bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of end‐group concentrations and molecular weight of poly(butylene terephthalate) by solid‐state fourier transform infrared spectroscopy
Authors: Kosky P. G. , McDonald R. S. , Guggenheim E. A. 
Published: May 2005

AbstractMolecular weight determination in poly(butylene terephthalate) (PBT) is hindered by the inherent difficulties of intrinsic viscosity (IV) determination in general and toxic solvents used in particular. In any case molecular weight does not include information as to the identity of end‐groups in the polymer chain. This report shows how the Fourier Transform Infrared method of Ward for PET can be adapted for alcoholic and acidic end‐group determinations in poly(butylene terephthalate) (PBT) and consequently for the number averaged molecular weight of PBT. A statistical analysis was performed on comparative IR‐ and IV‐derived molecular weight which revealed a correlation coefficient of better than 90 percent. The method is, therefore, recommended as an alternative to the standard IV technique, especially if simultaneous end‐group analyses are also required.
Recent advances in interpenetrating polymer networks
Authors: Sperling L. H. 
Published: May 2005

AbstractInterpenetrating polymer networks (IPN's) can be defined as a combination of two polymers in network form, at least one of which was synthesized and/or crosslinked in the immediate presence of the other. Historically, the science of IPN's began with the papers of J. R. Millar in 1960 on homo‐IPN's made from polystyrene, but the first recorded publication is a patent by J. W. Aylsworth in 1914. This latter system was based on phenol‐formaldehyde for one network, and sulfur cured natural rubber for the other network. Early academic laboratories interested in IPN's include the Frisch team at Detroit and SUNY, who soon added their former student, Danny Klempner, and Yuri Lipatov's team at the Ukranian SSR Academy of Sciences in the USSR, as well as the author's laboratory. More recent academic teams interested in IPN's include Douglas Hourston at the University of Lancaster, England; Robert Cohen at MIT; S. C. Kim at the Korea Advanced Institute of Science and Technology, Seoul, Korea; G. Meyer and J. M. Widmaier in Strasbourg, France; and many others. Numerous industrial laboratories are interested, noting that about 90 U.S. patients have been granted, most of them in the past ten years. Systems of special interest include the new thermoplastic IPN's, which are really hybrid materials between polymer blends and IPN's, and the IPN‐based RIM (reaction injection molding) materials. Other materials include the sequential IPN's and the SIN's, which have both polymers simultaneously polymerized, and the latex IPN's, which often exhibit core‐shell characteristics.
Inertia and gravitational effects in extrusion dies for non‐Newtonian fluids
Authors: Leonard William K. 
Published: May 2005

AbstractAn analysis is presented which allows the sheet or film die designer to estimate when inertial and gravitational effects are important. General theoretical equations are developed for end fed dies with arbitrary variation of the cavity cross sectional shape, cavity taper, slot length, and gap over the width. The method assumes viscous flow and a two dimensional approximation for the cavity flow. For fluid flow properties, it is assumed only that the apparent viscosity is a single valued function of the shear rate. In the important special case of constant die geometry and power law fluids, three dimensionless numbers plus the power law index are the parameters controlling the uniformity of flow from the die. Results are presented that illustrate when die orientations with respect to gravity and when fluid inertia are important. When they are not, simple expressions for die inlet pressure and uniformity index are given.
Energy absorption characteristics of polymeric foams used as cushioning materials
Authors: Miltz Joseph , Ramon Ori 
Published: May 2005

AbstractThe “Efficiency of Energy Absorption” (or “Efficiency”) and “Ideality” parameters were evaluated for several plastic foams and were found to be very useful in choosing an appropriate cushion for the protection of a specific product. The maxima in these parameters were found to be in the same range of stresses, when derived from dynamic measurements or from predicted stress‐strain curves based on previously proposed “Reference” and “Modified Boltzman Superposition” Models. For the rate independent foams the maxima in these parameters do not change with strain rate and can therefore be derived from slow, constant rate (“static”) experiments. For rate dependent foams however, the maxima from “static” measurements were found to be in a lower range of stresses than those derived from dynamic ones. As a result, slow rate compressive measurements do not predict well the behavior of the foams during impact and the use of the “Reference” and “Modified Boltzman Superposition” Models is required for good predictions. It was found that the suffer PS and PE foams attain maximum Efficiency and Ideality at higher stresses than the more flexible PUR foams.
Rotary injection reaction injection molding (RI‐RIM). Part II: Interfacial segregation of release systems
Authors: Briscoe B. J. , Khan M. B. , Richardson S. M. 
Published: May 2005

AbstractThis paper describes the shear imposed interfacial segregation of release systems for the facilitated attenuation of polyurethane (PU) adhesion to metal coun‐terfaces using a RI‐RIM system. It is shown that the migration rate of the dispersed release additives due to a shear imposed stress in the resin fluid is much greater than that arising from Fickian diffusion, thereby removing a vital constraint from conventional practice. The novel rotary injection RIM system is presented to simulate the on‐line injection and shear induced interfacial segregation in model PU/abherent systems. A wide range of recipes comprising single (liquids or solids) and multicomponent (liquid‐liquid and solid‐liquid) release materials were injected into the polymerizing resin mixture to provide cohesively weak and friable “particle” boundary layer assemblies at the PU/metal interface. An instrumented Blister Test was employed to evaluate the quality of the molded interfaces in terms of adhesion and the concentration distribution of the injected species in the final cured moldings was determined through high pressure liquid chromatography (HPLC). A comparison of the results on the shear modified and the compounded interfaces confirm an accentuated lateral migration of the additives to the interface resulting in an appreciable diminution in the adhesion of the system. Finally, transport models are suggested to account for the observed augmented transport.
Mechanical properties and behavior of open cell foams used as cushioning materials
Authors: Ramon O. , Mizrahi S. , Miltz J. 
Published: May 2005

AbstractIt is the purpose of the present publication to show that most of the phenomenological viscoelastic theories developed for bulk polymers can be readily adapted to plastic foams in order to evaluate their mechanical properties. In addition it will be demonstrated how the mechanical properties of open cell plastic foams can be predicted from a few simple compression and relaxation experiments.
Impact fracture toughness tests on polymers
Authors: Adams G. C. , Bender R. G. , Crouch B. A. , Williams J. G. 
Published: May 2005

AbstractA series of impact tests are described in which the plane strain fracture toughness, Kc1, of five different polymers is measured using a three point bend specimen at striker speeds up to 5m/s. At low speeds Kc1 is determined using the maximum load and a static analysis, but at speeds greater than 1 m/s the dynamic effects render the load signal unusable. For the higher speeds the fracture is timed using contact and crack propagation gages and the analysis is performed using the striker displacement at fracture. A dynamic analysis is used to convert this measurement to the true specimen displacement and Kc1 is determined from this. The apparent downward trends in the Kc1 results obtained, especially at speeds above 3m/s, are discussed.
Dynamics of a CSTR for styrene polymerization initiated by a binary initiator system
Authors: Kim Kee‐Jeong , Choi Kyu‐Yong , Alexander James C. 
Published: May 2005

AbstractThe steady state and dynamic behavior of a continuous stirred tank reactor has been analyzed for free radical solution polymerization of styrene initiated by a mixture of two initiators having different thermal stabilities. From the steady state analysis of the reactor model with a mean residence time as a bifurcation parameter, four unique regions of steady state solutions are identified in an operating parameter space for a given initiator feed composition. A variety of complex bifurcation behavior such as multiple steady states, Hopf bifurcation and limit cycles have been observed and their stability characteristics have been analyzed. The effects of feed initiator composition and the concentration of the initiator in the feed stream on the reactor dynamics are also presented.
Bulk and surface compression viscosities of high and low density polyethylenes
Authors: Aleman J. V. 
Published: May 2005

AbstractBulk compression flow of high density polyethylene (HDPE) and low density polyethylene (LDPE) have been measured at temperatures of 423 to 463K, pressure up to 150 MPa, and bulk compression rates of about 1.0 to 200.00 × 10−5 s−1. Bulk and surface compression modulus of elasticity (L and Ks), longitudinal bulk compression viscosity (ηL), and surface compression viscosity (η) are described as a function of compression rates (kv and ks), compression deformations (kv percent and Ks percent), and temperature (T). Bulk and surface compression flow activation energies are of the order of 40 to 100 KJ/mol and 3.84 KJ/mol, respectively.
Numerical simulation of the cast film process
Authors: d'Halewyu S. , Agassant J. F. , Demay Y. 
Published: May 2005

AbstractThe cast film process is studied and a numerical simulation is performed using a finite element method. Two dimensional equations involving the thickness and a mean velocity are used by considering the film as a thin layer. The process is assumed to be isothermal between the die exit and the quick cooling on the chill roll. The width of the film is computed iteratively as a free surface problem by means of a finite element method. The thickness distribution of the film is obtained by a finite volume method. This approach allows modeling of the well known “dog‐bone” or “edge bead” defect with a reasonable computation time.
Crystallization phenomena in the injection molding of poly ether ether ketone and its influence on mechanical properties
Authors: Hsiung Chang‐Meng , Cakmak Mukerrem , White James L. 
Published: May 2005

AbstractA basic experimental investigation of structure development in the injection molding of poly ether ether ketone (PEEK) is presented. It is shown that, dependent upon processing conditions, especially mold temperature, PEEK may be injection molded to form glassy or crystalline parts or parts consisting of intermediate structures such as a glassy surface and one with an internal crystalline link. In general, cold molds produce glassy parts and hot molds crystalline parts. This behavior is carefully characterized using optical microscopy, differential scanning calorimetry, and wide angle X‐ray diffraction techniques. The mechanical properties of these injection molded parts is characterized as a function of the crystalline and glassy contents and types of structural gradients developed in the parts.
Analysis of polymer blend morphology by transmission and reflection light scattering techniques
Authors: Belanger C. , Cielo P. , Favis B. D. , Patterson W. I. 
Published: May 2005

AbstractOptical inspection is a potentially powerful and practical tool to collect information on polymer blend morphology for on‐line quality and process control. This paper describes two approaches for the characterization of polymer blend materials by multiple light scattering. A quantitative evaluation of spectral turbidimetry (scattering of transmitted light) is presented and an adaptation of this technique for monitoring particle size, independent of the volume fraction is demonstrated. Such a procedure is applicable to materials in film form. A different approach is presented for the analysis of nearly spherical particles in optically thick samples: the diffuse reflection pattern surrounding the position of incidence of a focused light beam on the surface of the turbid medium is scanned by a single side imaging system. A spectral pseudo‐transmittance signal processing technique provides particle size information again independent of the volume fraction: Both techniques have been tested using well characterized polystyrene microspheres suspended in water as well as poly(methyl) (methacrylate)/polystyrene polymer blends.
Finite element analysis of dip coating with bingham fluids
Authors: Hurez P. , Tanguy P. A. 
Published: May 2005

AbstractA finite element analysis of the dip coating process with Bingham fluids is presented. The solution method for the viscoplastic flow problem was based on the augmented Lagrangian method allowing a rigorous treatment of the stress discontinuity. To compute the location of the free surface at equilibrium, an iterative method was used based on the arbitrary Eulerian‐Lagrangian approach in conjunction with mesh smoothing. Numerical predictions were validated against experimental data for the Newtonian limit case. Computations were then performed with Bingham fluids. The influence of yield stress on the meniscus flow Is discussed.
Birefringence–An important property of plastic substrates for magneto‐optical storage disks
Authors: Siebourg W. , Schmid H. , Rateike F. M. , Anders S. , Grigo U. , Löwer H. 
Published: May 2005

AbstractBirefringence is an important substrate property for optical data storage media. The basic definitions of birefringence and its relation to the chemical nature of polycarbonate are outlined. The polarizability of the monomer unit, expressed in the rheo‐optical constant and the degree of remaining polymer chain orientation, determines the level of birefringence in polycarbonate disk substrates. Based on this theory, the theory of blending materials with positive and negative rheo‐optical constants Is developed, and the current work with polycarbonate/polystyrene blends is reviewed. The biggest disadvantage of the reviewed system Js that only binary systems with low LCST (lower critical solution temperature) (<240°C) can be formulated. Finally, we report on successful development work of a single‐phase blend of a modified polycarbonate with a special styrene‐acrylonitrile copolymer. The experimental results are compared with the theoretical expectations, and the implications on the injection molding of disk substrates are discussed.
Thermotropic liquid crystalline halatopolymers
Authors: Ibidapo T. Adesanya 
Published: May 2005

AbstractDivalent metal (I.e.) Ba(2+), Ca(2+i), Mg(2+), Mn(2+), Cd(2+), Zn(2+), Pb(2+), and Sn(2+) salts of monovalent organic acids (i.e. p‐methoxycinnamic, cinnamic, p‐methoxybenzoic, and 4‐n‐butoxybenzoic) were synthesized via the double decomposition reaction from aqueous solution. Optical microscopy and differential scanning calorimetry (DSC) analysis showed that this series of salts formed nematic liquid crystals. DSC thermograms were characterized by broad nematic‐to‐isotropic transitions indicative of biphasic regions in which the nematic and isotropic phases coexist. These liquid crystalline salts were polymeric when melted due to ionic crosslinking which took place through the coordination of the divalent metal ion. Except Sn (2+) and Pb(2+), all the liquid crystalline halato‐polymers were spun into fibers.
Model‐Filled polymers. III: Rheological behavior of polystyrene containing cross‐linked polystyrene beads
Authors: Park M. , Gandhi K. , Sun L. , Salovey R. , Aklonis J. J. 
Published: May 2005

AbstractThe steady shear viscosity and dynamic moduli, at 180 and 200°C, of polystyrene composites, containing cross‐linked monodisperse polystyrene beads varying in diameter from 0.2 to 0.8 μm, are independent of bead size and cross‐link density, but increase with the volume fraction of beads. Steady shear viscosities exhibit power‐law regions up to 40% concentration of beads, but no yield stress. Storage and loss moduli are initially linear with frequency, on double logarithmic plots, with limiting slopes of 1.3 and 0.9, respectively. Uncross‐linked beads and beads cross‐linked with 0.1% divinylbenzene are destroyed by thermomechanical dispersion in the melt.
Optimizing blown film polyethylene using a merit function
Authors: Cantor Kirk M. , Harrison Ian R. 
Published: May 2005

AbstractThe extrusion of blown film polyethylene is a complex process characterized by a large number of interdependent process variables. In order to derive the set of process conditions necessary for a desired film solid state property, the processor normally utilizes a laborious trial‐and‐error method. In this work, a technique is described to establish more directly the set of extruder settings for producing film with an optimum value of a given property. Biaxial toughness was optimized in the present work, but the technique is applicable to any quantifiable film property.
Vortex formation in a dual‐cavity coat‐hanger die
Authors: Lee Kwong‐Yang , Wen Shu‐Heng , Liu Ta‐Jo 
Published: May 2005

AbstractThe effects of cavity shapes, particularly the expansion and contraction angles, and the Theological properties of polymeric liquids on vortex formation in the cuter cavity of a dual‐cavity coat‐hanger die have been examined. For power‐law fluids, a vortex may appear in the expansion side of the outer cavity, and the size of the vortex is influenced by the expansion angle, the power‐law index, and the Reynolds number. Two viscoelastic fluids were used in the flow visualization experiment; for an aqueous polyacrylamide solution, a vortex may appear in the contraction side of the outer cavity and this vortex is influenced by the contraction angle and the fluid elasticity, but no vortex was observed for a Boger fluid.
A predictive model for the effects of thermal history on the mechanical behavior of amorphous polymers
Authors: Shay R. M. , Caruthers J. M. 
Published: May 2005

AbstractThe effects of thermal history during formation on the mechanical behavior of amorphous polymer solids must be part of a constitutive description for polymers in order to enable efficient design of manufacturing processes. A nonlinear, thermoviscoelastic constitutive equation for amorphous polymers has been previously derived via the rational thermodynamics framework, where the dissipation is assumed to occur on a material timescale that is controlled by the non‐equilibrium entropy, In this paper we report on the predictions of this constitutive equation for poly(vlnyl acetate). The material properties required by the constitutive model were determined for poly(vinyl acetate) from PVT and linear viscoelastic shear and bulk moduli measurements. Predictions of specific volumes during isobarfc cooling from the rubber and nonlinear uniaxial stress‐strain curves just below Tg are in reasonable agreement with experimental data. The model predicts that samples cooled below Tg and then isothermally annealed for specified times will exhibit yield stresses that increase with Increasing annealing time, as well as the familiar effects of changes in temperature and strain rate on the uniaxial stress‐strain and yield behavior. Shortcomings and potential improvements in the model are discussed.
The morphology of extruded blends containing a thermotropic liquid crystalline polymer
Authors: Blizard Kent G. , Federici Carlo , Federico Olimpia , Chapoy L. Lawrence 
Published: May 2005

AbstractThree different polymer blends consisting of an isotropic matrix and a ther‐motropic liquid crystalline polymer (LCP) as the reinforcement were extruded. Polycarbonate (PC) and polyetherimide (PEI) were the two matrices, and the LCPs used were Vectraw A950 of Hoechst‐Celanese, a copolyester of hydroxybenzoic and 2,6 hydroxynaphthoic acids and an LCP of Granmont Inc., a condensation polymer of terephthalic acid, (l‐phenylethyl)hydroquinone, and phenylhydroqui‐none. These extrudates were characterized by a quantitative morphological technique to determine the percentage of LCP present as fibrils and the average domain diameter. These experimental observations were then coupled with the component Theological behavior and a simple heat transfer analysis to explain the morphology and property differences between the blends. Blends with the Granmont LCP showed no appreciable increase In the quantity of fibrils with draw ratio, for example, whereas the amount of fibrils in Vectra® blends tended to increase to a plateau with draw. The tensile modulus of the blends agreed well with composite theory, with average fibril moduli of 24.6 GPa and 23,3 GPa for Vectra® and the Granmont LCP, respectively. These differences can be explained in terms of the cooling behavior of the LCPs.
Iterative boundary pressure reflection method for the simulation of injection mold filling
Authors: Lee Ho‐Sang , Sin Hyo‐Chol , Kim Sang‐Gook 
Published: May 2005

AbstractAn Iterative Boundary Pressure Reflection (IBPR) method has been developed to improve the accuracy of the flow front generation and transient mold filling simulation in injection molding. The method iteratively calculates the virtual pressure reflection, either positive or negative, at the impinging melt front nodes which are to be relocated subsequently according to the new pressure field. The scheme is formulated into a finite element program using a power‐law model and applied to the filling of polystyrene melts injected into an edge‐gated circular cavity and a variable‐gap‐thickness cavity with an insert. The calculated results show very good agreement with the experimental results of the previous study by others in the position of the advancing melt fronts at each time step, weldline location, and pressure distributions.
Predicting molding forces in SMC compression molding
Authors: Castro J. M. , Tomlinson G. 
Published: May 2005

AbstractA model relating molding force, compression speed, and part thickness, to material properties, part size, and processing conditions (mold and charge temperature) is necessary, to determine the ranges of closing speed feasible, when molding a predetermined part with a press of given capacity (tonnage). The faster we can close, in principle, the faster reacting systems we can run in a given press. A model has been developed to predict the force required for compression molding of SMC under non‐isothermal conditions. The model requires two material rheological parameters, namely, the material resistance to extension η and a friction coefficient λ. A method has been developed to measure these coefficients. Preheating the charge is an attractive way of decreasing the molding force required. Also higher molding temperatures would give lower friction and thus lower molding force.