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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Dipolar Dynamics in Miscible Polymer Blends
The reorientational dynamics of dipoles in PVDF/PMMA blends were investigated by dielectric relaxation spectroscopy (DRS). Various relaxation processes associated with different morphological regions were identified. Phase separation during crystallization was monitored in-situ by DRS. In addition to the relaxation related to the glass transition, a relaxation which cannot be attributed exclusively to the crystal-amorphous interphase is found in the blends. An interpretation of experimental observations is based on cooperativity and morphological considerations.
Trouble Shooting Cavity to Cavity Variations in Muticavity Injection Molds
Significant differences are commonly seen between parts molded in multicavity injection molds. The elimination of these variations is complicated by the large number of variables existing within the mold, the injection molding process and the material. This paper presents a means of isolating and quantifying the primary causes of these variations. By isolating the causes the molder can more effectively and efficiently address the differences between parts molded in different cavities and thereby maximize productivity.
Flow Fields of Polymer Melt Flowing through Wedge Converging Channel
Simple formulae are proposed for the velocity and extensional strain rate profiles for a power-law fluid in a converging wedge channel. Trajectory images are obtained of a colored strand in the high density polyethylene melt flowing through a tapered slit die. The theoretically predicted trajectories are in reasonable agreement with the experimental results. The varying trends of the extensional strain rate with the radial and angular positions in the converging channel are then theoretically revealed.
Case Studies of Plastics Failure Related to Improper Formulation
Troubleshooting of plastics failures often requires chemical analysis to determine if the formulation is a contributing factor. Examples of failures in product performance or development associated with incorrect or improper chemical composition of formulations include (1) adhesive problem due to improper order of films in a multilayer system; (2) hardener left out of an adhesive; (3) delamination of tin coating from copper due to adhesive tape wrap; (4) stiffening of grease lubricating a moveable screw in a servo motor; (5) unintentional color in a portion of an electrical cable.
Isomers and Isomerization Processes in Poly-Anilines
The extraordinarily important potential role of isomers in determining the electronic, magnetic, optical, structural and mechanical properties of poly-anilines, including polyaniline is presented. Positional and cis/trans isomers and isomerism processes, some of which occur relatively slowly even at room temperature in solution are reported for the phenyl/phenyl end-capped dimer and the phenyl/amino end-capped tetramer (emeraldine oxidation states).
Kinetics of Non-Isothermal Crystallization of Syndiotactic Polypropylene: Avrami, Ozawa, and Kissinger Approaches
The kinetics of non-isothermal crystallization of syndiotactic polypropylene was investigated using a differential scanning calorimeter (DSC). Analysis of the data was carried out using the well known Avrami and Ozawa equations. The activation energy for molecular transport based on non-isothermal melt crystallization was calculated using the Kissinger method.
Performance of Rubber-Modified Cyanate Ester Matrices
Cyanate ester resins were modified with epoxy-terminated butadiene acrylonitrile rubber (ETBN) and impregnated into woven glass fabric. Mode I and mode II interlaminar fracture toughness of the cured laminates were evaluated as a function of rubber concentration. Mode I fracture toughness increased almost twice that of the unmodified system, while mode II fracture toughness remained essentially unchanged. Composite samples were subjected to aging experiments in water and the absorption behavior and thermal performance were characterized.
Thermally Conductive Thermoplastic Materials
Thermoplastics have made steady gains in the replacement of metals in a wide variety of applications. One of the last areas in which thermoplastics have not been effective in replacing metals has been in applications where thermal conductivity is required. Central to the development of these materials is an understanding of the heat transfer requirements in these applications. A simple model will be presented in which the heat transfer requirements for thermally conductive materials can be understood. Through the use of various filler systems, materials have been developed with thermal conductivities from 1 to 10 W/m°K.
Instrumenting the Elmendorf Tear Test
The Elmendorf tear test is widely used to evaluate tear strength of blown and cast films. Yet, the tear strength value does not directly relate to toughness, energy, or, indeed, any other true material property. Development of structure-property relationships are very difficult when the property one attempts to measure is so ill-defined. Furthermore, the Elmendorf value does not differentiate between initiation and propagation events. In this paper we describe a setup for instrumenting the Elmendorf tear test so that the information that one derives from the test is analogous to an instrumented impact test.
Plastic Part Design - Lessons Learned
Five different parts and assemblies that seemed to have been designed well but failed to meet the functional requirements after production are analyzed for the reasons of the failure. These are compatibility of materials, long term stress cracking, and effect of tool design on the part properties. The theory behind the failures is discussed briefly. Finally the solution to alleviate these problems is discussed.
Metal-Polymer Interfaces in Polymer-Based Electronic Devices
A number of degradation mechanisms in polymer-based light emitting devices have been studied. It was found that interfacial chemistry occurs between indium tin oxide (ITO) and precursor poly(p-phenylene-vinylene) (PPV) forming InCl3, which enhances the rate of conversion to PPV but leaves the polymer slightly p-doped. Electron flux on/through PPV films damages mainly the vinyl linkage, probably causing scission with subsequent cross-linking or bond formation with oxygen species.
Thermoplastic Elastomers, Four Decades of Innovation
The successful commercialization of Polyurethane TPEs and elastic fibers in the late fifties initiated the move toward the establishment of thermoplastic elastomers as a new class of polymers. In the same decade the styrene block polymers were introduced and the dynamic vulcanization process was discovered. In the second decade, the copolyesters made their entry into the engineering resin applications and in the third decade the thermoplastic vulcanizates kicked this new class of polymers into reality.
Investigation of Cavity-To-Cavity Variations in Multi-Cavity Tools
Cavity pressure is widely accepted as a sensitive indicator of the injection molding process and can be used as one of the process parameters that control the overall molding cycle. This paper presents the investigation of the role of cavity pressure in predicting part quality, effect of process parameters on part weight and cavity pressure, and the dependence of nozzle melt temperature on process parameters. In addition, the effect and the presence of different runner systems in a multi-cavity tool and its subsequent effect on the part quality and performance are also investigated.
Interfacial Free Volume Measurements of Epoxy on Aluminum by PALS
Positron annihilation lifetime spectroscopy(PALS) characterizes free volume in polymers. Numerical integral transform methods(CONTIN program) extract continuous distributions of free volume cavities. An intermediate lifetime was found in epoxy films on chrome conversion coated (CCC) Al substrates and attributed to positron annihilation at the interface. Analogous lifetimes were identified for epoxy polymer/SrCrO4 particles and epoxy films/CCC substrate specimens. Applications include studies of permeant interactions at polymer interfaces.
Novel Oil Resistant Thermoplastic Vulcanizates
The hydrocarbon oil resistant thermoplastic elastomers that are at present commercially available are not suitable substitutes for oil resistant thermoset rubbers such as nitrile butadiene rubber (NBR). The properties of a thermoplastic vulcanizate produced by the dynamic vulcanization of NBR in a polyester thermoplastic are shown to be comparable to those of an equivalent hardness thermoset NBR.
Integration of Models to Predict Phase Behavior in Polymer-Polymer Systems
The Phase Computer software package is designed to predict the phase behavior of polymer-polymer systems and can run on a Personal Computer. The vertical integration and adaptive dynamic programming techniques with a rule based expert system was used in the development. RDBMS principles were used in the design of the databases for the binary interaction parameters, atomic parameters and molecular parameters. The mathematical models included are the binary interaction parameters, atomic parameters and molecular parameters.
Fluidized Bed Degasification for Removing Unreacted Monomers in Continuous Mass Polymerization
The feasibility of a fluidized bed degasifier design where removal of polymer residuals to low levels as expected by the regulatory agencies is evaluated. Mass transfer models are needed to quantiate the devolatilization efficiency. The relative importance of the diffusive and convective transport mechanism varies as a function of the flow physics in the fluidized bed degasifier. The conditions of operation suggested are sub glass transition temperature of the polymer and subatmospheric vacuum pressures.
Spreadsheets and Simulation in Polymer-Polymer Phase Diagrams
The compositional window of miscibility of two terpolymers can be calculated using a spreadsheet. The results are presented as a function of the compositional mismatch. The @RAND key was used to demark the miscible regions from the immiscible ones in the entire compositional range (n x m x k x 1 or n4) of the terpolymer. The computations were completed in cN or n time. The spinodal for miscible systems can be constructed and the LCST and UCST behavior captured.
Failure Analysis Models for Polyacetyl Molded Fittings in Plumbing Systems
Plumbing fittings molded from polyacetal resins have been studied after removal from service. Methods of failure analysis will be reviewed and failures will be correlated with time in service and water chemistry. The progression of failure will be described and related to the calculated stresses in the fittings.
New Twin Screw Element Design for Elastomer Compounding
A new mixing element design reduces the shear heat buildup normally seen with elastomer based compounds. This enables mixing these formulations at rates not achievable with standard design elements. The geometry of this element retains the general self-wiping characteristics usually found with fully intermeshing, co-rotating twin screw compounders, yet reduces the maximum pressure seen in the apex area. Process examples demonstrate the different responses seen with these mixing elements versus standard design elements.
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