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
MEASUREMENTS OF BIAXIAL STRESSES DURING THE COMPRESSION OF BULK RESIN FEED
Aaron P. R. Eberle, Gregorio M. Velez, Donald G. Baird, Peter Wapperom, May 2010
Compression of the bulk solids feed resin is important in solids conveying in single screw extruders. The compressive stresses in the solid bed act with friction to produce solids conveying flow. Classically, the stresses have been assumed isotropic. However, a laboratory test given here demonstrates the biaxial stress in solids feed. Measurements were made of the biaxial stresses during compression for HDPE, LDPE, LLDPE, PET pellets, and PET powder, and the results are correlated with some extruder solids conveying performance.
THE DYNAMIC BEHAVIOR OF A CONCENTRATED POLYMERIC SUSPENSION CONTAINING NON-BROWNIAN GLASS FIBERS IN SIMPLE SHEAR FLOW
Aaron P. R. Eberle , Gregorio M. Velez , Donald G. Baird , Peter Wapperom, May 2010
In this paper we study the dynamic behavior of a concentrated short glass fiber suspension subject to simple shear flow. In particular we are interested in determining the relationship between the stress growth functions (shear and first normal stress) and the evolution of the fibersƒ?? orientation distribution within the sample.Stress growth experiments in start up of flow are performed on a Rheometrics Mechanical Spectrometer (RMS-800). Samples at rest are deformed at a constant strain rate for a specified time (i.e. strain) that correlates various points of interest on a stress growth vs. strain plot.The sample temperature is then lowered below the suspension melt temperature ƒ??freezingƒ? the fiber orientation which is then characterized using confocal laser microscopy. The experimental results are compared to predictions based on the generalized Jeffery equation.It is found that the theory over predicts the rate at which the fiber orientation evolves.
THE EFFECTS OF COMONOMER DISTRIBUTION PROFILE ON THE BLOWN FILM PROPERTIES OF SINGLE SITE CATALYZED POLYETHYLENES
XiaoChuan (Alan) Wang, May 2010
To understand better the effects of comonomer distribution profiles on blown film properties, single site catalyzed (SSC) bi-component (narrow MWD homopolymer blended with narrow MWD copolymer) octene polyethylenes were prepared to exhibit both narrow MWD and highly reverse comonomer distribution profiles (final density of 0.917 to 0.930 g/cm3). Their blown film properties were compared with those from PE resins having conventional comonomer distribution profiles including hexene mPE and SSC octene PE. Blown film structure-property relationships are presented, and the excellent toughness results are generally explainable with the tie chain concept. However, exceptions exist for some MD tear strength data.
THERMAL OXIDATIVE STABILITY TESTS A RE-EXAMINATION
Lecon Woo , Vadim Krongauz , Bruce Eu, May 2010
DSC and TGA are two of the most widely used methods for studying thermal oxidative stability of polymers. Previous studies have shown that comparable Oxidative Induction Times ( OIT) can be obtained by either method. However since the two methods measure totally different sample properties during the oxidation process we conducted a more detailed study beyond the OIT quantity. Polymers which undergo chain scission and crosslinking are compared with both techniques. A further elaboration of a more general kinetics model was also attempted. Result of these evaluations toward assessing the oxidative stability and possible shelf life prediction will be presented
CONJUGATED POLYMER PHOTOVOLTAIC SOLAR CELLS ' MANUFACTURING, TROUBLESHOOTING AND MORPHOLOGY
Sean Petzold , Abdullah Khazaal , Chuan Wang , Grant James , Irfan Ahmed , Tim Osswald, May 2010
Deposition of nanoscale films was used to manufacture organic photovoltaic solar cells. The cells use conjugated polymers as donors and fullerenes as acceptors, which were spin-coated onto a PET-ITO substrate and finished with a sputtered aluminum layer. In order to achieve an actual working cell the measurement of the thickness of nanoscale thin films must be understood completely. The thickness of the coating layers were measured using Atomic Force Microscopy (AFM), UV spectroscopy, an Ellipsometer, White Light Interferometer, Transmission Electron Microscope (TEM), and a high powered microscope with a micrometer with a nanoscale resolution. Cell morphology was studied using atomic force microscopy and UV spectroscopy. The effects of annealing, PEDOT:PSS and LiF insertion, electric fields, solution concentration, and use of carbon nanotubes will be explored in the future.
LOW CTE THERMOPLASTIC AND CROSSLINKED ELASTOMERS
M. Marquez, M. Matos, M. L. Arna, F. López-Carrasquero, C. Rosales, A. J. Müller, May 2010
A new process method to prepare and characterize elastomers with lower coefficients of thermal expansions is studied. A styrene butadiene styrene (SBS) thermoplastic elastomer containing physical as well as chemical crosslinks is used to achieve a two-step cured double-network material. Prior to the second-step cure, uniaxial extension step is introduced. Results from conventional monotonic tensile tests, differential scanning calorimeter (DSC) and thermo-mechanical properties are presented. Based on the results it is observed that an interesting material is obtained showing switchable mechanical properties, slightly higher Tg and lower coefficient of thermal expansion.
PLASTICS INDUSTRY BUSINESS STRATEGIES DURING HARD TIMES
Byoung-Ho Choi, Rajen Patel, A. Willem deGroot, Mehmet Demirors, Lizhi Liu, Kenneth Anderson, May 2010
The major economic downturn of 2008-2010 has brought great changes in the US manufacturing sector. Not just most major banks, but two automobile manufacturers are now government-controlled with all of the accompanying political baggage and unpredictability. The plastics industry has seen a number of polymer producers shut down US plants with the intention of sourcing in the future from Persian Gulf plants. Is it time for processors to move offshore or is there still business here in the US? Actually, some processors are finding business at home ƒ?? a bit of which has moved back to the US from offshore ƒ?? as well as opportunities for export. Globalization creates business opportunities in the US as well as overseas, for managers canny enough to find them. The global economic shakeout seems to be at least partially levelling the playing field and this paper will review these opportunities.
INVESTIGATION ON THE TEAR PROPERTY OF POLYETHYLENE BLOWN FILMS AT VARIABLE ANGLES
Byoung-Ho Choi , Rajen Patel , A. Willem deGroot , Mehmet Demirors , Lizhi Liu , Kenneth Anderson, May 2010
Tear is a key physical property of polyethylene (PE) blown films. There are many variables which affect the overall tear property such as tear path, plastic deformation wake, and so on. In this study, five blown PE films were prepared and tested by the Elmendorf tear test at five sampling angles, i.e. 0 (MD), 30, 45, 60, 90 (CD) degrees.Tear values were analyzed statistically and the variation of the tear data was investigated based on the observation of the tear samples. The mechanism of severely curved crack, i.e. J-tear, was also studied to understand the tear property variation of blown PE films.
MANUFACTURING AND CHARACTERIZATION OF NANO-COMPOSITE LINEAR STRAIN SENSORS
Donald Baird, May 2010
This study explores the potential of using polymer nanocomposites for a strain sensor application. This work focuses on the development of such strain sensors made by casting vapor-grown carbon fiber (VGCF) reinforced polydimethylsiloxane (PDMS). The tensile properties are determined as a function of the VGCF content. Furthermore, the percolation threshold is determined; and the electrical conductivity of nanocomposites with VGCF content above the percolation threshold is measured. Finally, the relationship between electrical conductivity and mechanical strain is determined for loading/unloading cycles to verify the durability and repeatability of the sensors.
CORRELATION OF FILM CASTING BEHAVIOR WITH NON-LINEAR RHEOLOGY FOR A SERIES OF HDPE’S WITH DIFFERENT DEGREES OF SPARSE LONG CHAIN BRANCHING
Donald G. Baird, May 2010
The degree of film-width reduction or necking during film-casting is analyzed for several metallocene-catalyzed high density polyethylenes HDPE with varying degrees of sparse long-chain branching LCB. It is found that the addition of sparse LCB reduces the degree of necking to a greater degree than broadening the MWD. Analysis of the uniaxial extensional and dynamic shear rheology with the pom-pom constitutive model reveals that a distribution of branches along shorter relaxation time modes is important in reducing necking at higher drawdown ratios.
CORRELATION OF FILM CASTING BEHAVIOR WITH NON-LINEAR RHEOLOGY FOR A SERIES OF HDPE'S WITH DIFFERENT DEGREES OF SPARSE LONG CHAIN BRANCHING
Donald G. Baird, May 2010
The degree of film-width reduction or necking during film-casting is analyzed for several metallocene-catalyzed high density polyethylenes, HDPE, with varying degrees of sparse long-chain branching, LCB. It is found that the addition of sparse LCB reduces the degree of necking to a greater degree than broadening the MWD. Analysis of the uniaxial extensional and dynamic shear rheology with the pom-pom constitutive model reveals that a distribution of branches along shorter relaxation time modes is important in reducing necking at higher drawdown ratios.
MODELING INTERFACIAL STRENGTH OF POLYBUTYLENE SUCCINATE(PBS)/POLYPROPYLENE(PP) MULTILAYER INJECTION-MOLDED PART USING FINITE ELEMENT METHODS
Siu N. Leung, Anson Wong, Chul B. Park, May 2010
Polypropylene (PP)-based sandwich injection moldings containing biodegradable polymers in the core were carried out. Interfacial adhesion between the skin and the core is essential for obtaining sufficient mechanical strength for commercial applications. In order to investigate the interfacial strength between the skin and the core, the ASTM/ISO scratch test was used and critical delamination load for delamination was determined. For comparison, an 180o peel test was also conducted, whereby the skin was peeled off from the core, to measure its adhesive force in a different way. Numerical simulation using FEM was applied to these experiments to study interfacial strength. Destruction of the interfacial layer was defined by either a critical stress or critical strain criterion. The critical strain criterion appears to better describe the phenomenon in these two experiments. FEM simulation could qualitatively correlate with these behaviors, suggesting that delamination could be described as a strain dominant phenomenon.
A NEW INTERPRETATION TO THE TALC-ENHANCED POLYMERIC FOAMING PROCESS
Siu N. Leung , Anson Wong , Chul B. Park, May 2010
Cell nucleating agents are commonly used in polymeric foaming processes to enhance cell nucleation. It has been widely believed that the enhancement was through the promotion of heterogeneous nucleation. Even though it has been observed by other researchers that additional bubbles were nucleated near the growing cells despite the low gas concentration the mechanisms have not yet been clearly identified. It seems that with the presence of talc particles the shear and/or extensional fields generated by the growing cells that are near them have a stronger effect on bubble nucleation than the depleted gas concentration. Using the concept of the critical radius for bubble nucleation and the stress fields generated around the talc particles this paper presents a mechanism of cell nucleation for this case.
A NEW INTERPRETATION TO THE TALC-ENHANCED POLYMERIC FOAMING PROCESS
Siu N. Leung , Anson Wong , Chul B. Park, May 2010
Cell nucleating agents are commonly used in polymeric foaming processes to enhance cell nucleation.It has been widely believed that the enhancement was through the promotion of heterogeneous nucleation. Even though it has been observed by other researchers that additional bubbles were nucleated near the growing cells despite the low gas concentration, the mechanisms have not yet been clearly identified. It seems that, with the presence of talc particles, the shear and/or extensional fields generated by the growing cells that are near them have a stronger effect on bubble nucleation than the depleted gas concentration. Using the concept of the critical radius for bubble nucleation and the stress fields generated around the talc particles, this paper presents a mechanism of cell nucleation for this case
TRACKING PHASE SEPARATION KINETICS OF BLOCK COPOLYMER SOLUTIONS USING DYNAMIC MECHANICAL MEASUREMENTS
Vandita Pai-Paranjape, André Van Zyl, Jan Pleun Lens, Dake Shen, May 2010
Rheology is used to track the phase separation kinetics of block copolymer solutions during processing and then modeled using the Avrami equation. Previous studies dealt explicitly with disorder-order transitions following shallow temperature quenches. To make this work applicable to the processing of solution-cast films, styrenic block copolymers in solvents of varying selectivity are cast as thin, dilute samples and dried isothermally so that various constant-concentration kinetics can be tracked. Rheology proves to be useful in tracking both rapid and slow kinetics of diblock and triblock styrenic copolymers in toluene. It is found that the diblock copolymer undergoes faster ordering than a triblock copolymer of comparable molecular weight. A competition between thermodynamic driving forces and kinetic suppression of the phase separation exists as concentration changes. AFM images are provided to confirm the kinetic data and to understand the meaning of the Avrami exponent values determined for the different systems studied.
SCRATCH-RESISTANT TRANSPARENT POLYCARBONATES WITH ECO-COMPLIANT FLAME PROPERTIES
Vandita Pai-Paranjape , André Van Zyl , Dake Shen, May 2010
Polycarbonate resins possessing high surface hardness and improved scratch resistance have been developed for injection molding applications. Due to their transparent nature and good balance of physical and mechanical properties these resins find applications in the business equipment mobile phone and electronic device industries. They also possess increased resistance to oxygen and / or water vapor migration making them suitable candidates for medical packaging. New developments in the area of flame retardancy will be discussed in this paper.
SCRATCH-RESISTANT, TRANSPARENT POLYCARBONATES WITH ECO-COMPLIANT
Vandita Pai-Paranjape , André Van Zyl , Jan Pleun Lens , Dake Shen, May 2010
Polycarbonate resins possessing high surface hardness and improved scratch resistance have been developed for injection molding applications. Due to their transparent nature and good balance of physical and mechanical properties, these resins find applications in the business equipment, mobile phone and electronic device industries. They also possess increased resistance to oxygen and / or water vapor migration, making them suitable candidates for medical packaging. New developments in the area of flame retardancy will be discussed in this paper.
INFLUENCE OF THE INJECTION MOULDING PROCESSING PARAMETERS TO THE MECHANICAL PROPERTIES OF MICROCELLULAR FOAMED POLYCARBONATE
A.K. Bledzki , M. Rohleder , H. Kirschling, May 2010
Since many years microcellular foamed materials have been produced. The advantages are all well known but to improve the properties of the material it is necessary to understand the interrelationship between the morphology and the mechanical properties. Furthermore it is important to know how the processing parameters influence the morphology and the properties of the produced part. By understanding the relation between processing parameters and the consequential properties it becomes possible to create microcellular foamed parts with exactly defined properties. Equations by means of linear regression were created and the main influence processing parameters extracted. Out of this it is possible to define a processing window which leads to best mechanical properties for each specific load type.
INFLUENCE OF THE INJECTION MOULDING PROCESSING PARAMETERS TO THE MECHANICAL PROPERTIES OF MICROCELLULAR FOAMED POLYCARBONATE
A.K. Bledzki , M. Rohleder , H. Kirschling, May 2010
Since many years microcellular foamed materials have been produced. The advantages are all well known, but to improve the properties of the material it is necessary to understand the interrelationship between the morphology and the mechanical properties. Furthermore, it is important to know how the processing parameters influence the morphology and the properties of the produced part. By understanding the relation between processing parameters and the consequential properties, it becomes possible to create microcellular foamed parts with exactly defined properties. Equations by means of linear regression were created and the main influence processing parameters extracted. Out of this it is possible to define a processing window which leads to best mechanical properties for each specific load type.
APPLICATION OF TAGUCHI METHOD ON NYLON6 NANOCOMPOSITES THIN WALL IN MOLD DECORATION MOLDING
Kapil C. Sheth, Robert R. Gallucci, Gurulingamurthy Haralur, May 2010
Nylon6 and Nylon6 nanocomposites (addition of 2.0 wt% and 4.0 wt% Montmorillonite) were used as molding material for in mold decoration (IMD) molding (square plate specimen with thickness of 1.0mm). The Taguchi method with orthogonal arrays was used to determine important factors affecting ink washout in thin wall IMD molding. It was found that the significant contributing factors in the descending order were injection speed (29.30%), nanocomposites additives (21.62%) and film type (15.26%); moreover, higher melt temperature, higher mold temperature and lower injection would increase moldability for Nylon6 nanocomposites (4.0 wt%) combined with 0.125 mm thick PC film.
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