bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat transfer to molten polymers
Authors: Griffin O. M. 
Published: December 2004

AbstractThe processing of polymers and other solids, such as waxes and acids, often requires the melting of a bulk or granular charge before its introduction into a process stream. Two approximate techniques for relating heat transfer and melting rates are presented here and the shielding effect of the melt formation is considered. The heat available for melting is sometimes remarkably decreased by the heat carried away by the flowing melt. Means are presented for quantitatively determining the shielding or sensible heat effect of the film. The thermal efficiency of the phase transformation process is discussed, and the effects of heat loss to both increased bulk temperature of the flowing melt and conduction in the solid are demonstrated. A comparison with experiment is made using temperature and melt flow data for polyethylene and polyoxymethylene. Heat transfer coefficients and melting correlations useful in practice are presented.
Structure‐property relationships of chlorinated polyethylenes
Authors: Kalfoglou N. K. , Williams H. L. 
Published: December 2004

AbstractThis experimental study of suspension‐chlorinated linear polyethylenes (CPE), (degree of chlorination 25 to 48% Cl), covers dynamic mechancial behavior at 3.5 and 110 Hz in the temperature range − 100 to 120°C. The semicrystalline samples, with a maximum degree of crystallinity of 25%, showed the main relaxations α and β. The effect of thermal treatment was examined. In the amorphous specimens, in addition to the Tg relaxation, other low temperature damping peaks were observed. The mechancial spectra indicate structure heterogeneity and increasing stiffness with increasing chlorine substitution. For the most prominent β relaxation, the apparent activation energy was determined from the frequency shift of tan δ and E″ maxima. The effect of structure, crystallinity and frequency on Young's moduli are also discussed. For the amorphous γ ray‐Crosslinked elastomeric samples the photoelastic properties were examined at near equilibrium conditions between 30° and 80°C at various degrees of crosslinking. The polarizability anisotropy of the optical link and the Mooney‐Rivlin elasticity constants were determined and an attempt was made to relate the result to the specimens' structure. A compatibility study was also made for a 42% Cl, CPE/high cis polybutadiene polyblend. The damping mechanical spectra indicate a noninteracting system whose Young's moduli can be correlated with those of the pure components using a phenomenological model proposed by Takayanagi.
The effect of molecular weight distribution on polyethylene film properties
Authors: Perron Peter J. , Lederman Peter B. 
Published: December 2004

AbstractPolymer molecular weight heterogeneity affects the rheological properties of polymer melts such as melt viscosity, fracture and die swell. These rheological properties affect the conversion of the polymer from the bulk resin state to its final usable form. In this particular study, the effect of molecular weight distribution on polyethylene blown film characteristics was studied. The effect of the molecular weight heterogeneity on the rheological characteristics of the polymer in the molten state and its effect on the film properties is presented.The properties studied included film gloss, haze, tear resistance and film impact strength.This study shows that broadening the molecular weight distribution increases haze and reduces film gloss. Further, it was shown that a linear relationship exists between film gloss and external haze. Both values are measures of surface irregularities in the film which are affected by the drawing characteristics of the polymer.A broader molecular weight distribution results in increased impact strength as measured by the Dart Drop Impact Test. This is, it is believed, a result of the increase in long chain branching of the higher molecular weight fractions of the polymer which cause a higher degree of molecular weight entanglement at the branch sites. In contrast the tear strength is reduced as the molecular weight distribution broadens because of the low molecular weight fraction in the broad spectrum material which tend to decrease resistance to tear.
Energy transport to molten flowing polymer systems: II. Analysis of data and development of temperature profiles with axial length
Authors: Saltuk Ismail , Siskovic Nandor , Griskey Richard G. 
Published: December 2004

AbstractEnergy transport to molten, flowing polymer has been studied. Experimental temperature profiles were determined at various axial lengths. These data are both precise and reproducible. Viscous dissipation was found to be a significant factor in these systems. In addition, sizable thermal expansion cooling effects were noted. It was also shown that the effect of viscous dissipation on Nusselt number was a function of Graetz number. At high Graetz numbers viscous dissipation had a sizable effect that declined to negligible proportions at Graetz values of 7 or less. Prior theoretical treatment of temperature profile development is shown to be only qualitatively correct.
Strain ratio and volume change during tension and compression creep of thermoplastics
Authors: Mallon P. J. , McCammond D. , Benham P. P. 
Published: December 2004

AbstractCreep tests up to 106 seconds in tension and compression were conducted on polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), and polypropylene (PP). Measurements of longitudinal and lateral strain provided values for tension and compression strain ratio. These increased with time and stress for PMMA and PVC from about 0.38 to 0.44. The results for PP increased from 0.44 to above 0.5 in. tension and showed a decreasing ratio in compression, which suggested a time and stress dependent structural change. Volumetric strain was computed from the linear strains and plotted against stress and axial strain. Except at 102 seconds, the relationships were non‐linear up to volumetric strains of about 0.3% and in the cases of PMMA and PVC there were greater changes of volume in tension than compression.
Scanning electron fractography of lap‐shear joints
Authors: Wilcox Roy C. , Jemian Wartan A. 
Published: December 2004

AbstractFracture surfaces of Epon 901/B‐3 bonded aluminum alloy joints in the lap‐shear configuration were studied using scanning electron microscopy. Major differences in the appearance of the fracture surface from those reported (8) for tensile loaded joints at 23°C are produced either by cyclic loading at 23°C or a change in test temperature to −196°C. Fracture in tensile loaded joints at −196°C is a brittle single step process in the opening mode in which rapid crack extension occurs throughout the joint with very little adhesive flow. Tensile fatigue fracture at 23°C is in the opening mode but crack extension is complicated by extensive adhesive flow throughout the entire joint.
Copolymerization of caprolactam with polyoxybutylene diamine
Authors: Shalaby S. W. , Reimschuessel H. K. , Pearce E. M. 
Published: December 2004

AbstractNylon 6‐polyoxybutylene block copolymers were prepared by reacting polyoxybutylene diamine with caprolactam in the presence of phosphoric acid. The copolymerization was carried out in a Helicone‐type reactor and the effect of time, temperature, and caprolactam concentration on the properties of the products was recorded. Differential Scanning Calorimetry studies of the products suggest the presence of both the ABA and AB types of sequences, where A and B represent nylon 6 and polyether blocks, respectively. Dynamic mechanical measurements of typical copolymers revealed the presence of at least two different nylon moieties. The melt rheology data reflect a general increase in the pseudoplasticity of the copolymer with the increase of the polyether content. Increases of the polyether content in the copolymer result in an increased elongation and a decreased tensile strength and modulus.
A numerical simulation of the cavity filling process with PVC in injection molding
Authors: Berger J. L. , Gogos C. G. 
Published: December 2004

AbstractFilling cold mold cavities with hot polymer melts at high pressures is of great practical interest. The transport approach to this process of solving the general equations of change with suitable equations of state to describe the flowing material has been largely ignored. No analytic solution is possible, and the non‐steady state flow adds a dimension which makes digital computation discouraging because of the core storage and execution time requirements.The mold filled in this simulation is a disk which hot polymer melt enters through a tubular entrance located at the center of the top plate. The tube is 2.54 cm. long and has a radius of 0.24 cm. The plate separation and outer radius of the disk cavity may be varied. A constant pressure applied at the entrance of the tube causes the flow. The cavity walls are kept at various low temperatures. The reported results are for rigid polyvinyl chloride (PVC).The general transport equations, i.e. continuity, momentum, and energy, for a constant density power law fluid are used to solve the flow problem. Convergence to the differential solutions is guaranteed but since a lower limit was imposed on the time increment by the core storage limit of the computer facilities (27K) and long execution times, all results are semiquantitative for the problem as stated.Using the results obtained it is possible to predict “fill times”. The formation of a frozen polymer skin as the cavity fills may be followed via the velocity profiles. The temperature profiles which reflect cooling and the amount of viscous heat generated provide the basis for studying resin thermal degradation effects.Finally, because so much of the total pressure drop is disispated in the entrance tube, and so much viscous heat is generated there, this study indicates that the design of the gate and runner system is perhaps the most important facet of success in mold filling.
Evaluation of the smoke and flammability characteristics of polymer systems
Authors: Imhof L. G. , Stueben K. C. 
Published: December 2004

AbstractUsing Oxygen Index and the XP‐2 test to measure flammability and smoke characteristics, a broad spectrum of thermoplastic and thermoset polymers, both commercial and experimental, were investigated to elucidate the effect of structure on fire properties.In general, polymers with aliphatic backbones are very flammable, but their tendency to generate smoke is minimal. The addition of flame retardants, especially halogen compounds, while reducing their tendency to burn, increases the evolution of smoke. Halogen‐containing polymers are usually non‐flammable, with high Oxygen Indices, but display high smoke generation. Polymers containing an aromatic group in the side chain, such as polystyrene, are both highly flammable and high smoke producing. However, polymers with the aromatic group in the main chain, such as polysulfone, polycarbonate and polyphenylene oxide, are intermediate in both Oxygen Index and smoke generation.After investigation of the various test methods available, it is concluded that no one test will be satisfactory to measure the flammability characteristics of polymers and that a combination of methods must be used.
Variables affecting parison diameter swell and their correlation with rheological parameters
Authors: Henze E. D. , Wu W. C. L. 
Published: December 2004

AbstractAn important factor in the selection of blow molding resins for producing handled bottles is the effective diameter swell of the parison. Ideally, the diameter swell is directly related to the weight swell and would require no separate consideration. In actual practice, the existence of gravity, the finite parison drop time and the anisotropic aspects of the blow molding operation prevent reliable prediction of the parison diameter swell directly from the weight swell.The parison diameter swell is a complex function of the weight swell, the rate of swell and the melt strength. Elements of this function are presented which show the effect of extrusion rate, parison drop time and parison weight.A technique is presented which allows the estimation of local weight and diameter swell ratios. Their direct relationship is confirmed by data obtained on several blow molding resins. The relationship between weight swell and diameter swell is definitely anisotropic.A mathematical model for swell is proposed which incorporates experimentally determined rate constants and swell coefficients. Correlations are given which suggest fundamental relationships between these derived coefficients and basic variables such as resin properties or process conditions. The model's predictive capability is demonstrated by using it to back calculate parison dimensions.
Poisson's ratio and the deflection of a viscoelastic plate
Authors: McCammond D. , Turner S. 
Published: December 2004

AbstractA new method for the measurement of the Poisson's Ratio function of the more rigid plastics is described. The deflection of a freely‐supported circular plate under uniformly distributed load is combined with modulus data obtained in an independent experiment. The apparatus is described, the validity of the relevant elastic stress‐strain formulae are discussed and the results obtained on PMMA and PVC are compared with other published values. It is concluded that this method is at least as accurate as the alternatives, all of which have particular deficiencies, and that it is possibly superior in some respects.
Parison material distribution: Viscoelastic and programming effects
Authors: Blower Kenneth E. , Standish Norman W. 
Published: December 2004

AbstractBlow molding of high performance bottles—including carbonated beverage bottles—requires close control of material usage and distribution. Two parameters—polymer viscoelasticity and mechanical/electronic programming—are investigated to determine their influence on weight distribution within the extruded parison. Barex® 210 Resin is utilized in a study of polymer swell and drawdown forces and the changes in material distribution that occur due to melt temperature, extrusion time, parison length, and weight. A system for multipoint mechanical/electrical parison programming is described and its influence on material distribution determined. This technique enables the blow molder to vary the parison material distribution for high performance and economical resin usage.
Impact reinforcement of poly(vinyl chloride)
Authors: Petrich Robert P. 
Published: December 2004

AbstractSeveral theories have been advanced to explain the toughening of glassy plastics by rubbery modifiers. These have been based primarily on studies of high impact polystyrene or ABS systems, where the crazing mechanism has been shown to be most applicable. In the present study, the effects of MBS (methacrylate‐butadiene‐styrene) impact modifiers on PVC have been studied, utilizing both physical and microscopic techniques. Tensile test results indicate that a primary contribution of the modifier to increased toughness is a lowering of the yield stress of the PVC. Electron microscopic studies and density determinations on strained samples indicate no crazes in these MBS‐modified PVC systems. These results suggest that the mechanism of impact reinforcement in PVC is based on the enhancement of localized yielding in the vicinity of the rubbery modifier particles.
Strain hardening equation and the prediction of tensile strength of rolled polymers
Authors: Bahadur S. 
Published: December 2004

AbstractA number of thermoplastic polymers were tested in tension to investigate their strain hardening behavior. A strain hardening equation has been proposed in terms of the true stress, true strain and two constants σo and m. The three material constants, viz. σo m and the true fracture strain, are shown to be adequate to describe completely the material's nonlinear viscoelastic or the so‐called “plastic” behavior. The true stress‐strain data for the polymers rolled to varying amounts of cold‐work fits the strain hardening plot of the unrolled material. The same strain hardening equation, therefore, applies to rolled materials as well. The procedure for predicting the tensile strength of rolled materials is given.
Chlorinated polyethylene modification of blends derived from waste plastics. Part II: Mechanism of modification
Authors: Locke C. E. , Paul D. R. 
Published: December 2004

AbstractPrevious publications have shown that the stress‐strain behavior, especially ductility, of some incompatible polymer blends are greatly improved by the addition of slurry produced chlorinated polyethylenes (CPE). This improvement is greatest for blends containing polyethylene and PVC. The most effective CPE's have some residual polyethylene crystallinity and may be described as block‐like polymers with ethylene sequences and chlorine containing sequences. It is postulated that CPE addition improves the blend properties by increasing the adhesion between domains in the blend via interactions with the blend components. This hypothesis was explored by thermal analysis, dynamic mechanical testing, adhesion studies, and microscopy. It is concluded that the interaction of CPE with polyethylene derives from compatibility of rather long methylene sequences in CPE with the polyethylene which results in good adhesive bonding. The interaction of CPE with PVC may not be owing to segmental compatibility but simply good mutual adhesion between similar polar materials. There is no interaction or adhesion between CPE and polystyrene as would be expected. CPE addition to blends is accompanied by a decrease in component domain size. The relationship between CPE structure and its effectiveness as a blend modifier is discussed.
Flow properties of poly (vinyl chloride)
Authors: Hwo Chiu‐Hsiung , Johnson Julian F. 
Published: December 2004

AbstractA detailed review of the material published to date on the flow properties of poly(vinyl chloride) is given. The dependence of viscosity on concentration molecular weight, molecular weight distribution, shear and temperature for concentrated and molten poly (vinyl chloride) is considered. Polymer blends and plastisols are also included.
Rate of strain effect on the thermal conductivity of a polymer liquid
Authors: Cocci A. A. , Picot J. J. C. 
Published: December 2004

AbstractThe effective thermal conductivity of a polymer liquid was measured as a function of strain rate. The polymer liquids studied were three commercial grades of polydimethylsiloxane. The experimental results show a dependence of effective thermal conductivity on strain rate. This dependence is believed due to either the rotation of large clusters of entangled macromolecules, or the orientation of the individual macromolecules, or possibly the combination of both mechanisms simultaneously in shear flow.The effective thermal conductivity, for all three samples studied, increased with increasing strain rate. The rate of increase was found to decrease with increasing temperature.The thermal conductivity measurements were made in an annular axial flow test cell that utilizes a hot wire probe technique. Convection problems were eliminated by proper placement of the temperature measuring section of the wire in the cell.A tentative model was used through which the size of the cluster can be estimated. Once the size of the cluster is obtained, the rotational contribution to the energy transport can be estimated. Initial predictions agree well with the observed phenomena.
A mathematical model for predicting dynamic behavior of a plasticating extruder
Authors: Reber Dean H. , Lynn R. Emerson , Freeh Edward J. 
Published: December 2004

AbstractA mathematical model was developed to predict the dynamic behavior of flowrate and melt temperature in a plasticating extruder caused by changes in operating variables such as screw speed, back pressure and barrel temperature. The model has application for on‐line computer control of an extrusion process or for simulation purposes off‐line. Experimental data for developing the model was obtained from a 2½ in. diameter plasticating extruder producing high impact polystyrene sheet.
Dynamic modulus and damping in graphite composites
Authors: Fourney W. L. , Poesch J. G. 
Published: December 2004

AbstractBars made from graphite reinforced resin were impact loaded and foil strain gages were used to determine the characteristics of the stress wave as it propagated along the length of the specimen. Assuming one dimensional wave theory to be valid, values for the dynamic moduli were determined and these were compared to static values obtained from beam in bending tests for the same bars. The amount of damping of the graphite composites was also determined.
Effect of fiber‐matrix adhesion on the properties of short fiber reinforced ABS
Authors: Speri William M. , Jenkins Charles F. 
Published: December 2004

AbstractThe tensile strength, fracture energy, and impact strength of ABS reinforced with discontinuous crystalline fibers such as FybexDu Pont trademark.
can be controlled by manipulating fiber‐matrix interfacial adhesion. In “good bonding” situations composite tensile strength, thermal expansion coefficient, and elastic moduli are significantly improved over the unfilled resin. The excellent impact strength of unreinforced ABS can be retained by lowering the fiber‐matrix interfacial adhesion. This results in a corresponding reduction in the improvements in tensile and flexural strength. However, the elastic moduli and thermal expansion coefficients are relatively insensitive to changes in adhesion. Consequently, a material with high modulus (>500,000 psi), high Izod impact resistance (7.0 ft‐lb/in.), and low expansion coefficient (3.0 × 10−5 in./in./°F) can be obtained. A material with this unique combination of properties should find use in large parts such as camper tops, truck grilles, and snowmobile bodies.Fiber‐matrix adhesion was measured directly by an x‐ray analysis technique which could be employed because of the fiber's crystallinity and unique growth habit. This independent measurement allowed a correlation between bonding and composite properties. The interfacial bond strength was manipulated by a variety of fiber coatings and resin additions.
Time‐temperature superposition in two‐phase polyblends
Authors: Kaplan D. , Tschoegl N. W. 
Published: December 2004

AbstractThe temperature dependence of the mechanical properties of a 50/50 blend of PVAC and lightly crosslinked PMMA has been examined using the data of Kawai et al. The shift distances, log aT, were generated by bringing the experimental data into coincidence on master curves calculated from a Takayanagi model whose parameters were varied in different regions of temperature. This method allows one to construct a master curve for a thermorheologically complex two‐phase material if the model and the mechanical properties of the constituent phases and their temperature dependence is known. The shift distances then provide insight into the intricate relations between the time and temperature dependence of the mechanical properties of the composite.
Capillary rheometry of raw elastomers, butadiene‐acrylonitrile copolymers
Authors: Nakajima Nobuyuki , Collins Edward A. 
Published: December 2004

AbstractCapillary rheometry of four butadiene‐acrylonitrile copolymer raw elastomers was performed at 125°C over a wide shear rate range. The data were corrected for the effect of pressure on viscosity, for pressure loss in the barrel and at the capillary entrance, for the non‐Newtonian velocity profile (Rabinowitsch correction) and for the temperature rise at high shear rates (shear heating). The corrected results were compared to the tensile stress strain data obtained at comparable strain rates. The agreement between the capillary flow data and the tensile stress strain data was quite good, however, some slight systematic differences were noted. The difference was interpreted as the consequence of slipping of materials at the capillary wall. Die swell values were measured and presented as functions of shear rate and capillary length. Extrudate distortions are described.