bluuebunny/crossref_metadata_2025 huggingface dataset:
Heat transfer to molten polymers
Authors: Griffin O. M.
Published: December 2004

The 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

This 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.
Analysis of thermoplastic cup drawing
Authors: Warshavsky M.
Published: December 2004

The cup drawing process of thermoplastic sheet is analyzed on the basis of small deformation theory. The drawability of thermoplastic sheets is related to material parameters which may be investigated without performing an actual drawing process. Values for the drawability which are obtained by this method agree with values which are obtained by the Swift cup test.
The effect of molecular weight distribution on polyethylene film properties
Authors: Perron Peter J. , Lederman Peter B.
Published: December 2004

Polymer 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

Energy 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

Creep 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

Fracture 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

Nylon 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

Filling 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

Using 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

An 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

A 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

Blow 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.
The application of melt elasticity to polymer processing
Authors: Maxwell Bryce
Published: December 2004

The present state of knowledge of polymer melt elasticity is reviewed together with consideration of the problems that elastic effects cause in polymer processing systems. Two examples of the useful application of melt elasticity are presented, one in melt extrusion the other in polymer melt mixing.
Impact reinforcement of poly(vinyl chloride)
Authors: Petrich Robert P.
Published: December 2004

Several 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

A 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

Previous 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

A 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

The 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

A 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

Bars 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

The tensile strength, fracture energy, and impact strength of ABS reinforced with discontinuous crystalline fibers such as Fybex

Du 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

The 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

Capillary 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.
Structural relationship between thermomechanical history and strength of polymeric solids
Authors: Matsuoka S.
Published: December 2004

Ultimate 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.
The weathering degradation of polyolefins
Authors: Baum Bernard
Published: December 2004

The mechanism of weathering degradation of polyolefins is discussed. Variations in spectral radiation, temperature, density, polymer absorption spectra, orientation, and sample thickness are related to property deterioration. Organic ultraviolet stabilizers, zinc oxide stabilization, and UV catalyzed degradation are briefly reviewed.
Thermoset characterization for moldability analysis
Authors: Kamal Musa R.
Published: December 2004

The 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

The 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

Amorphous 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

Two 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

Results 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

A 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

The 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

In 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

The 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

Polymer 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

The 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

Polymer 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

Electron 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

The 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

Processors 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

Ternary 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

The 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

Computer 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

A 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

Liquid 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

A 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.