bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of optics and resists for 3000 Å wavelength photolithography with a Perkin‐Elmer printer
Authors: Shankoff T. A. , Bruning J. H. , Johnston R. L.
Published: December 2004

A Model 111 Perkin‐Elmer projection printer, with a 3100 Å exposure capability was evaluated for far‐UV printing. The improvement found in resolution at 3100 Å compared to 4000 Å was roughly proportional to the mean exposure wavelengths in the near and far‐UV as verified by electrical probe yield data of printed meander patterns. The processing latitude of various photoresists of the diazide type was found in the 1.0 μm and 2.5 μm line width range by electrically measuring the line widths of meanders etched into metal films using the appropriate resist mask. Exposures were varied continuously on individual wafers so that the resist linewidth change vs exposure could be determined using a minimum number of wafers. It was found that resists such as AZ‐2400 which pass much of the exposing radiation have better latitude than those that absorb most of the exposing radiation (HPR‐204, MPR). Some new, unconventional resists studied have even greater latitude than the diazide resists. Design compensations which have to be made for proximity and related effects at fine dimension are in the 0.1 μm to 0.2 μm range. Depth‐of‐focus for the printer studied seems to be adequate for careful work at 1.0 μm using 3100 A exposure. The overlay printing capability, which includes mask quality, operator error, and printer optics and stability, is within 0.25 μm from level‐to‐level.
Polydiallylorthophthalate resist for electron‐beam lithography
Authors: Yoneda Y. , Kitamura K. , Naito J. , Kitakohji T. , Okuyama H. , Murakawa K.
Published: December 2004

Polydiallylorthophthalate, PDOP, of low molecular weight and low molecular weight dispersivity has been prepared and investigated as a negative resist for electron‐beam, X‐ray and ultraviolet lithographies. The resist polymers were prepared by a conventional fractional precipitation method. It has been found that a high resolution pattern is obtained by using a molecular weight of 1 × 104 and an Mw/Mn < 2. This gives a good solubility difference between the exposed and unexposed portions in the developer. Resolution is less than 1 μm without any scum. Sensitivity for 15 kV electron bourns is 4 × 106C/cm2; and for X‐rays (Al Kα) it is 100 mJ/cm2. Sensitivity for UV is 10 times that of poly(methyl methacrylate), and resistance for C3F8 dry etching is comparable to AZ‐1350J.
Influence of the Braid on transition temperatures as obtained by torsional Braid analysis
Authors: Hedvat Schowl
Published: December 2004

Torsional Braid Analysis (TBA), like many other sample‐supported techniques, measures the transition temperatures of a polymer deposited on an elastic support. It is shown here that any polymer transition found by the location of the maximum in the log decrement Δ (or loss tangent tan δ) of a composite shifts to lower temperatures as the rigidity (or modulus) of the elastic support is increased. The magnitude of this temperature decrease is larger for transitions at which a composite has a larger support‐to‐polymer rigidity ratio. In general the above conclusions hold even with unsupported systems if the rigidity (or modulus) of the sample can be increased without interfering with the polymer domain under investigation, for example, by crosslinking one of two phases of microphase‐separated co‐polymers.
Experiments in extensive mixing in laminar flow. I. Simple illustrations
Authors: Ng Kwok Y. , Erwin Lewis
Published: December 2004

Simple quantitative mixing experiments in well‐defined deformations clearly demonstrate the validity of previously derived equations relating deformation and mixing. A simple mixture of black and white polyethylene is studied by direct measure of striation thickness. The well‐known linear relationship in simple shear is demonstrated. By using a simple method for uniform reorientation, the second power relationship in shear once interrupted, the third power relationship in shear twice interrupted and the fourth power relationship in shear interrupted three times are demonstrated. In uniaxial elongational mixing of a silicone fluid, exponential dependence of mixing on strain is demonstrated.
Viscosities of molten polymer blends
Authors: Carley James F. , Crossan Stephen C.
Published: December 2004

Pairs of four thermoplastic resins, polystyrene, poly(methyl methacrylate), acetal homopolymer, and nylon‐12, were intensively melt‐blended in nine proportions from 0 to 100 percent. Capillary rheometry at 210°C was done on each blend; melt densities were also measured on most of them. The dependence of shear stress on Rabinowitsch‐corrected shear rate was accurately represented, for all the blends, by a simple empirical model. The dependence of viscosity, at particular shear rates between 5 and 1000 s−1, on blend composition was examined and we fitted two viscosity‐composition models to all the systems by least‐squares procedures. The character of the dependence of blend viscosity on composition varied widely for the five binary systems studied, two being monotonic over the whole range of shear rate, two exhibiting clear minima and one displaying mixed behavior, with both a minimum and maximum viscosity seen at shear rates near 250 s−1. The McAl lister three‐body model satisfactorily describes the viscositycomposition dependence in all five systems. A simpler blend rule was useful only in the monotonic systems, and even there it was inferior to the McAllister model.
Flow of carbon black loaded styrene‐butadiene (SBR)‐cis‐polybutadiene blends through capillary dies—influence of mixing and the location of carbon black
Authors: Lee Biing‐Lin
Published: December 2004

The flow behavior of carbon black loaded styrene‐butadiene (SBR)‐cis‐polybutadiene (BR) is investigated as a function of mixing and the location of carbon black. The blends consist of an 80:20 weight ratio of SBR and BR with the incorporation of 20 phr carbon black via three different schemes to control the location of carbon black in the individual rubber phases. These are: (A) free black mixing of the three components, (B) mixing of SBR‐black masterbatch with BR, and (C) mixing of BR‐black masterbatch with SBR. Dynamic Mechanical Analysis (DMA) was used to characterize carbon black distribution. The damping characteristics indicate that when carbon black is masterbatched into either one of the rubbers, it continues to remain incorporated in that particular rubber phase upon blending with the second rubber. The flow behavior is measured with an Instron capillary rheometer. The results indicate that the viscosity function of these blends is not sensitive to the mixing conditions. However, the elasticity is always, dependent on mixing. Elasticity is expressed as ΔPe/σ, where ΔPe is the entrance pressure drop from the Bagley plot and σ the shear stress. In general, ΔPe/σ of the blend decreases with increasing mixing.
Crosslinking of hydroxyl‐terminated liquid rubber with divalent metal salts of mono(hydroxyethyl) phthalate, anhydrides, and bisepoxide
Authors: Matsuda Hideaki
Published: December 2004

Crosslinking of hydroxyl‐terminated liquid rubber with divalent metal salts of mono(hydroxyethyl) phthalate, anhydrides and bisepoxide was investigated by the diols‐anhydridesbisepoxide, reactions. As the anhydride, succinic anhydride and hexahydrophthalic anhydride were used, and bisphenol A diglycidyl ether was the bisepoxide used. The metal carboxylate groups of these metal salts catalyzed the crosslinking reactions and, further, the Mg salt showed higher catalytic activities than the Ca salt. As for the physical properties of the metal‐containing cured rubbers obtained, tensile strength and Shore A hardness increased with increase in the metal salt content. In addition, the rubbers containing Mg showed better physical properties than those containing Ca. Meanwhile, elongation showed a maximum with increase in the metal salt content. Resistance; to water and chemical attack, thermal behavior, and stress relaxation are also discussed.
Processing history in extrusion dies and its influence on the state of the polymer extrudate at the die exit
Authors: Winter Horst Henning , Fischer Ernst
Published: December 2004

A method is proposed to describe the processing history in extrusion dies and its influence on the state of the polymer after processing. The approach differs from conventional processing analysis, which uses the shear viscosity function to calculate pressure drop vs flow rate relations. The approach also differs from heuristic analysis which tries to find empirical correlations between rheological observations and processing behavior. The method is applied to the flow in annular extrusion dies. An integral constitutive equation is chosen to calculate the flow and to describe the flow history at the die exit as memorized. In the analysis, the kinematics are locally approximated by isothermal steady shear flow. The velocity and the velocity gradient are used to determine the Finger strain tensor, the path lines, and the residence times of the deforming material elements. Measures of the state of the polymer at the die exit are chosen to be the stress ratio N1/2τ12 and the free recovery. The free recovery calculations presume that the extrudate is chopped into small volumes of homogeneous flow history. The results of the calculations show the polymer very sensitively reacts to small changes of the die geometry. Important applications of this analysis are film blowing and blow molding, where the extensional behavior during the blowing process outside the die depends greatly on the preceding shaping process inside the die.
A study of the structural integrity of graphite composite structure subjected to low velocity impact
Authors: Dobyns A. L. , Porter T. R.
Published: December 2004

An analysis for the transient deflections, bending strains, and interlaminar shear stresses in a simply supported laminated composite plate subject to low velocity impact has been obtained using a series solution of the plate governing equations. Results are presented showing the effect of plate geometry and impact location on damage mode. Computed stresses and strain are compared with impact test data to verify, the analysis.
Similarity in orientation effects on thermal conductivity and flow birefringence for polymers—polydimethylsiloxane
Authors: Chitrangad B. , Picot J. J. C.
Published: December 2004

Experimental results on flow birefringence and thermal conductivity measured under shearing strain conditions for liquid polydimethylsiloxane are presented. Both phenomena show similar dependency on strain rate, and this dependency is attributed to net orientation of the macromolecules. An orientation model is presented and is shown to be qualitatively correct.
Rheological and mechanical properties of plasticized poly(vinyl chloride)
Authors: Tse Mun‐Fu
Published: December 2004

The dependence of rheological properties of a plasticized, filled poly(vinyl chloride) compound on three different methods of thermomechanical treatments has been studied. These three different states of the compound are the dry blend mixed at a maximum temperature of 93°C, the two‐roll milled sample prepared at 150°C from the dry blend and the molded sample pressed at 170°C from the previously milled material. At 150°C the viscosity and elasticity of the molded sample are considerably higher than those of the dry blend and the milled sample. At higher temperatures, although their flow curves more or less merge, extrudate swell, extrudate appearance and extrudate tensile properties of the three samples vary. The mechanical and Theological properties of the quenched and annealed molded samples and those of the same compound without filler have also been investigated.
Effect of compaction rate during the cold forming of polymeric powders
Authors: Crawford R. J.
Published: December 2004

During many plastics processing methods, both conventional and novel, plastic powders or granules are subjected to pressure. The pressure transmissibility through the powder has an important effect on the success and efficiency of the process, and so it is desirable to be able to predict the pressure at any point from a knowledge of the applied pressure and the geometry of the system. To examine this pressure transmissibility effect, poly(vinylidene chloride) powder has been compacted in a metal die under different rates using either load or displacement control. It has been found that rate effects are particularly important for loading rates greater than 8 MPa/s and displacement rates greater than 7.5 mm/s. The ratio of transmitted pressure (P2) to applied pressure (P1) has been measured for a range of compact geometries, and it has been found that the ratio is approximately constant during the latter stages of the compaction process. Various laws for predicting the transmitted pressure have been studied, but it has been found that the simplest equation that agrees with the data is of the form
The hydrostatic extrusion and die‐drawing of glass‐fiber‐reinforced polyoxymethylene
Authors: Hope P. S. , Richardson A. , Ward I. M.
Published: December 2004

The solid‐phase forming of glass‐fiber‐reinforced poly‐oxymethylene has been investigated using the techniques of hydrostatic extrusion and die‐drawing. Although considerable orientation of the glass fibers and the polymer matrix occurs in both processes, there are very appreciable differences between the stiffnesses of the glass‐filled products in the two cases. For hydrostatic extrusion, the moduli of the glass‐filled products are significantly higher than those of the unfilled products. In die‐drawing, however, the absence of hydrostatic pressure allows debonding of the fibers from the matrix to occur, accompanied by extensive void formation. The fibers are, consequently, no longer effective as a reinforcing phase, the moduli of the glass‐filled products being no higher than those of the unfilled products.
A proposed model for accelerated‐stress life‐test data exhibiting two failure modes
Authors: Derringer George C.
Published: December 2004

Accelerated‐stress life‐testing involves testing of a material or system at a series of stresses higher than that which is normally seen in service. An estimate of the service life is then obtained by extrapolating the failure time vs stress relationship to use stress. A common problem with this methodology is that a change in failure mechanism may occur if stresses become too high. When this occurs, the data above and below the failure mode transition point are generally treated separately. This paper discusses a model that allows for a change in failure mechanism and characterizes the transition by a probability density function over stress. Advantages of the model are: it allows representation of all test data by a single equation; it allows probability statements to be made about the probability of failure of either failure mode; it allows optimal experiments to be designed; and it allows data in the area of the failure mode transition to contribute to the precision of the estimated service life.
Experimental studies of phase separation in reaction injection‐molded (RIM) polyurethanes
Authors: Camargo R. E. , Macosko C. W. , Tirrell M. V. , Wellinghoff S. T.
Published: December 2004

A series of polyether polyol (polyoxypropylene capped with polyoxyethylene), 4‐4′ diphenylmethane diisocyanate, and 1,4 butane diol urethanes were prepared by reaction injection molding with different levels of catalyst (dibutyl tin dilaurate). The degree of phase separation, morphology, and molecular weight were compared by dynamic mechanical spectroscopy, wide‐angle x‐ray scattering, optical microscopy, and gel permeation chromatography. Slowly reacted (uncatalyzed) samples displayed better phase separation, crystallinity, low molecular weight, and poor mechanical properties. Fast‐polymerized (highly catalyzed) samples showed a high degree of phase intermixing, low crystallinity, high molecular weight, and good mechanical performance. Differences between these two behaviors are discussed with the aid of a simplified phase diagram. Slowly reacted samples phase‐separate through nucleation and growth of large spherulites, while quickly reacted samples form a much finer, interconnected microstructure. Infrared studies of phase separation for slow systems are presented and used to discuss phase separation in fast polymerizations.
Rigid polyurethane foams: A model of the foaming process
Authors: Rojas A. J. , Marciano J. H. , Williams R. J.
Published: December 2004

A model of the manufacture of rigid polyurethane foams by free rising is presented. The extent of cream and rise periods as well as the amount of blowing agent necessary to give the desired foam density are theoretically predicted. The rate of blowing agent evaporation is calculated from an experimental boiling temperature vs. composition curve. Experimental runs were carried out with a formulation consisting of a polymeric isocyanate, a polyether polyol based on sorbitol, a silicone‐polyol block‐copolymer as surfactant, dibutyltin dilaurate as catalyst, and trichlorofluoromethane as blowing agent. Mixing was performed in situ in the mold using a commercial foaming machine. Experimental results gave a satisfactory agreement with model predictions. A diagram containing all the relevant information may be theoretically built and used for the selection of adequate operating parameters for a given formulation.
Measurement of dielectric tan δ during deformation of a polyurethane elastomer
Authors: Venkataswamy K. , Ard K. , Beatty C. L.
Published: December 2004

Dielectric measurements were carried out during deformation of a polyurethane elastomer. Dielectric tan δ was used to monitor deformation during and after stress relaxation experiments. The polyurethane elastomer exhibited multiple dielectric relaxation behavior: an α peak associated with the glass transition and a β peak attributed to the local motions of the groups in the main chain or pendant to it. At high stress levels, both α and β peaks are shifted to higher temperatures, resulting in higher activation energies. These results can be interpreted in terms of increasing chain orientation and the resultant changes in the local environments of chain segments during deformation.
Moisture absorption by tetraglycidyl 4,4′ ‐diaminodiphenyl methane/4,4′‐diaminodiphenl sulfone epoxies containing brominated epoxy copolymers
Authors: Goobich J. , Marom G.
Published: December 2004

The effect on moisture absorption of introducing bromine into epoxy resins is investigated. The research is carried out with a tetraglycidyl 4,4′‐diaminodiphenyl methane/4,4′‐diaminodiphenyl sulfone system, and compared with a reference system of diglycidyl ether of bisphenol A/diaminodiphenyl methane epoxy, both systems containing brominated reactive epoxy additives. The results indicate that the presence of bromine reduces drastically the rate and the maximum level of moisture absorption. The presence of bromine is shown to have only a small effect on the high‐temperature properties and on the glass‐transition temperatures of the dry resins. Moreover, due to their lower moisture absorption capacity, the glass‐transition temperatures of the wet brominated resins are higher than the counterparts of the original bromine‐free epoxies.
Computer simulation of injection molding
Authors: Kamal Musa R. , Laflrur P. G.
Published: December 2004

The injection‐molding process consists of three consecutive stages: filling, packing, and cooling. In order to obtain some insight into the phenomena involved in the process, and particularly in order to evaluate the moldability of certain resins and to predict the microstructure and properties of products molded therefrom, a number of workers have employed a variety of techniques based on mathematical simulation of the process. Mathematical simulation involves writing the relevant continuity, momentum, and energy equations governing the system, with appropriate boundary and initial conditions representing the prevailing conditions in the cavity and delivery channels. In order to obtain meaningful solutions to the above equations, detailed information is required regarding the thermodynamic, thermal, and rheological properties of the resin. Moreover, the prediction of the microstructure and ultimate properties of the molded article requires a knowledge of the morphological, crystallization, and orientation phenomena that take place under the influence of the thermo‐mechanical history experienced by the resin. The complexity of the equations involved results in the utilization of a number of simplifying assumptions and the resort to computer simulation and numerical solutions of these equations. A variety of numerical schemes based on finite difference and finite element methods has been employed by various researchers.
Fracture toughness (KQ) testing with a mini‐compact tension (CT) specimen
Authors: Lee C. Y‐C. , Jones W. B.
Published: December 2004

A testing method using the Rheometrics Mechanical Spectrometer as the loading instrument to measure the fracture toughness KQ, which is related to a specific sample geometry and dimensions (half‐inch compact tension) is reported. The small sample size requirement makes it attractive to do fracture toughness testing on newly synthesized material for preliminary material study and comparison purposes. Commercially available epoxy resins were used to check the procedure at different temperatures (−150° to 250°C). An empirical crack length averaging method was used that appears to give constant KQ values independent of the a/W ratio values. The fracture surfaces were studied using scanning electron microscopy.
Effects of shearing conditions on crystalline orientation and relaxation in polyethylene
Authors: Hsiue E. S. , Robertson R. E. , Yeh G. S. Y.
Published: December 2004

The effects of shearing conditions (i.e., shear temperature and shear rate) on the degree of orientation of polyethylene (Marlex 6006) and to what extent the induced orientation could be relaxed were examined in this study. Two types of samples were prepared: namely, SIC (shear‐induced crystallization) and non‐SIC samples. The SIC samples show induction times and possess a high degree of c‐axis orientation along the shear direction. The induced orientation of SIC samples can be relaxed to a small extent but does not reach a steady value. Non‐SIC samples do not show induction times and they show low degrees of c‐axis orientation. The induced orientation of non‐SIC samples can be relaxed to a steady state value with an activation energy of 90 kJ/mole. Our results also indicate that, when the shear temperature is at and above 145°C, polyethylene can be sheared up to 200X without introducing any significant molecular orientation even at very high shear rates.
Modeling of transport of small molecules in polymer blends: Application of effective medium theory
Authors: Sax J. , Ottino J. M.
Published: December 2004

This article concerns itself with the prediction of effective diffusion coefficients of small permeants in binary polymer blends of varying degrees of miscibility and microstructural order. Several models have been critically evaluated with the help of previously published experimental data and in terms of consistency of morphological information provided by small permeants serving as morphological probes. Completely random, two‐phase media have been modeled in terms of Effective Medium Theory with the coordination number (z) describing the average morphology. A comprehensive analysis of experimental data has shown a correlation between z and various physical situations. Near the percolation threshold, z attains a maximum value while, above it, z tends to decrease with increasing content of the conductive component. Accurate predictions of effective diffusivity can be made for volume fractions between 0.3 and 0.8 by letting z = 6. Evidence for phase inversion was studied in terms of models with ordered microstructure and transport data.
Influence of external environments on fatigue crack growth in epoxy resin
Authors: Mizutani K. , Iwatsu T.
Published: December 2004

A fatigue crack propagation in an epoxy resin in the presence of organic solvents or water was studied from the viewpoint of fracture mechanics. The fatigue crack growth rate (da/dN) of the resin under various stress‐intensity‐factor ranges (ΔKl) was measured using a tapered double‐cantilever beam specimen. In air environment, plots of da/dN against ΔKl were found to be represented by the Paris equation: da/dN = C(ΔKl)n, where C and n are empirical constants. In this case, the constant n was about 6.5. The fatigue crack growth rate in the presence of organic solvents decreased to 1/10 ∼ 1/4 of that in air environment at the same ΔKl. It was considered that a penetration of the solvent molecules into the resin enlarged a region of plastic deformation near the crack tip. Therefore, more fracture energy was needed for the growth of the fatigue crack. Also, observations of the fatigue fracture surfaces suggested that a large plastic deformation occurred at the crack tip in the presence of solvents.
Residual stress craze and crack formation in poly(methyl methacrylate)
Authors: Bevan L. , Nugent H.
Published: December 2004

Samples of poly(methyl methacrylate) with a central circular hole are compressed, and crazes form on or after unloading, provided that the strain attains or exceeds a threshold value ϵt. Crazes induced in air are transformed rapidly to cracks, but environmental crazes are more stable. These residual stress crazes form at the diameter of the hole on a plane perpendicular to the applied stress direction. In contrast, during loading, crazes form on the vertical plane containing the hole axis. Unloading crazes are relatively insensitive to changes in strain rate, whereas loading erazes have a pronounced rate dependence. Environmental residual stress crazing exhibits an apparent rate sensitivity at constant time, but the critical applied strain ϵt is essentially constant, irrespective of rate, if the sample is in contact with the environment for a sufficiently long time to ensure that the minimum ϵt is obtained. Residual stress crazes appear to initiate at the equator of the hole, and the maximum tensile residual strain, indicated by a strain gauge, occurs in this position.
Structure‐properties relationships in biaxially oriented polypropylene films
Authors: De Vries Albert J.
Published: December 2004

A series of biaxially oriented polypropylene films has been extensively investigated with respect to structural characterization and with regard to various end‐use properties. The relationships between properties and structural characteristics such as crystallinity content and molecular orientation in crystalline and non‐crystalline phases were compared with similar relationships in uniaxially oriented polypropylene films. Notable differences between uni‐ and biaxially oriented films, in particular with regard to non‐linear mechanical behavior (tenacity, impact strength, tear strength) could be explained, at least partly, in terms of structural characteristics (molecular orientation and mobility) related to the non‐crystalline phase.
The length of a transfer unit (LTU) for polymer devolatilization processes in screw extruders
Authors: Collins G. P. , Denson C. D. , Astarita G.
Published: December 2004

In this paper we introduce the concept of the length of a transfer unit (LTU) for polymer devolatilization and show that the LTU is an appropriate measure of the effectiveness of the process unit in which the devolatilization operation is conducted. The utility of the concept is demonstrated for the case when the process unit is a twin screw extruder for which values of the LTU were determined from experimentally measured values of devolatilization rates. Values of the LTU were found to depend solely on the fluid mechanics in the extruder as expected and were in good agreement with the predictions of a theoretical expression developed for the system that was studied. Finally, we discuss the implications of the LTU concept in relation to the engineering design and analysis of polymer devolatilization processes.
Plane strain fracture toughness of polyethylene pipe materials
Authors: Mandell J. F. , Roberts D. R. , McGarry F. J.
Published: December 2004

The plane strain fracture toughness of medium density polyethylene pipe materials has been investigated over a range of test temperatures and rates. Conditions are defined under which valid fracture toughness values can be obtained; at higher temperatures the material is notch‐insensitive. Fracture surface morphology is described, and features are compared with predictions from the Dugdale model. The toughness derives from a band of fibrillar, drawn morphology associated with crack initiation or slow growth. The plane strain fracture toughness correlates with percent crystallinity according to the same relationship whether the crystallinity is varied by thermal treatment, comonomer content, or molecular weight.
Dynamic mechanical and thermomechanical properties of silicone‐polycarbonate block copolymers
Authors: Maung W. , Chua K. M. , Ng T. H. , Williams H. Leverne
Published: December 2004

Representative random, alternating block copolymers of polydimethylsiloxane (PDMS) and bisphenol‐A‐polycarbonate (BPAPC) were studied by thermomechanical and dynamic mechanical techniques. Data on glass transition temperatures (Tg), heat‐deflection temperatures (Td), Vicat softening temperatures (Ts), coefficients of linear expansion (α), stress‐strain, and stress relaxation for four PDMS‐BPAPC block co‐polymers are presented. The effect of casting films from mixed n‐hexane‐methylene chloride solution on the thermomechanical and dynamic mechanical properties was also studied.
Relationship between polymerization conditions and rheological properties for styrene‐acrylonitrile copolymers
Authors: García‐rejón A. , Rangel‐nafaile C. , Ríos L. , Cid F.
Published: December 2004

Styrene‐acrylonitrile (SAN) copolymers are widely used in industrial applications in the fields of appliances, automotive, housewares, medicine, and packaging. They possess most of the features of polystyrene, with improved resistance to chemical attack, stress eracking, and heat deflection, and with greater strength and toughness. Their properties depend on several factors, the most important being the composition of the feed (monomer ratio), the type and quantity of the initiator, and the solvent to monomer ratio in the feed. This work presents the results of a continuing program that studies the effect of the above‐mentioned polymerization variables on the viscoleastic properties, and the way in which these variables can be adjusted in order to obtain a SAN copolymer with specific properties.
Highly elastic‐constant vicosity fluids
Authors: Choplin L. , Carreau P. J. , Kadi A. Ait
Published: December 2004

The rheological properties of three types of fluids that exhibit large normal stresses are examined and compared. These fluids have a constant or nearly constant viscosity and can be used as model viscoelastic fluids, covering a range of viscosity from 0.1 to 124 Pa.s. One lubricant, Emkarox FC 31‐45000, is shown to have the characteristics of a second‐order fluid. Series difficulties encountered in measuring the rheological properties of the Separan—corn syrup solutions (Boger fluids) are reported. The Emkarox and solutions of polyacrylamide (Pusher 700) in mixtures of glycerine and water are proposed as better model fluids.
Effect of the addition of EPM copolymers on the properties of high density polyethylene/isotactic polypropylene blends: II. Morphology and mechanical properties of extruded samples
Authors: D'Orazio L. , Greco R. , Martuscelli E. , Ragosta G.
Published: December 2004

The influence of the addition of two ethylene‐propylene random copolymers (EPM) with different composition on the mechanical properties, thermal behavior and overall morphology of high density polyethylene (HDPE)/isotactic polypropylene (iPP) blends, was investigated on extruded samples. The experimental data showed that the morphology of binary HDPE/iPP blends is drastically modified by these additives and that the ultimate mechanical properties of these mixtures are greatly improved. A reasonable explanation of these results can be ascribed to the fact that these copolymers can act as “compatibilizing agents” in the amorphous regions of the two semicrystalline homopolymers. The extent of such effects is dependent on the chemical structure and/or on the molecular mass of the added copolymer as well as on the HDPE/iPP blend compositions.
Characterization of electron beam crosslinked poly(styrene‐block‐ethylene‐co‐butylene‐block‐styrene)
Authors: Zurawski D. E. , Sperling L. H.
Published: December 2004

A saturated triblock copolymer, poly(styrene‐block‐ethylene‐co‐butylene‐block‐styrene) was chemically crosslinked using trimethylol propane trimethacrylate, TMPTM, and subjected to electron beam radiation. The gel percent, Gehman ten second modulus, and stress relaxation were measured to characterize the materials as a function of crosslinker concentration and radiation level. A time‐temperature super‐position master curve was generated at 63°C for 3 percent TMPTM and 5 Mrads of radiation, which indicated rubbery plateau behavior at long times of measurement, as opposed to the uncrosslinked material, which continued to creep and flow. The main locus of crosslinking was within the polystyrene phase, which explains reduced creep and stress relaxation only for long times of measurement and/or high temperatures. Based on shifts of the glass transition temperatures, it was estimated that 11 to 16 percent poly(ethylene‐co‐butylene) was dissolved in the polystyrene phase.
The stability of blends of incompatible thermoplastics
Authors: Maxwell Bryce , Jasso Guillermo L.
Published: December 2004

Conventional thermodynamic reasoning would predict that it would be very difficult to melt blend incompatible polymers and that if such blends were made they would be highly unstable and would phase separate upon heating. A method has been developed to melt blend incompatible polymers (such as poly(methylmethacrylate) and polyethylene) to form two continuous interpenetrating phases and that upon prolonged heating the stability of the structure is increased rather than decreased.
Mechanical properties of injection molded blends of poly(ethylene‐terephthalate) and poly(amide‐6,6)
Authors: Kamal M. R. , Sahto M. A. , Utracki L. A.
Published: December 2004

Data have been obtained regarding the tensile and impact behavior of pure poly(ethylene terephthalate) (PET) and polyamide 6,6 (PA) and blends of PA in PET in concentrations of 5, 10, 25, 30 and 35 percent by weight of PA. The measurements were carried out at −40, 23 and 70°C. Dispersion and sample preparation were carried out in a reciprocating screw injection‐molding machine. All blends exhibited brittle behavior and low strength, when compared to pure components. Although some enhancement of mechanical properties might be realized by orientation, it is suggested that the observed behavior might be attributed to the low quality of dispersion achievable in injection molding process. This conclusion is supported by microscopic evidence.
Hydrogen bonding in polymer systems
Authors: Cangelosi F. , Shaw M. T.
Published: December 2004

The importance of hydrogen bonding interactions in promoting polymer miscibility has been the subject of much recent investigation. In this study, we address the question of the effect of molecular size and geometry on the intensity of the hydrogen bonding interaction. To this end, the interaction of the functional group in various molecules with a variety of acid and base polymer matrices has been monitored using infrared spectroscopy. The “probes” used in this study each contained only one functional group per molecule to prevent intra‐molecular association. The probes were acetone, di‐n‐hexyl ketone, 10‐nonadecanone, cyclohexanone, cyclododecanone, isopropanol, 4‐decanol, 10‐nonadecanol, cyclohexanol, and cyclododecanol. The interactions of the base probes with poly‐(vinyl chloride), poly(vinylidine fluoride), phenoxy, poly(styrene‐co‐allyl alcohol), and a variety of cellulosic polymers were studied. Acid probe interactions were measured in poly(pivalolactone), poly(butanediol‐1,4‐terephthalate), poly‐(acetal), poly(ϵ‐caprolactone), poly(vinyl methyl ether), poly(4‐methoxy styrene) and poly(ethylene oxide). The effect of the presumably inert poly(styrene) and ethylene‐propylene rubber matrices on the probe's functional group was studied for comparison.
A comparison of miscible binary blend interaction parameters measured by different methods
Authors: Harris J. E. , Paul D. R. , Barlow J. W.
Published: December 2004

Miscible blends of the polyhydroxy ether of bisphenol‐A, Phenoxy, with a series of aliphatic polyesters were studied using melting point depression analysis and sorption to obtain the Flory‐Huggins polymer‐polymer interaction parameter, B. The B values obtained from these measurements were found to agree well in sign, magnitude, and variation with ester repeat structure and to also agree well with B values measured calorimetrically for mixtures of low molecular weight compounds with structures which are analogous to those of the polymers. These comparisons suggest that the same mechanisms are responsible for the exothermic heats of mixing measured directly for the analog compounds and indirectly for the miscible polymer blends. For this general system, evidence is provided which suggests that hydrogen bond formation between the hydroxyl group on Phenoxy and the ester moiety is probably responsible for the exothermic interactions and polymer blend miscibility observed.
Review on processing ultra high tenacity fibers from flexible polymer
Authors: Ohta T.
Published: December 2004

The various efforts up to date on the processing of ultra high tenacity fibers from flexible polymer have been summarized in this report. Some significant parameters correlating well with ultra high tenacity have been found through consideration of experimental results of polyethylene, despite the wide diversity in the processing techniques, degrees of drawing, thermal conditions, and molecular weight characteristics. It has been concluded from those parameters that ultra high tenacity fibers can be only attained by processing techniques satisfying the following structural principles simultaneously:

ultra drawing with draw ratio above 20 for increasing the number of tie molecules and the degree of molecular orientation.

reduction of the small angle x‐ray scattering intensity, correlating to an increase in the number of tie molecules.

increase in molecular chain length for reducing the intermolecular chain slip at polymer chain ends.

increase the slope of the Griffith plot, a manifestation of reducing defeets and flaws in microfibrils.
Post‐curing of dental restorative resin
Authors: Wu W. , Fanconi B. M.
Published: December 2004

The post‐curing of a bisphenol A‐glycidyl‐methacrylate based copolymer system at 37°C and 100 percent relative humidity was monitored using Fourier Transform IR (FT‐IR). The dependence of degree of post‐curing on the monomer and initiator components was investigated. The further polymerization achieved by elevating the temperature was measured using differential scanning calorimetry (DSC). The results clearly demonstrated that this free radical curing process was severely quenched by vitrification. Furthermore, a rapid loss in the reactivity to further curing was observed for the material in the quenched state, and this loss in reactivity was attributed to the decay of free radicals.
Properties of phenolic fiber‐reinforced polymers
Authors: Broutman L. J.
Published: December 2004

Fibers made of phenol formaldehyde are relatively new to the market place and are currently manufactured in Japan. They have certain characteristics which make them attractive as a reinforcement for rubber, thermoplastics, and thermosets. This paper will discuss the properties of molded polypropylene thermoplastics as a function of fiber weight percent and surface treatment. It is shown that the elevated temperature properties are improved without sacrifice of low‐temperature brittleness.
Injection molding of thermotropic liquid crystal polymers
Authors: Ophir Zohar , Ide Yoshiaki
Published: December 2004

Thermotropic liquid crystal polymers consist of rod‐like molecules and are often called “self reinforcing thermoplastics.” Their rheological behaviors as well as orientation development during processing are often very similar to those of short fiber‐filled composites. Without reinforcement, the polymer shows superior mechanical properties to conventional glass fiber‐reinforced engineering resins. The orientation distribution in the crosssection as well as flow patterns in the molded thermotropic polymers are clearly visible to the naked eye due to color differences. This makes it particularly convenient to study the orientation distribution as well as the flow patterns of packing, back flow, jetting, flow instabilities, and weld line formation in injection molding. This paper discusses physical properties of a typical ther motropic polymer and their relationship to mold filling process in the injection molding.
The rheology and spin coating of polyimide solutions
Authors: Jenekhe Samson A.
Published: December 2004

The rheological properties of five types of concentrated polyamic acid and polyimide solutions are characterized by non‐Newtonian shear viscosity η(\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \dot \gamma} $\end{document}) and primary normal stress coefficient Ψ1(\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \dot \gamma} $\end{document}) measurements over a wide range of shear rates. Onset of non‐Newtonian flow of the polyamic acid solutions was observed in the shear rate range 30 to 400s−1 and of the fully imidized polyimide solution at below 3 × 10−2s−1. Significant viscoelastic properties exemplified by normal stresses were observed in all the solutions. The solution rheology results are discussed in the context of spin coating for the deposition of thin films. The relative magnitude of effects of non‐Newtonian flow on the dynamics of spin coating is assessed with a Deborah number characteristic of the flow.
Viscoelastic behavior of amorphous polymers in the glass‐rubber transition region: Birefringence studies
Authors: Read B. E.
Published: December 2004

Viscoelastic processes associated with the glass‐rubber transition of an amorphous polymer are considered to involve hindered rotations around main‐chain bonds, which give rise to a decrease in molecular distortion in the stressed material and to an orientation or disorientation of chain segments. The local distortional changes are associated with variations in energy‐elastic stress. The orientational rearrangements yield changes in conformational entropy and energy and may be described in the long‐time region by the normal mode motions of Gaussian submolecules. Assuming that the net time‐dependent stress and birefringence may each be expressed as the sum of distortional and orientational contributions, methods are proposed on the basis of stress‐optical data for resolving the distortional and orientational stresses or moduli during stress‐relaxation, creep, and dynamic mechanical tests. An analysis of dynamic birefringence data for different amorphous polymers indicates that the orientational processes become important in the long relaxation‐time region and are consistent with predictions of the submolecular theory. The distortional changes dominate the shorter relaxation‐time behavior and are characterized by somewhat narrower distributions of relaxation times than are apparent from the unresolved data.
Block polymers. Characterization and use in polymer blends
Authors: Bywater S.
Published: December 2004

Polymer blends, because of the well‐known immiscibility of polymers, generally show phase separation. Block polymers can be considered as simple models of two‐phase systems. Because unlike segments are connected by covalent bonds, the phase separation is on a smaller scale and takes rather unusual forms. The types of block polymers of commercial importance are described with a consideration of the morphologies which result from particular compositions. Their use as solubilizing agents to increase the compatibility of the corresponding homopolymers is also discussed.
Some observations on kinetic and steric limitations to specific interactions in miscible polymer blends
Authors: Garton Andrew
Published: December 2004

This note describes the application of infrared spectroscopy to determine the proportion of ester groups of poly(ϵ‐caprolac‐tone) which are involved in specific interactions with the hydroxyl groups of the poly(2‐hydroxypropyl ether of bisphenol A) (Phenoxy, Union Carbide) in a series of miscible blends of the two polymers, Even with a fifteen‐fold excess of hydroxyl groups, only about 50 percent of the ester groups of poly(ϵ‐caprolactone) are hydrogen‐bonded, presumably reflecting steric restrictions to the ester‐hydroxyl interactions. Partially miscible blends of these two polymers may also be prepared by a suitable choice of casting solvent, and infrared spectroscopy may then be used to follow the kinetics of miscibility when the partially miscible blend is heated.
The composition‐dependent glass transition: Relations between temperature pressure, and composition
Authors: Couchman P. R.
Published: December 2004

A new predictive relation between pressure and temperature changes on the glass‐transition boundary is derived for random solutions. The isobaric version of this relation is integrated to recover a previous theory for the compositional variation of glass‐transition temperatures. The isothermal form of the differential equation gives an equation for the compositional variation of glass‐transition pressures. An enthalpic definition of the transition boundary provides a relation between excess enthalpies of mixing for the glassy and liquid states for the isobaric and isothermal transitions. Similarly, a definition of the boundary in terms of the solution volume provides a relation between excess volumes of mixing for these two states for the isobaric and isothermal transitions. The primary entropic equation for the composition‐dependent isobaric transition gives two hierarchies of approximation, one of which is shown to be preferred for physical reasons. A parallel situation arises for the isothermal transition.
Dielectric properties of poly(α‐methyl α‐n‐propyl‐β‐propiolactone)/poly(vinyl chloride) blends
Authors: Malik Tariq M. , Prud'Homme Robert E.
Published: December 2004

The dielectric properties of miscible blends of poly(vinyl chloride) (PVC) and poly(α‐methyl‐α‐n‐propy‐β‐propiolae‐tone) (PMPPL) have been investigated at different temperatures above and below Tg. The results were analyzed using the Cole‐Cole representation and lead to the conclusion that this mixture does not exhibit micro‐scale heterogeneities. Dielectric constant and dielectric loss master curves were constructed using the stress relaxation shift factors determined previously; the same shift factors could be used for the homopolymers and their blends. Similarities between the dielectric master curves and the stress relaxation master curves of PVC, PMPPL, and their blends, are also discussed.