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
Swelling Interaction, Plasticization, and Antioxidant Extraction between Fiber Optic Cable Gels and Polyolefins
Brian G. Risch, May 1999
The effects of various waterblocking gels are investigated in relation to swelling behavior of polyolefins. Gel absorption is studied in polyethylene and polypropylene/ethylene copolymers as a function of temperature for a density range of 0.868g/cc to 0.948g/cc for polyethylene and 0.88 to 0.91g/cc for propylene/ethylene copolymers. The effect of swelling on antioxidant extraction is also studied as a function of antioxidant molecular weight and degree of swelling. Both factors show a strong influence on the amount of antioxidant extracted. A direct correlation is found between antioxidant extraction by gels and reduction in thermo-oxidative stability.
Comparison of Three Methods to Measure the Elongational Viscostiy of Polymer Melts: Entry Flow, Fiber Spinning and Uniaxial Elongation
Alexandros D. Gotsis, Qinfei Ke, May 1999
The melt viscosity of three commercial polyolefines (LDPE, LLDPE and HDPE) was measured in uniaxial elongational flow at constant extension rate, as well as by the Rheotens and the Entry Flow Methods. The melts showed the same MFI but differed in their extensional properties, reflecting the differences in their molecular structure. The indirect methods could also give meaningful estimates for the extensional viscosity of polymer melts, if the amount of accumulated extensional strain in each case was taken into consideration.
Compatibilization of PET/LLDPE Blends with MAH-g-LLDPE
L. Márquez, D.E. Gambus, M.P. Romero-Rato, M.A. Sabino, May 1999
Blends of Polyethylene terephtalate (PET) and Linear Low Density Polyethylene (LLDPE) compatibilized with maleic anhydride-grafted-LLDPE (MAH-g-LLDPE) were characterized. The addition of MAH-g-LLDPE produced a fine dispersed phase morphology and improved processability of blends. A decrease on the crystallization temperature and on the degree of crystallinity of the polyester and an increase on the elastic modulus and on the stress at break were observed. These effects could be attributed to the reduced interfacial tension as a result of the promoted interaction between the polymers by the functionalized polymer.
Linear Viscoelastic Properties of Polymeric Suspensions
Goknur Bayram, Ulku Yilmazer, Nese Orbey, May 1999
Linear viscoelastic properties of a model suspension containing hydroxyl terminated polybutadiene (HTPB) and glass beads with filler concentration up to 30% by volume were investigated by using a Haake parallel disk rheometer. For all the suspensions, it was observed that the rheological properties such as the storage modulus, G', loss modulus, G and complex viscosity ?* increases with the filler content ?. The relaxation spectra was calculated by using G' and G". The relaxation moduli Gi(?i?) decreased with the relaxation time ?i but increased with the filler content ?."
Compatibilization of PET/HDPE Blends
Tomas Lozano-Ramirez, Carlos Guerrero-Salazar, May 1999
Blends of Polyethylene terephthalate (PET) and High Density Polyethylene (HDPE) with and without compatibilizing agent have been studied. Both materials are widely used in the soft drink bottle industry. The compatibilizing agent was a copolymer of ethylene and methacrylic acid (surlyn). The olefinic segment of surlyn will be compatible with HDPE, while the acid groups will be affine with the similar groups from PET. The compatibility was investigated using different techniques such as differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy and X-ray spectroscopy.
Prediction of Service Life in a Chemically Active Environment Using Stress-Rupture Data
Anand R. Shah, Paul K. So, Lawrence J. Broutman, May 1999
The effect of chemical exposure on the stress rupture behavior of polyurethane, polyacetal and four acrylic materials was investigated. The polyurethane and polyacetal stress rupture data was used to provide the basis for verification of the expected service life of products made from these materials. The stress rupture data from four different acrylic materials was used to differentiate the materials on the basis of long term strength. The stress rupture data (applied stress vs. failure time) was obtained using a custom designed and built constant tensile load (CTL) testing apparatus.
Continuous Polymerization of Polyetheramide Tri-Block Copolymer in a Modular Intermeshing Counter-Rotating Twin Screw Extruder
Byung Hwa Lee, James L. White, May 1999
Polyetheramide tri-block copolymers have been polymerized in a modular counter-rotating twin screw extruder under a range of processing conditions, including temperature profiles and screw speeds. Polyetheramide tri-block copolymers had not been previously polymerized in a twin screw extruder. Thermal analysis and viscosity measurements clearly demonstrated that the formed copolymers have two separated domains arising from two different block segments. Studies were also made of melt spinning polyetheramide tri-block copolymer into oriented filaments. The formed filaments were characterized using birefringence. The melt spun fibers of polyetheramide tri-block copolymer showed higher elongation than those of polyamide 6 due to the existence of elastomers.
Novel BEM Simulation of Mixing in Polymer Flows Including Non-Linear Effects
Antoine C. Rios, Tim A. Osswald, May 1999
When numerically analyzing mixing in polymer processes, there are several difficulties that the engineer will encounter; such as moving boundaries, complex geometries and non-linear material behavior. The Boundary Element Method (BEM), as a technique which requires only boundaries (surfaces) to be meshed, is ideal to simulate problems with moving boundaries and complex geometries. However, the introduction of non-linear material behavior requires domain information. This study applies the Monte Carlo technique to integrate the domain and keep the boundary-only discretization. Results show the influence of non-linear effects, such as shear-thinning viscosity, when characterizing mixing in polymer processing equipment.
Orientation, Stress and Shrinkage Relationships for Amorphous and Semicrystalliane Polymers
A. Ajji, R.G. Matthews, R. Yan, N. Legros, K.C. Cole, May 1999
The dimensional stability, such as shrinkage strain or stress, of oriented films and sheets is an important factor in the application of these articles. High shrinkage may be desired for some applications or need to be minimized for others. Thus shrinkage control and monitoring is of paramount importance. On the other hand, it is well established for most polymer melts that the birefringence is simply related to the stress through the stress optical rule, and simple theories relate the stress and birefringence to the strain. In this paper, we investigate these relationships for oriented amorphous (polystyrene, PS) and semi-crystalline polymers (PE, PET, and sPS) in relation with their shrinkage stress and/or strain. For low orientations, it is found that the stress and strain can be simply related to birefringence. For semicrystalline polymers, the relationship is more complex. At high degrees of orientation, some modifications to the theories are required.
Efficient Coping with Production Breakdowns Using Knowledge-Base Approach
Zigmund Bluvband, Amos Shavit, May 1999
Injection molding product quality is affected by many process parameters. The usual trouble-shooting procedures suggest a list of possible corrective actions for each potential failure of a product, without taking into account possible side effects. There is one optimal corrective action, leading to the most stable process and product quality. This paper presents a methodology that helps the operator to select the most efficient corrective action, using Knowledge-Base (K.B.) approach, relying on a Y-shape matrix (failure-cause-solution) with theoretical rules and practical statistics.
Miscible Blends of Nylon 6 and TDAI, an Oligomeric Aromatic Nylon, with Improved Melt Flow and Moisture Resistance Properties
M.K. Akkapeddi, J. Glans, S.J. Chung, May 1999
A high Tg, aromatic nylon oligomer based on poly (tolyleneisophthalamide) (TDAI) was designed and evaluated as an additive for melt blending with conventional aliphatic nylons (PA 6 and PA66) to achieve miscible blends with improved Tg and property retention upon moisture equilibration. Blending only 10w% of TDAI in GF-PA6 and GF-PA66, a nearly complete retention of modulus and strength could be achieved at 50%RH, validating the general concept of wet Tg enhancement of nylons through miscible Tg-boosting additives. Moisture insensitive oxygen barrier properties could also be obtained in cast PA6 film. The oligomeric nature of TDAI contributes to improved melt flow in PA 6 and permits higher glass loading to give products with moisture-insensitive stiffness and dimensional stability.
Microstructural Effects on the Properties of Injection Molded Nylon 6 Nanocomposites
M.K. Akkapeddi, May 1999
Nylon 6 nanocomposites consisting of extremely thin, nanometer scale dispersions of platelet type silicates have been prepared and their injection molded properties and morphology have been investigated. The high surface area of such silicate dispersions contribute to a high reinforcement efficiency at low loadings, resulting in high specific modulus, strength and DTUL. However, such ultra-thin platelets cause some unusual structure development during the injection molding. Flow induced orientation of the platelets and an apparent surface nucleation promotes faster crystallization of nylon 6. Higher crystallinity was observed in the nylon 6 nanocomposites, particularly at the surface and in thin-wall moldings compared to the conventional nylon 6. The crystallization, skin-core morphology effects in the injection molded nylon 6 nanocomposites correlate well with the observed mechanical properties, weld-line and surface UV/ weathearing behavior.
Effect of the Addition of a Polycarbonate on the Cure of an Epoxy Thermoset System
M.J. Amaral, A. Espejo, A. Gonzalez-Alvarez, M. Arellano, May 1999
During the cure of a thermoset-thermoplastic blend two-phase morphologies may be formed. The phase separation process can be controlled by manipulation of the rate of polymerization of the thermoset system. In this work, the effect of the addition of different amounts of polycarbonate (PC) on the rheokinetics of an epoxy thermoset system is presented. The reactive system used was diglycidyl ether of bisphenol-A cured with 4-4 diaminodiphenylsulfone. The blends of the PC and the epoxy resin were prepared using two different procedures: (a) hot melt blending and (b) dissolution in a common solvent. The kinetics was followed by differential scanning calorimetry and the change in the rheological properties during the curing by dynamic rheometry.
Morphology Development in Carbon Dioxide Assisted Polymer Blending In Batch and Continuous Processes
M.D. Elkovitch, L.J. Lee, D.L. Tomasko, May 1999
The compatibility of individual homopolymers is one of the most important parameters influencing polymer blending. Often times blending involves components with vastly different viscosities and interfacial tensions. Supercritical carbon dioxide can be added to polymer melts as a processing aid such that effective polymer blending will occur. A blend system of a high viscosity polymethylmethacrylate (PMMA) and low viscosity polystyrene is analyzed in this work. Carbon dioxide has a higher affinity for PMMA than for polystyrene (1). Therefore, a greater plasticizing effect will occur for the PMMA than for the polystyrene. The improved results in polymer blending will be shown in this work. The morphology development of the polymer blends is analyzed in a high-pressure batch mixer and the continuous extrusion process.
Viscoelastic Properties of Multiphase Polymeric Blends
Paula Pieroni, Daniel Ercoli, Graciela Goizueta, Numa Capiati, May 1999
Rheological analysis of multi-phase systems is very difficult because the morphology is strongly related to the flow history. The small amplitude oscillatory shear flow does not affect the morphology and is very useful to predict the viscoelastic behavior of immiscible blends. In this work we study the dynamic rheological properties of Polypropylene based ternary blends with linear low density polyethylene and ethylene/propylene terpolymers of different viscosities taking into account the effects of changing the composition and concentration of the dispersed phase. The predictions of a constitutive equation for emulsions of viscoelastic fluids are also included.
Bubble Dynamics in Viscous Shears Flows
Moshe Favelukis, May 1999
The growth of a gas bubble in a viscous liquid in shear and extensional flows has been studied toward understanding polymer devolatilization. The experimental work was carried out in a Couette apparatus, which operates under vacuum. Air bubbles, which were formed, deformed and grown in a low molecular weight polyisobutylene, were photographed under shear. The experimental growth results indicate that the growth rate of a slender bubble increases as the shear rate increases and as the pressure decreases. These results confirm the existing theory, however they show that simple shear flow is much less efficient than simple extensional flow.
Evolved Gas Analysis of Polymer Decomposition Processes via Highly Integrated Thermal/Spectroscopic Measurement Techniques
J.B. Henderson, E. Post, E. Treser, Bob Fidler, May 1999
Simultaneous thermal analysis techniques, for example TG-DSC/DTA (Thermogravimetric-Differential Scanning Calorimetry/Differential Thermal Analysis), yield vital information on polymer makeup based on heat flow behavior and mass change characteristics during heating. These techniques offer little direct information, however, on exact composition of evolved gas products. It has recently been found quite powerful to combine simultaneous thermal analyzers directly in tandem with both Mass and FTIR (Fourier Transform Infrared) spectrometers. The challenge is effectively coupling the instruments such that optimized evolved gas analysis is possible. Practical applications of evolved gas analysis for polymeric materials include analysis of decomposition and aging processes, additives, residues, outgassing, desorption behavior and more. This paper will examine results of thermoanalytical experiments on polymeric materials via TG-DSC/DTA closely coupled with both a quadrupole mass spectrometer (QMS) and an FTIR spectrometer.
Advancements in Polymer Characterization Using Fast Response DSC at Elevated Temperatures and Pressures
Stephan Knappe, Elisabeth Treser, Bob Fidler, May 1999
Proper characterization of polymers by Differential Scanning Calorimetry (DSC) may be compromised when calorimetric transitions coincide or when components volatilize at the same time as critical transitions are expected to occur. To increase the utility of DSC for polymer characterization, it is highly desirable to minimize system time constant and improve signal-to-noise ratio in order to improve sensitivity and peak resolution. As well, operation under conditions of increased pressure may succeed in preventing unwanted volatilization, permitting resolution of certain transitions. This paper describes in detail specific polymer applications emphasizing the significance of DSC cell time constant reduction in terms of improved peak resolution as well as the importance of cell baseline stability throughout a broad temperature range and over increasing pressure conditions.
Stabilizers for Peroxydicarbonate Initiator Solutions
Peter Frenkel, Ted Pettijohn, May 1999
Liquid dialkylperoxydicarbonates are used as initiators in the PVC industry. Due to the thermal reactivity of these initiators, they require very low temperature storage, shipment and handling. At temperatures above 10°C, most undergo auto-accelerated self-induced decomposition. In other words, their self-accelerating decomposition temperature (SADT) is exceeded. New additives have been discovered which increase the SADT of the initiators. These additives effectively stabilize the product, making them safer to handle, store, and ship. The proprietary additives and a mechanism of stabilization will be discussed. We will also include a section concerning the implications these products have for future initiator formulation.
Fish Oil Polymeric Systems: Synthesis, Structure, Properties and Their Relationships
Fengkui Li, David Marks, Richard Larock, Joshua Otaigbe, May 1999
Fish oil or conjugated fish oil was copolymerized with divinylbenzene and norbornadiene or dicyclopentadiene using BF3·OEt2 as an initiator in an effort to develop useful biodegradable polymers with rationally designed structures from natural renewable resources. Dynamic mechanical analysis, DSC, TGA and nuclear magnetic resonance spectroscopy have been used to characterize the resulting fish oil polymers. The results show that viable fish oil products ranging from rubbers to hard plastics may be synthesized by changing the type and amount of the comonomers used. The fish oil products are thermosetting polymers having highly crosslinked structures, glass transition temperatures ranging from 50 to 130°C, room temperature modulus of about 109 Pa, and excellent thermal stability, making the products useful for applications where current biodegradable plastics are not useable.
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