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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Comparison of Three Methods to Measure the Elongational Viscostiy of Polymer Melts: Entry Flow, Fiber Spinning and Uniaxial Elongation
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.
Linear Viscoelastic Properties of Polymeric Suspensions
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 ?."
Chemical Assessment of Automotive Clearcoat Weathering
The top, clearcoat layer of an automotive paint job protects the under layers while maintaining a beautiful appearance for the life of a car. To determine clearcoat durability, effects of the weathering protocol, of the physical and chemical transformations and effects on the appearance must be considered. To this end, we will describe photoacoustic infrared (PAS-IR), and ultraviolet (UV) technologies and UV microspectroscopy to assay the changes in chemical composition produced in clearcoat paint systems by weathering.
A Thermo-Viscoelastic Model for the Modulus of Epoxy during Cure
The cure kinetics for a commercial epoxy have been established and the influence of the degree of cure on the glass transition determined. Time-temperature and time-conversion superposition principles have been built into a model that successfully predicts the development of the viscoelastic properties of the epoxy during isothermal cure from gelation to vitrification
Compatibilization of PET/HDPE Blends
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.
Contribution of Flow Deformation to the Shrinkage of Injection Molded PVC
The viscoelastic nature of PVC can not be ignored during the injection molding process. Strains imposed on the compound during the injection stage display recovery dynamics that are indicative of the temperature at which the strains were imposed. A mathematical model, employing approximate" time-temperature modulus relationships provided the basis for interpreting the shrinkage data. A distribution map of the various relative temperatures attained within the part during injection was determined."
Double Bubble Tubular Film Extrusion of Polybutylene Terephthalate-Polyethylene Terephthalate Blends
A technology has been developed to produce biaxially oriented films of blends of polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) using double bubble tubular film extrusion. The mechanical instabilities and the mechanisms associated with their sources of occurrence are described. The films have been structurally characterized by wide angle X-ray diffraction and optical techniques. The structure of the film is related to processing conditions.
Structure Development in Melt Processing Polypropylene, Polypropylene-EPM Blends and TPEs
Fibers have been melt spun from polypropylene and its blends with ethylene propylene rubber, as well as polypropylene based thermoplastic elastomers under various conditions. The spinline stresses as well as kinematics have been measured. The fibers have been structurally characterized using wide angle x-ray diffraction and birefringence and the results interpreted.
Transient Start-Up Flow in a Modular Co-Rotating Twin-Screw Extruder
A model for flow start-up of a Newtonian liquid in an initially empty modular co-rotating twin screw extruder is developed. The changes of length of fill in front of the die and kneading disc block elements and output flow rate with time were predicted for various modular screw configurations. Experiments were also carried out on a laboratory modular machine with windows to verify the predictions. Generally, good agreement with the flow analysis was found.
A Comparative Study of Fiber Breakage in a Buss Kneader, Modular Co-Rotating and Counter-Rotating Twin Screw Extruders
The breakage of glass fibers was measured for several different types of continuous mixers including (i) Buss Kneader (ii) modular intermeshing co-rotating twin screw extruder (iii) modular intermeshing counter-rotating twin screw extruder. Comparisons are made using different screw configurations, loadings, different feeding ports and mixing elements. Downstream feeding of glass fibers and milder screw configuration favor less breakage of glass fibers.
Ultrasonic Thickness Gauge for Multi-Layer Plastic Fuel Tanks
A newly developed instrument, the Echometer measures the thickness of a barrier layer in multilayer polyethylene fuel tanks. Measurement by conventional pulse-echo ultrasound fails for thin barriers due to the large and highly frequency-dependent attenuation in polyethylene. The present instrument instead uses tone-burst excitation. Echo arrival time determines barrier depth, and frequency of minimum amplitude determines barrier thickness. Similar techniques may be applied to other layered plastic structures.
Orientation Determination Using Birefringence and Spectroscopic Techniques
Techniques for the measurement of orientation of biaxially oriented films, sheets, and shapes using birefringence measurements based on oblique incidence of a polarized multiwavelength beam and FTIR spectroscopy in both transmission and reflection modes are presented. It is shown that sufficiently precise values can be obtained for biaxial birefringences and orientation functions, and that these techniques can be used for monitoring orientation processes as well as to control the quality of oriented articles.
Efficient Coping with Production Breakdowns Using Knowledge-Base Approach
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.
Photostabilization of Polycarbonate-Styrenic Blends
A new HALS technology has been developed which provides for improved light stabilization of pigmented PC-ABS blends. Significant improvements in color stability and impact strength retention have been observed for PC-ABS systems subjected to accelerated weathering xenon arc test conditions. The new HALS technology is non-interacting with the PC-styrenic blend during melt phase extrusion compounding, as observed by capillary rheometry measurements of the stabilized polymers.
Modeling of Rheological Behavior of Immiscible Polymer Blends Undergoing High Deformation Flows
Non linear rheology of a mixture of two immiscible viscoelastic fluids undergoing high deformation flow was considered. Using Grmela's approach of compatibility of dynamics with thermodynamics, we derived a set of highly non-linear governing equations that take into account particles breakup, coalescence and the time evolution of the complex interface between the two mixture components. The proposed model recovers previous models such as Doi-Otha, Grmela and Ait-Kadi and Lee and Park models.
Failure Analysis Case Studies, Part I: Effect of Processing Conditions and Part Design
In this paper, some case studies are presented to illustrate the effect of processing/assembly conditions and part design on product failure. Fractography was intensely used in these investigations. Nevertheless, mechanical analysis was occasionally used. The first case illustrates the role of assembly conditions in product failure. The second case shows the effect of part design. The third case describes the combined contribution of processing/assembly conditions and part design in product failure.
Maintaining the Thermal Balance Core to Cavity: The Key to Cooling Efficiency
Achieving parts with maximum dimensional stability coupled with minimum cycle times, is a goal of most molders. Previous studies have shown that a majority of heat contained in the molded part is removed through the core of a mold. Application of high strength, high thermal conductivity copper alloys to core, cavity, and gate areas, has led to some revelations. These data shed new light on the effect of change in temperature vs. change in thermal conductivity.
Mechanism of Organotin Stabilization of Poly(Vinyl Chloride). 4. PVC Stabilization by Alkyltin Alkyl Mercaptopropionates
The stabilization effect of alkyltin 2-ethylhexyl mercaptopropionates was studied by the measurement of color change on heating a PVC formulation.
Bubble Dynamics in Viscous Shears Flows
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.
How to Work with the Trade Press - Eight Keys to Getting Your Releases and Papers Published
Nothing can be more rewarding (or frustrating) than working with a trade magazine's editorial department. A solid working relationship with the trade press enables individuals and companies to deliver their business and technological news, ideas, accomplishments and opinions to the masses in a timely manner and with relative ease. A basic understanding of how trade press editors perform their duties and how editorial departments function allows business marketers to achieve their goals. What follows are eight key points that will help you put your best foot forward in the trade press.
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