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
Melt Blending Graphite into Poly(Ethylene-2,6-Naphthalate)
Hyunwoo Kim, Christopher Macosko, May 2007
Graphite can be an attractive reinforcement for polymers due to its high stiffness and low thermal expansion as well as high electric conductivity. Graphite was melt blended into poly(ethylene-2,6-naphthalate) (PEN). After molding extruded composites into films via biaxial squeezing and uniaxial stretching, their stiffness, thermal expansion and gas barrier properties were tested. Even though graphite in PEN matrix appeared to form unintercalated or partially intercalated morphology, noticeable enhancements in composite stiffness and hydrogen barrier properties were observed. Less improvement in dimensional stability was found. We evaluated average aspect ratios of anisotropic graphite sheets embedded in PEN by interpreting experimental data with composite theories. Young's modulus and dimensional stability of composites were dramatically improved by film drawing.
Impact of Approximating the Initial Bubble Pressure on Cell Nucleation in Polymeric Foaming Processes
Siu N. Leung, Hongbo Li, Chul B. Park, May 2007
According to the classical nucleation theory, the free energy barrier for bubble nucleation and thereby the nucleation rate are functions of the bubble pressure, Pbubble. In computer simulations of polymeric foaming processes, almost all previous research has approximated the value of Pbubble by the saturation pressure, Psat. In this paper, the thermodynamic equilibrium condition and the Sanchez- Lacombe (SL) equations of state (EOS) are employed to determine the value of Pbubble. It is shown that the Pbubble approximation using Psat will lead to significant overestimations of the nucleation rate and the final cell density.
Influence of Surface Energy on Dispersion and Flexural Properties of PS/Phosphonium Organoclay Nanocomposites
Jorge Uribe Calderon, Musa R. Kamal, May 2007
Phosphonium-modified montmorillonite (PMM) organoclays were used to produce polystyrene (PS)/clay nanocomposites by melt processing. Two PS resins with different molecular weights were used, along with four different PMM organoclays. The structure of the resulting nanocomposites was characterized using wide angle X-ray and transmission electron microscopy. It was found that the quality of clay dispersion, nanocomposite thermal stability, and flexural mechanical properties depend on the combination of organoclay type and PS molecular weight. The differences are discussed in light of the interfacial tension values measured for the different PS/PMM systems.
Fast Acquisition Melt Pressure Measurements to Detect Flow Instabilities. A New Option for Capillary Rheometers
A. Göttfert, J. Sunder, May 2007
Flow instabilities cause various problems in extrusion blow- or flat film processes. Especially shark skin is affected by the molecular structure. This phenomenon is analyzed in various scientific works using apparatus that are complex or difficult in operation.A new set-up, now available is being presented as an option for new and existing capillary rheometers, consisting of a special designed die and a fast responsive transducers system. The software allows the evaluation of diverse pressure frequency regimes causing flow instabilities. Measurement examples are given for different shear rates and polymers. The measured frequency regimes are related to molecular parameters.
Casting of Zein Protein Polymers
Gowrishankar Srinivasan, Michael Kessler, David Grewell, May 2007
This paper reviews an investigation of the processability and properties of commercially available corn protein polymers for cast film products. Different formulations of protein substrates were cast and characterized for their mechanical properties. In this study it was seen that zein plastic sheets could be cast with tensile strengths as high as 6 MPa with a strain to failure of 6%. In addition, ultrasonic treatment of the solution, prior to casting, reduced the tensile strengths; however, the treatment did enhance the strain to failure to as high as 200%. Lastly, the addition of nanoclays also reduced the tensile strength of the cast films.
Preparation of Gold Nanoparticles Filled Poly Dimethyl Siloxane Membrane for Gas Separations and its Reverse Selective Phenomena
R.Vedaiyan, C.Banerjee, Jag Sankar, J.Lou, May 2007
A novel nanocomposite membrane, poly dimethyl siloxane (PDMS)/Au was prepared for carbon dioxide/methane separation. Synthesis of stabilized nano particles is also reported. The nanoparticles were characterized by UV-visible spectroscopy and transmission electron microscopy (TEM). The hybrid membrane was characterized morphologically by scanning electron microscope (SEM) and the change in inter-segmental distance due to filler loading by wide angle X-ray diffraction patterns (WAXD). The gas transport properties were measured at different pressures and temperatures. The effects of filler loading on permselectivity, diffusivity selectivity and solubility selectivity are reported for CO2/CH4 separation. Reverse selective phenomena of PDMS/Au nanocomposite membrane over the conventional PDMS membrane is explained based on sorption kinetics of CO2.
Viscoelastic Flow in Micro-Injection Molding
Xin Hu, Chuntai Liu, Guojun Xu, L. James Lee, May 2007
Understanding the free surface flow of viscoelastic fluids in micro-channels is important for the design and optimization of micro-injection molding processes. In this paper, flow visualization of a non-Newtonian polyacrylamide (PA) aqueous solution in a transparent polymethylmethacrylate (PMMA) channel with microfeatures was carried out to study the flow dynamics in micro-injection molding. The transient flow near the flow front and vortex formation in microfeatures were observed. Simulations based on the control volume finite element method (CVFEM) and the volume of fluid (VOF) technique were carried out to investigate the velocity field, pressure, and shear stress distributions. The mesoscopic CONNFFESSIT (Calculation of Non-Newtonian Flow: Finite Elements and Stochastic Simulation Technique) method was also used to calculate the normal stress difference, the orientation of the polymer molecules and the vortex formation at steady state.
Novel PET Nanocomposites with Enhanced Barrier Performance of Interest in Food Packaging Applications
M.D. Sanchez-Garcia, E. Gimenez, J.M. Lagaron, May 2007
PET is one of the polymers most widely used in the packaging industry. However, it is highly desirable to enhance its barrier properties for applications such as carbonated drinks and for other rigid and flexible packaging applications. The nanocomposites route offers unique possibilities to enhance the properties of this material, provided that adequate thermally resistant and legislation complying nanofillers are used. This paper presents novel nanocomposites of PET with enhanced barrier properties to oxygen, water and d-limonene based on a new specifically developed food contact complying montmorillonite grade. Morphology and thermal properties are also discussed as a function of filler content.
An Examination of the Relative Impact of Common Potable Water Disinfectants (Chlorine, Chloramines and Chlorine Dioxide) on Plastic Piping System Components
Sarah Chung, Ken Oliphant, Patrick Vibien, Jingguo Zhang, May 2007
The three most common disinfectants in potable water are chlorine, chloramines and chlorine dioxide. While these disinfectants are all oxidants, their unique characteristics can result in a significantly different impact on the performance of plumbing system components. In this paper, the chemistry and characteristics of the oxidants are discussed in the context of oxidative degradation of plastic piping system components. Testing strategies to ensure material performance in potable water applicationsare presented and reviewed.
Evaluation of Alternative Injection Locations with Variability Consideration in an Automotive Part
Thania Gaído, Narayan Bhagavatula, José M. Castro, May 2007
Selecting proper process settings is crucial in injection molding as part quality is greatly influenced by the process conditions. The locations of the injection gate need to be decided before the mold is made. Other processing variables can be adjusted during start up; however changing the gate location at a later stage involves great cost. In this work, we analyze the effect of gate location on process consistency for an automotive part, using a multivariable optimization method called Data Envelopment Analysis (DEA).
Effect of E-Beam Sterilization on the Physical and Optical Properties of Medical Plastics
Gary M. Stack, Ken Breeding, May 2007
Electron beam (E-beam) exposure is becoming increasingly popular as a lower cost alternative for the sterilization of medical devices and rigid medical packaging. The objective of this study was to determine the effect of E-beam sterilization on several plastics typically used in medical devices and packaging including: copolyesters, polycarbonate, acrylic and cellulosic polymers. Exposures of 25 and 50 kGy (2.5 to 5.0 Mrad) were found to induce significant yellowing. However, color measurements performed at various intervals subsequent to the exposures indicated that the yellowing decreased over time, each plastic to a different degree. Effects of these E-beam exposures on physical properties of these plastics were also determined.
Process Optimization of Injection Molding by Integrating Numerical Simulation with Surrogate Modeling Approaches
Jian Zhou, Lih-Sheng Turng, May 2007
An integrated optimization system that can adaptively and intelligently determine the optimal process conditions for injection molding has been developed. Nonlinear statistical regression techniques and design of computer experiments are used to establish adaptive surrogate models that can substitute time-consuming numerical simulation and quickly provide predictions with adequate accuracy for system-level optimization. While the Gaussian process (GP) surrogate model is being refined, a multi-objective genetic algorithm (GA) is employed for the global optimal solutions in a concurrent fashion. The performance and capability of various surrogate modeling approaches—i.e., Gaussian process (GP), artificial neural network (ANN), and support vector regression (SVR)—are also investigated and compared in terms of accuracy, robustness, and efficiency. The examples presented in this paper show that the adaptive optimization procedure helps engineers determine optimal process conditions more efficiently and effectively.
An Examination of Field Failures of Plastic Piping System Components in Potable Water Applications
Sarah Chung, Tony Kosari, Tieqi Li, Ken Oliphant, Patrick Vibien, Jingguo Zhang, May 2007
Disinfectants in potable water, such as chlorine and chlorine dioxide, can impact the performance of plastic piping system components. In this paper, field failures of plastic piping components exposed to potable water are examined. Analysis of the oxidative and mechanical initiation and propagation mechanisms leading to failure is performed. Field and laboratory samples are also compared to assess the test methodologies that are available to evaluate the impact of disinfectants on plastic piping systems.
Mathematical Model and Numerical Analysis of Polymer Melt Flow and Heat Transfer in a Cooling Extruder
Lilac Cuiling Wang, Markus Bussmann, Chul B. Park, May 2007
This paper presents a mathematical model and numerical analysis of momentum transport and heat transfer of polymer melt flow in a standard cooling extruder. The finite element method is used to solve the three-dimensional Navier–Stokes equations based on a moving barrel formulation; a semi-Lagrangian approach based on an operator-splitting technique is used to solve the heat transfer advection–diffusion equation. A periodic boundary condition is applied to model fully developed flow. The effects of polymer properties on melt flow behavior, and the additional effects of considering heat transfer, are presented.
Compressed Viscose Sponges as Actuators
Jan Spoormaker, Anton Heidweiller, May 2007
Compressed viscose sponges can be applied in devices in which a force is exerted when the compressed sponge is wetted. These sponges are used as actuator in a device to rescue keys attached to the floating device when it drops in water.Experiments have been carried out to determine the magnitude of the exerted force as a function of the mass of compressed sponges, but also as a function of the gap between the sponge and the object on which the force is exerted.From the experiments it was learned that the gap is predominant. Compressed sponges exert a force which is more than 4 times higher than the case when a gap of more than 1.5 mm exists.
Effects of Surface Geometry of Nucleating Agents on Heterogeneous Nucleation
Siu N. Leung, Chul B. Park, Anson Wong, May 2007
Ideal nucleating agents are expected to improve the cell morphology of plastics foams (i.e., higher cell densities, smaller cell size, and narrower cell size distribution) by providing heterogeneous nucleation sites. Surface geometry is one of the factors that govern the nucleating power of nucleating agents. Based on the computer simulation of a batch foaming process of polystyrene/carbon dioxide system, this paper indicates that nucleating agents having numerous crevices of small semi-conical angles, are most desirable for polymeric foaming processes.
Application of Polymer Welding Theory to Industrial Process Design
Ronald D. Moffitt, Wei Zhang, William J. Donohue, Tom A. Zbell, W. Charles Mattox, Wesley J. Queen, May 2007
Welding time shifting expressions based upon time-temperature superposition (tTS) and hot air nozzle spacing were used to establish industrial process scale-up and design relationships for a continuous cured-in-place pipe (CIPP) liner manufacturing process. The application of tTS was successfully demonstrated to apply equally well to the commercial CIPP assembly bonding of thermoplastic polyurethane tape to a coated thermoplastic polyurethane coated felt substrate and to the hot air self-welding of a polyester needle-punched felt.
Characterization of Model Urethanes and Ureas Based on Hydrogenated Methylenediphenldiisocyanate via Solution and Solid State NMR Spectroscopy
Daniel P. Dempsey, May 2007
Models for hard-block segmented polyurethanes were synthesized using a pre-polymer process. Urethane linkages were synthesized using hydrogenated methylenediphenyldiisocyanate (H12MDI) reacted with dimethylol propionic acid (DMPA) and hexanol. Urea linkages were synthesized using H12MDI and hexylamine. The resulting small molecules were then subjected to solution and solid state nuclear magnetic resonance (NMR) spectroscopy to determine the reaction coordinates, to investigate possible side reactions, and to document 13C peaks and reaction times.
PVC Nanocomposites – Methods of Promoting Filler Dispersion
Marianne Gilbert, Noreen L Thomas, Xiaoran Zheng, Styliani Georgiadou, Brian Brooks, May 2007
The most widely used nanofillers for plastics are the organically modified nanoclays, in particular montmorillonite. However these clays cannot be used successfully in PVC, as they contain ammonium groups which accelerate PVC degradation. This paper considers a number of alternative nanofillers for both rigid and flexible PVC, and focuses on methods of dispersion of these fillers (involving mixing, melt blending, and polymerisation), suitable formulations to avoid thermal degradation, and potential for property enhancement.
Failure Analysis of Polypropylene Used in a Hot Water Environment – Effect of Different Stabilizer Systems
Dale B. Edwards, Lawrence J. Broutman, Alan I. Kasner, May 2007
Polypropylene has been used for many years in hot water applications with varying degrees of success. Failures in one instance were traced to a stabilizer package that inadequately protected the polymer in a hot, chlorinated water environment. This same stabilizer system performed extremely well in oven aging tests. The current study involved examination and analysis of failed samples from the field, along with laboratory aging studies designed to replicate the field failures and compare the performance of the stabilizer system in different environments.
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