bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural relationship between thermomechanical history and strength of polymeric solids
Authors: Matsuoka S. 
Published: December 2004

AbstractUltimate properties in polymeric solids strongly depend on thermomechanical history. We have shown that the polymer structure which depends on thermomechanical history can be quantitatively described by the relative amounts of enthalpy and entropy. The excess enthalpy decreases upon annealing and increases under the tensile stress. The increase in excess enthalpy reduces the relaxation time; thus a local brittle‐to‐ductile transition may be induced by stress concentration. It follows that in a well‐annealed material, this transition is more difficult to induce. Effects of molecular weight and orientation are also discussed in terms of dissipation of strain energy as the condition required for the strength of polymeric solids.
Thermoset characterization for moldability analysis
Authors: Kamal Musa R. 
Published: December 2004

AbstractThe injection molding of thermosetting compounds involves complex interactions between material parameters and molding conditions, on one hand, and moldability and the ultimate properties of molded parts, on the other hand. The main role of the molding variables may be related to their effects on the cure time and temperature and on the flow and thermal phenomena that affect orientation and residual stresses. These effects are manifested in the ultimate mechanical properties and shrinkage of the molded articles. Only scattered empirical data are available on the effects of material parameters, like the basic kinetic, thermal, rheological, and pressure‐volume‐temperature properties of thermosetting compounds. The lack of useful information in this area may be related to the unavailability of sufficient, satisfactory data on the above properties. This situation has also resulted in limitations on meaningful work towards the mathematical modelling of the molding process, which would be useful for the optimization of production rates and product quality. The paper summarizes the status of work in this area with emphasis on recent results relating to kinetic, thermal, and rheological characterization of thermosetting molding compounds.
Cold rolling of polymers 2. Toughness enhancement in amorphous polycarbonates
Authors: Broutman Lawrence J. , Krishnakumar Suppayan M. 
Published: December 2004

AbstractThe effect of cold rolling on the Izod impact strength of amorphous polycarbonates has been studied. The impact strength is a function of the roll reduction as well as the original sheet thickness. Sheets varying from 0.125 to 0.645 inches in thickness have been studied and roll reductions up to 50 percent have been utilized. It is shown that enhancement in impact strength occurs at very small percent roll reductions. The orientation release stress has been measured as a function of roll reduction and the internal stresses through the thickness of the sheets have been studied by birefringence methods. It is suggested that the residual stresses are responsible for impact enhancement rather than the molecular orientation.
Cold rolling of polymers 3. Properties of rolled crystallized polycarbonates
Authors: Kobayashi Takao , Broutman Lawrence J. 
Published: December 2004

AbstractAmorphous polycarbonate sheets up to 1/4 inch in thickness have been crystallized both thermally and by acetone vapor sorption. For thick sheets acetone vapor sorption is the superior technique and a method has been developed for assuring homogeneous crystallized sheets. The crystallized polycarbonate can be cold rolled providing there is a residual acetone content to act as a plasticizer for the sheet. The tensile stress strain characteristics of the as‐crystallized sheets as well as the rolled crystallized sheets have been determined as a function of the residual acetone content. It is shown that a crystallized polycarbonate whose thickness is reduced by 74 percent can achieve a true stress at fracture of 27,180 psi and a strain of 33 percent. These values are significantly greater than the values obtained for rolled amorphous polycarbonates.
Prediction of diallyl phthalate molding performance from laboratory tests II. Comparison of mechanical spectrometer and brabender torque rheometer
Authors: Willard Paul E. 
Published: December 2004

AbstractTwo series of glass‐reinforced diallyl phthalate molding compounds from two different manufacturers were evaluated using a Rheometrics, Inc. Mechanical Spectrometer and a Brabender Torque Rheometer. Comparison of reactivity and minimum viscosity as measured by these two instruments is presented. The Mechanical Spectrometer appears capable of differentiating smaller changes in melt viscosity than does the Brabender Torque Rheometer.
Friction and friction‐generated temperature at a polymer‐metal interface
Authors: Price Howard L. , Burks Harold D. 
Published: December 2004

AbstractResults are presented of friction and thermal tests of molded polyimide and pyrrone polymers. The coefficient of sliding friction up to surface velocities of 2 m/sec (394 ft/min) and the coefficient of thermal expansion from 300 to 500°K (80 to 440°F) were measured. An apparatus was constructed to measure simultaneously the coefficient of sliding friction and the friction‐generated temperature. Measurements were made at a nominal pressure‐velocity product of 0.25 MN/msec (7100 lb/in.2 × ft/min) and at temperatures between 300 and 500°K (80 and 440°F).
Emulsion polymerization of vinyl chloride: A new method for particle size analysis of latexes of PVC and applications
Authors: Fischer N. 
Published: December 2004

AbstractA new particle size analysis of latexes has been developed using a disc centrifuge allowing a very fast zonal sedimentation of particles followed by an automatic optical device. This method, which involves 5‐10 minutes, permits the routine control of fabrication for emulsions of PVC. Linked to a computer, it permits accurate determinations of particle sizes in terms of weight, surface or number averages. The complete operation for one latex requires less than 15 minutes. This technique has been used to follow the growth of particles in seeding operations, i.e., monosized seed latex and the competitive growth of 2 populations of seed particles. Some results have also been obtained by comparing accurate particle size analyses of latexes with rheological properties of plastisols obtained from these latexes.
A dynamical theory of elastic micro‐dielectric polymers
Authors: Shahinpoor M. , Kalhor H. 
Published: December 2004

AbstractThe general incompatibility and microheterogeneity of polymeric mixtures are discussed. The concepts are extended to elastic polyblends whose polymer constituents are polarizable, non‐conducting and non‐magnetic. A theory is then developed for the interactions of dynamic deformation fields in polyblends with applied electromagnetic fields. It is shown that certain electro‐ and magneto‐acoustical and optical effects are the outcome of the above‐mentioned interactions. Plane elastic as well as electromagnetic waves are shown to be generally dispersive in such media. We have employed an internal scale parameter, commonly called the couple stresses constant, which can be estimated by measuring the speeds of plane waves, thus enabling polymer engineers and scientists to evaluate incompatibility in elastic polyblends. The present work also establishes a generalized Faraday effect by showing that there exist three pairs of left and right circularly polarized plane waves traveling at different speeds in a polyblend. We also discuss a new phenomenon, i.e. “micromagneto‐elastic dragging”, emerging from our analysis. This phenomenon asserts that the more profound the internal incompatibility of polyblends, the more depressed the speed of plane waves below their normal values observed in the absence of incompatibility. For convenience, we have called such materials elastic micro‐dielectric polymers or, in short, EMDP.
Variable development response of resists using electron beam lithography: Methods and applications
Authors: Henderson R. C. , Pease R. F. W. 
Published: December 2004

AbstractIn the manufacture of electronic devices for integrated circuits, reducing the number of resist steps is desirable for a variety of reasons. We describe some experiments on a process aimed at reducing the number of resist and registration steps in electron beam lithography. The process involves locally varying the electron dose in an electron sensitive resist (in this case poly[methyl methacrylate]) so that the different levels of exposure can be distinguished by subsequent developing. Reliable results have been achieved with three levels:

Strongly exposed (resist removed after short immersion in developer).
Partially exposed or “metastable” (resist removed only after prolonged immersion in developer).
Unexposed.
In strongly exposed regions, operations such as etching may take place while using the metastable and unexposed regions to protect the workpiece. Subsequently, the metastable region may be developed for further processing.
A comparison between simple shear, elongation, and equal biaxial extension deformations
Authors: Cogswell F. N. , Moore D. R. 
Published: December 2004

AbstractThe rheology of a high molecular weight polyisobutylene “Vistanex” L‐80 is measured at 20°C under constant stress creep loading in simple shear and simple elongation and compared with published data for biaxial extension. These data can be reduced to a single curve by the application of simple geometric parameters and instability during extensional flows may be interpreted on the basis of the Considère construction. The results are further extended by dynamic measurements to estimate the viscoelastic response of this material over a time scale of nine orders of magnitude. The rheological response shows an approximately linear relationship with stress up to elongation strains of 1.0, and, because of this, the results do not illuminate the present controversy over the selection of different equations of state to represent non‐linear polymer melt flow. However, this body of data, which the authors believe to be the most comprehensive presently available in terms of strain level and deformation geometry, does demonstrate that a viscoelastic polymer can respond to different deformation geometries in a simple manner.
Thermodynamics of dissipative materials with entropic elasticity
Authors: Astarita Gianni 
Published: December 2004

AbstractPolymer solutions and melts can both dissipate mechanical energy in flow, as well as accumulate elastic energy. If the assumption is made that elastic energy can be accumulated only through a decrease of conformational entropy, the general thermodynamic theory for non‐linear viscoelastic materials simplifies considerably. In particular, though no generality is lost as far as the constitutive equation for stress is concerned, the energy equation, which allows in principle a calculation of temperature distributions arising from frictional heating and heat removal, reduces to the usual form which is valid for viscous materials.
Predicting radiant energy transmission through polymer sheets
Authors: Progelhof R. C. , Throne J. L. 
Published: December 2004

AbstractThe flux models can be used to accurately predict the transmission or absorption of radiant energy through an absorbing scattering plastic. The apparent absorbing and scattering coefficients are dependent upon the physical characteristics of the body and the incident radiation as well as the actual absorption and scattering coefficients of the material. The apparent interfacial reflectivity can be estimated from the degree of scattering within the material.
Heat distortion and mechanical properties of polymers by thermal‐mechanical analysis
Authors: Riga Alan T. 
Published: December 2004

AbstractPolymer properties were measured as a function of temperature at 5 and 10°C per minute heating rates and as a function of time at constant temperature, using the Du Pont 940 thermal‐mechanical analyzer. Data are reported on deflection temperature under load, vicat softening temperature, and creep properties. These results have been correlated with ASTM values. These tests require short times and are applicable to thermoplastics, thermosets, and elastomers.
The role of crystallite dimensions in mechanical and diffusion characteristics of uniaxially oriented polymers
Authors: Prevorsek D. C. , Sharma R. K. 
Published: December 2004

AbstractElectron microscopy studies indicate that the microfibrils are a well defined element of many uniaxially oriented polymers. On the basis of these results it was inferred that the mechanical responses of uniaxially oriented polymers are similar to those of a parallel ensemble of the microfibrils. An important consequence of this microfibrillar model is that the type of load transfer is independent of crystallite aspect (length/diameter) ratio. The analysis of anisotropy in modulus of uniaxially oriented nylon 6, however, indicates that the load transfer characteristics of these polymers are dependent on crystallite dimension. A series response is observed only with fibers or films of low and intermediate draw ratio. Highly oriented structures, however, exhibit a nearly isotropic response in load transfer. These results show that uniaxial polymers must be analyzed in terms of a model where the crystallites are embedded in an “amorphous” matrix. The equations are derived for modulus, strength, and coefficient of diffusion in terms of crystallite dimensions, and the results compared with the experimental data.
The influence of additives on the flow behavior of ABS
Authors: Blyler L. L. 
Published: December 2004

AbstractThe flow and processing behavior of commercial plastics is determined not only by the characteristics of the base resin but also by the presence of additives of various kinds. In this study the influence of a number of additives on the rheological behavior of molten ABS was investigated using a capillary extrusion rheometer and a Weissenberg rheogoniometer. The additives studied included molding lubricants, rubber impact modifiers, flame‐retardant additives, and residual unreacted components remaining from the polymerization process. The mechanisms by which these species affect flow characteristics are described.
Thermoforming conditions in transparent/opaque coextruded sheet
Authors: Progelhof Richard C. , Throne James L. 
Published: December 2004

AbstractProcessors have encountered processing problems in dealing with thermoforming co‐extruded sheet where one layer is semitransparent to incident radiant energy of the heater banks and the other is opaque. An analysis of the radiant heating process shows that significant volumetric absorption of radiant energy takes place within the semitransparent sheet. From the model, it is shown that to minimize temperature excursions within laminated sheets (and thus reduce the tendency for delamination and blistering), heater banks should be programmed to cycle in an on‐off mode with a rather short cycle period.
The 1974 SPE polyolefin division award address: Phase behavior of polybutene‐1 plus polystyrene in carbon tetrachloride
Authors: Clampitt Bert H. 
Published: December 2004

AbstractTernary phase diagram for several polybutene‐1 and polystyrene resins in carbon tetrachloride have been determined. These show:

Almost the entire phase diagram is a two‐phase region.
The composition of each phase is mainly of one polymer type.
Increasing the molecular weight of either polymer diminishes compatibility.
To our knowledge, this is the first example of phase separation in common solvent polymer solutions that involves a poly α‐olefin. Viscosity and surface tension data on the equilibrium phases indicate the phases have the same surface tensions but far different viscosities. The upper phase is mainly polybutene‐1 and is much more viscous than the lower phase which is mainly polystyrene. Slight agitation of the phases gives an “emulsion” that may be cast into a polymer film. The film has a continuous phase of Form III polybutene‐1 and a dispersed phase of polystyrene. The polystyrene may be extracted from the film by immersion in methyl ethyl ketone to give a porous polybutene‐1 film.
Effects of a fluid environment on the stiffness of polymers
Authors: McCammond D. , Ward C. A. 
Published: December 2004

AbstractThe effects of an isopropanol environment on the deformation characteristics of copoly (acrylonitrile‐butadiene‐styrene) (ABS) and poly (vinyl chloride) (PVC) have been investigated. Creep tests were performed in tension and torsion both in air and in isopropanol. It was noted that accelerated rates of creep were encountered during the tensile tests in isopropanol as compared with air but no differences were noted during the torsion tests. An explanation is proposed that the greatly increased creep strains encountered in tension result from diffusion of the fluid into the polymer. The rate of diffusion is controlled by changes in the free volume which occur on application of uniaxial tensile stresses. The existence of the fluid molecules in the polymer matrix reduce its local creep resistance and produce swelling, both of which are manifested as increased creep strains. The fact that no effects were noted during torsion tests (where the free volume remains constant) or when an unstressed specimen was immersed in the fluid indicates that no significant absorption occurs at the equilibrium (unstressed) free volume.
Extruder scale‐up by computer
Authors: Maddock Bruce H. 
Published: December 2004

AbstractComputer simulation technology is used to define the problems in scale‐up of extruders from 2.5 to 3.5, 4.5, 6.0, and 8.0 inches in diameter. It is shown that the conventional practice of scaling‐up channel depths by the square root of the diameter ratio does not take full advantage of the potential output capacity of larger extruders and a faster rate of channel depth increase is proposed. It is also shown that inherent limitations resulting from decreasing barrel surface area and increasing flight clearance with increasing screw diameter will always result in a higher discharge temperature from the larger machine at any practical output rate. Frictional heat generation and heat removal requirements increase with increasing diameter, regardless of the scale‐up system used, and these limit the output capability of the larger sizes at low discharge temperatures.
Prediction of melt elasticity from viscosity data
Authors: Abdel‐Khalik S. I. , Hassager Ole , Bird R. Byron 
Published: December 2004

AbstractA simple method for predicting the primary normal stress function, θ, from viscosity data is proposed. A relation between θ and the viscosity function, θ, based on the Goddard‐Miller rheological equation of state, is given. An easy‐to‐use generalized chart for estimating θ from θ is presented; in order to use this chart, viscosity data must be available from the zero‐shear‐rate value of the “power law region.” The method was applied to six polymer melts, three polymer solutions, and an aluminum soap solution for which θ had been measured experimentally. Even though θ varied by a factor of 103 over the examined range of shear rate, the theory and experiment seldom differed by more than a factor of 2. The generalized chart for θ was combined with Tanner's theory to prepare a graph which may be used to estimate jet swell from viscosity data. Comparison with experimental data of jet swell for 4 polymer melts shows good agreement.
Effect of polymeric structure on the permeation rate in standard reference material sulfur dioxide permeation tubes
Authors: Reneker D. H. , Martin G. M. , Rubin R. J. , Colson J. P. 
Published: December 2004

AbstractLiquid SO2 sealed into tubes made of a fluorocarbon copolymer permeates the walls of the tube at a temperature‐dependent but accurately reproducible rate. Sulfur dioxide dispensers made in this way are called permeation tubes and are useful for calibrating instruments that measure SO2 concentrations in air. The National Bureau of Standards calibrates SO2 permeation tubes and makes them available as Standard Reference Materials. The permeation rate in a batch of nominally identical tubes varies enough that each Standard Reference Material tube must be individually calibrated. Changes in the length or radial dimensions of the tubes are much too small to explain most of this variation. An excellent (negative) correlation is found between the measured permeation rate and the density of the polymer (or weight per unit length). Since both the measured density and the permeation rate for this semi‐crystalline polymer depend upon morphological factors, but in different ways, x‐ray diffraction measurements of the thickness and orientation of the lamellar crystals were made and a mathematical model was set up to identify the morphological factors which can cause variations in the permeation rate.
Biaxial stretching of heat‐softened plastic sheets: Experiments and results
Authors: Schmidt Lawrence R. , Carley James F. 
Published: December 2004

AbstractA second‐generation apparatus was built and used to inflate heat‐softened plastic sheets to shapes from hemispheres to large spheroidal bubbles. Three sheet materials, polystyrene, high‐impact polystyrene, and cellulose acetate butyrate, were successfully formed beyond the hemispherical shape at temperatures somewhat below industrial levels. Four others, rigid poly‐(vinyl chloride), an acrylic‐modified PVC, cast poly(methyl methacrylate), and polycarbonate, could not be deformed beyond the hemispherical shape without rupture. Measurements included bubble profiles, thickness distributions and local extension ratios for the final bubbles; two plots of profile growth measured from high‐speed motion pictures; and a continuous record of bubble temperatures and blowing pressure from which the meridional temperature distributions were plotted.Fifteen bubbles were measured and analyzed. Profiles and extension ratios were compared with those computed from the equations of isotropic, isothermal elasticity, using several different strain‐energy functions with constant material parameters. Agreement over all fifteen bubbles on all properties was about ±10.8 percent (absolute) for the best models considered. Bubble growth occurred over periods of 5 to 8 seconds, with about 90 percent of the final area of the larger bubbles being generated in the final 1.5 seconds. The maximum areal elongations obtained were 18,600 percent for clear polystyrene at 238°F, 14,300 percent for high‐impact polystyrene at 224°F, and 1,010 percent for cellulose acetate butyrate at 280°F.
Properties of polypropylene‐polyethylene blends
Authors: Noel Oscar F. , Carley James F. 
Published: December 2004

AbstractHigh‐density polyethylene (PE) and isotactic polypropylene (PP) were melt‐blended in the following percentages of PE by weight: O, 10, 33.3, 40, 50, 66.6, 90, and 100. For these blends we obtained data on shear stress vs shear rate; tensile modulus and strength; density; and rates of water‐vapor transmission for films. The shear‐rate/shear‐stress data at 190 and 210°C are well fitted by the Ellis model with a maximum relative error of 5 percent. At 190°C all the mixtures were found to exhibit flow instabilities at high shear rates except the 90 percent and pure PE compositions. These, however, were unstable at 140, 150, and 160°C.The 10, 33.3, 40, 50, and 66.6 percent PE mixtures ruptured at elongations of less than 15 percent at the maximum tensile stress. The maximum tensile strength and modulus pass through maxima at 10 percent PE. Density is given by the equation ρ = 0.9029 + 0.0544 (wt fraction PE). Water‐vapor permeability was measured using wax‐sealed permeability cups, according to ASTM E96‐66. Valid results were obtained for only a few compositions because of faulty seals that could be detected only during careful dismantling of the specimen dishes. Faulty seals could account for the value, about ten times ours, reported in the literature for linear PE.