dan Hazen, David Kazmer, May 2010
Micromolding with microscale surface features and thin-wall plates of the quartz glass/polymers composites were performed to fabricate a new micro-fluidic plate with glass. Effects of process parameters on processability and surface replication of the molded parts were evaluated. The replication ratio and internal morphology of molded green and sintered microparts were analyzed using SEM and a confocal laser scanning microscope. During sintering processes, the green molded composites shrank with removal of binder polymer. The internal morphology affected shrinkage of green molded composites. The surface replication ratio of molded and sintered parts showed high values. Sintered molded parts were produced with a high aspect ratio of 3.4 and 10 ?¬m micro-line width.
EFFICACY OF SATURATED DESIGN OF EXPERIMENTS IN MULTIVARIATE PROCESS CHARACTERIZATION
Darin VanDerwalker , Stephen Johnston , Dan Hazen , David Kazmer, May 2010
Process characterization provides a model of process responses as a function of process factors, which is useful for process optimization and quality control. In this paper, four Design of Experiments (DOE) are implemented for a thin wall molding process, including two fractional factorial designs, a D-optimal design, and a supersaturated fractional factorial design. The capability of the DOEs are subsequently analyzed with respect to the estimated main effects and defect prediction capabilities. The results indicate that fully saturated designs are satisfactory for process characterization, but all critical process factors should be investigated. Experimental designs having confounded process factors were found preferable to experimental designs of similar size that were not confounded, but investigated fewer factors.
REPLICATION PROPERTIES AND STRUCTURE IN MICROMOLDING WITH HEAT INSULATOR MOLD
Alan D. Jaenecke, May 2010
Micromolding with microscale surface features and thin-wall plates was performed to fabricate zirconia with heat-insulated molds. Effects of process parameters on processability and surface replication of the molded optical parts such as a diffraction grating and anti-reflective plates were evaluated. The replication ratio and higher-order structure of molded parts were analyzed using SEM and a polarizing optical microscope. Using an insulated mold, the flow length and surface replication ratio of molded parts increased. The molecular orientation of molded parts decreased using this mold, as it did in molding conditions of higher mold temperatures and injection temperatures.
ABRASION TESTING OF PACKAGING FILMS
Alan D. Jaenecke, May 2010
When packaging sterilized medical devices or products, the integrity of the film is essential to ensure sterility of the device until usage. With competitive forces prompting the use of thinner gauge films, the risk of abrasion-induced failures increases dramatically. Until recently, there have been no effective means for packaging engineers to quantify which films would be most suitable for final applications. The Flexible Material Abrasion Kit allows engineers to perform a controlled laboratory test and analyze the variables that may influence the abrasion resistance of packaging films. This paper presents the concept behind the device and describes an actual case study.
MULTIVARIATE ROBUSTNESS MEASUREMENT
David Kazmer , Stephen Johnston , Darin VanDerwalker, May 2010
Multivariate modeling methods such as Principle Components Analysis are increasingly being used for quality control. The capability of such PCA models are traditionally verified by changing the process settings on an individual basis until a process fault is encountered. While such an approach is valid it is inefficient and does not consider interactions between multiple process settings. In this paper a design of experiments (DOE) is applied to more effectively identify process constraints with greater precision than the traditional fault identification approach. The method is demonstrated with the production of short shots and indicates significant differences between univariate and multivariate analyses with respect to yield predictions.
MULTIVARIATE ROBUSTNESS MEASUREMENT
David Kazmer , Stephen Johnston , Darin VanDerwalker, May 2010
Multivariate modeling methods such as Principle Components Analysis are increasingly being used for quality control. The capability of such PCA models are traditionally verified by changing the process settings on an individual basis until a process fault is encountered. While such an approach is valid, it is inefficient and does not consider interactions between multiple process settings. In this paper, a design of experiments (DOE) is applied to more effectively identify process constraints with greater precision than the traditional fault identification approach. The method is demonstrated with the production of short shots, and indicates significant differences between univariate and multivariate analyses with respect to yield predictions.
IN-SITU REINFORCED THERMOSET COMPOSITES USING CRYSTALLIZABLE SOLVENTS
O. Sinan Yordem , Alan J. Lesser, May 2010
This study demonstrates an approach to generate reinforcement in thermosetting polymers through crystal growth of low molecular weight crystallizable solvents. Phase separation and crystallization in blends of dimethylsulfone (DMS) and diglycidyl ether of bisphenol- A monomer were investigated via small angle laser scattering and optical microscopy at different isothermal conditions along with crosslinked mixtures using 1 3- Phenylenediamine. Reaction conditions which lead to suitable reinforcements were identified. It is also shown that DMS crystals grow anisotropically to form faceted geometries that resemble chopped-fiber-like morphologies as well as show unique ways of anchoring to the matrix.
IN-SITU REINFORCED THERMOSET COMPOSITES USING CRYSTALLIZABLE SOLVENTS
O. Sinan Yordem , Alan J. Lesser, May 2010
This study demonstrates an approach to generate reinforcement in thermosetting polymers through crystal growth of low molecular weight crystallizable solvents. Phase separation and crystallization in blends of dimethylsulfone (DMS) and diglycidyl ether of bisphenol- A monomer were investigated via small angle laser scattering and optical microscopy at different isothermal conditions along with crosslinked mixtures using 1,3- Phenylenediamine. Reaction conditions which lead to suitable reinforcements were identified. It is also shown that DMS crystals grow anisotropically to form faceted geometries that resemble chopped-fiber-like morphologies as well as show unique ways of anchoring to the matrix.
THE USE OF RHEOLOGICAL AND THERMAL FRACTIONATION METHODS FOR THE ASSESSMENT OF NUCLEATING AGENT EFFICIENCY IN POLYPROPYLENE
Eric Moskala, May 2010
The increasing diversity of commercial polypropylene products in recent years, related to the increase in the production volumes of PP, has led to a high number of studies dealing with structure-specific nucleating agents (NAƒ??s). Experiments on sorbitol-based NAƒ??s suggest that the nucleation function of this group of nucleating agents is a result of hydrogen bonding and self-assembly. So far, nucleation studies have been conducted in an indiscriminate manner with little reference to the exact effect of PP structure on nucleating behaviour of NAƒ??s. However, given the variety of commercial PP structures produced today, the question on the existence of synergy between polypropylene structure and nucleating efficiency of NAƒ??s remains open. The SIST (Stepwise Isothermal Segregation Technique) has been used in this study as a fast and efficient method to characterize a group of random PPƒ??s having different structures, giving the lamellar thickness distribution. In addition, temperature sweep measurements were performed to study the effect of flow on the interaction between NA and PP. In this way, small discrepancies between different materials can be pointed out to assess the nucleating efficiency of the nucleating agent.
AN APPROACH TO POLY(1,2-DICHLOROETHYLENE) SYNTHESIS VIA RING-OPENING METATHESIS POLYMERIZATION (ROMP)
Xianlong Ge , William H. Starnes Jr., May 2010
The preparation of poly(1,2-dichloroethylene), an unknown material that is expected to be a superb engineering thermoplastic, was explored. The ROMP of cis-3,4-dichlorocyclobutene quantitatively yielded a white linear polymer with 'CHClCHClCH=CH' repeating units. However, its subsequent addition chlorination could not be made to occur to a detectable level. Steric hindrance and/or electronic deactivation due to the inductive effect of Cl apparently made the chlorination impossible. Furthermore, thermal degradation of a series of model compounds indicated that polymers containing (CHCl)n (n ' 3) structures would have low thermal stabilities.


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