bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystallization in poly(c/s‐1,4‐cyclohexane dimethanol sebacate) model networks in the unstrained and strained states
Authors: Riande E. , Guzman J. , Mark J.E. 
Published: December 2004

AbstractRates of crystallization, stress‐optical coefficients, and melting points were determined for unelongated and elongated polysebacate model networks. For the unelongated networks, the maximum rate of crystallization was found to occur at approximately 0°C. For the elongated networks, the stress‐optical coefficients documented the extent to which strain‐induced crystallization was facilitated by increase in elongation and decrease in temperature. Measurements of stress relaxation due to crystallization at constant elongation indicated that the dimensionality of crystallization growth decreased from 3.0 to 2.5 as the temperature increased Melting points increased significantly with increase in elongation as predicted by theory. Fiber (non‐equilibrium) shrinkage temperatures, as expected, showed no correlation with the melting points.
Flame retardation of polypropylene: Effect of organoantimony compounds on the melt flow behavior
Authors: Jha N. K. , Misra A. C. , Bajaj P. 
Published: December 2004

AbstractThe melt flow behaviour of polypropylene filled with organoantimony compounds, triphenylstibinedibromide and its derivatives with tribromo‐, trichloro‐, and pentachloro‐phenols, as flame retardants has been studied in the temperature range of 180 to 220°C, and at shear rates of 29.5 to 588.8's−1, using a capillary rheometer. A decrease in the melt viscosity at all shear rates and temperatures was noticed on addition of these flame retardants, The melt viscosity further decreased upon increasing the concentration (from 5 to 20 phr) of the flame retardants. The die swell was measured in order to determine the melt elasticity of the filled systems. The minimum melt viscosity of filled propylene was observed approximately where the maximum die swell (melt elasticity) occurred.
Acoustic waveguide monitoring of the cure and structural integrity of composite materials
Authors: Harrold R. T. , Sanjana Z. N. 
Published: December 2004

AbstractWe have investigated the use of acoustic waveguide techniques to measure the cure and stress state of epoxy resins and composites. It is anticipated that the waveguides, which are incorporated within the structure, will also be valuable for nondestructive (NDE) evaluation of stress, strain, and damage caused to the structure during its life time. While dielectric techniques are commonly used to monitor the cure of composites, they suffer because metal electrodes intrude into the structure and poor signal‐to‐noise ratios may be encountered with graphite composites. Acoustic waveguides can be made compatible with the host structure and after the cure monitoring function is over, remain in the structure for NDE of flaws and voids, as well as to monitor other parameters. This paper presents results on experiments to monitor the cure and stress state of resins and composites with a 1.5 mm diameter polyester‐fiberglass acoustic waveguide in curing resin. A 1000 to 1 change in the peak value of a 71 kHz acoustic signal was found. Other parameters now being investigated are: frequency of transmission and phase change, transit time, waveguide size and shape, and acoustic wave attenuation characteristics.
The use of melt strength of low density polyethylene as a processability measure in film blowing extrusion
Authors: Montes Sergio A. , Ramírez José L. 
Published: December 2004

AbstractThe melt strength method is analyzed in terms of its ability to predict the axial stress levels found in tubular film extrusion of low density polyethylene. For certain values of the capillary L/D, the level of axial stresses and average Newtonian viscosity found in the filament stretching and film blowing are comparable at the same draw ratio. The elongation to break of the finished film was found to be primarily determined by the axial stress during the film blowing, at constant frost line height.
Phase continuity and inversion in polymer blends and simultaneous interpenetrating networks
Authors: Jordhamo G. M. , Manson J. A. , Sperling L. H. 
Published: December 2004

AbstractA semi‐empirical expression for predicting phase continuity and inversion in polymer blends and simultaneous interpenetrating networks (SINs) was developed and examined experimentally. A rheological model based on the volume fraction, ϕ, and viscosity, η, led to the equation

as the criteria for dual phase continuity for phases 1 and 2. This relation was evaluated for two systems: a castor oil polyester‐urethane/polystyrene SIN, and a mechanical blend of polystyrene and polybutadiene. Literature data was also examined. A gradual phase inversion was found, with a region of dual phase continuity in between. While predictions of phase continuity were confirmed for the mechanical blends, they were not confirmed for the SIN system. This was probably due to rapid gelation at the point of phase inversion.
The kinetics of the in situ polymerization of glycidyl methacrylate in wood using dynamic mechanical measurements
Authors: Balaba W. M. , Subramanian R. V. 
Published: December 2004

AbstractThe in situ polymerization of glycidyl methacrylate in wood, in the presence of uranyl nitrate, (UN), and/or 2,2′‐azo‐bis‐isobutyronitrile, (AIBN), has been investigated in the temperature range 55°‐72°C. The course of the polymerization reaction was followed by measurement of tan 5 in an automated Rheovibron viscoelastometer. The kinetics, studied by applying the Guggenheim method to the data, showed the polymerization to be first order whether catalyzed by UN or initiated by AIBN. The activation energy (Eα) for AIBN‐initiated polymerization was 121 kJ/mol, and was unaffected by varying monomer concentration in acetone. On the other hand, Eα for the UN‐catalyzed polymerization was found to be 59.1 and 73.5 kJ/mol respectively for the neat and 50 percent monomer concentration reaction mixture. The enhancement in Eα is attributed to the complexatton of the dioxouranium (VI) ion in the presence of solvent acetone, with consequent reduction in catalytic activity.
Dimensional stability of polystyrene/polymeric liquid crystal blends
Authors: Apicella A. , Iannelli P. , Nicodemo L. , Nicolais L. , Roviello A. , Sirigu A. 
Published: December 2004

AbstractRecovery experiments above Tg have been performed on polymeric liquid crystal (PLC) ‐ polystyrene (PS) blend sheets obtained from extrusion and subsequent hot drawing. The data reported show that a significant improvement of the dimensional stability of a drawn thermoplastic material can be obtained by adding a low percentage of non‐compatible polymeric liquid crystals that are oriented during the hot drawing process. The fibrils formed act as a constraint for a certain amount of polymer surrounding them and consequently these highly oriented sheets, once exposed to high temperature, will mainly stress relax and do not creep. This effect disappears when the melting temperature of the oriented crystalline phase is reached. Compatible PLC‐PS blends do not show any improvement on the dimensional stability compared to the unfilled matrix.
Multiple crazing at crack tips in PVC under plane strain conditions
Authors: Lee L. H. , Mandell J. F. , Mc Garry F. J. 
Published: December 2004

AbstractThe nature of the yield zone at the crack tip of poly(vinyl chloride) (PVC) pipe materials has been investigated. Microscopy studies employing a plasma etching technique reveal the presence of multiple crazes ahead of the crack tip in the interior of specimens of pure PVC, CaCO3 filled PVC, and PVC pipe compound. The craze zone and the fracture toughness of blade‐notched specimens are compared with those of fatigue pre‐cracked specimens. Both types of specimens have similar fracture toughness values and form multiple crazes upon loading, suggesting that multiple crazing Is an intrinsic property of the material. The kinetics of craze initiation and the development of the multiple craze zones have also been explored.
An injection molding study. Part I: Melt and barrel temperature dynamics
Authors: Kamal M. R. , Patterson W. I. , Gomes V. G. 
Published: December 2004

AbstractThe dynamics of the key variables in the plastication phase of injection molding were studied using a microcomputer controlled laboratory scale injection molding machine. Interfaces for the measurement and manipulation of suitable variables were developed. An approximate theoretical analysis provided a preliminary understanding of the effect of a step input in heating power on melt and barrel temperatures. Deterministic and stochastic models were derived from experimental data for the melt and the front and rear zone barrel temperatures with heater power manipulation. Experiments were performed for evaluating the effects of back pressure manipulation, heating zone interaction, and process disturbances on the melt and barrel temperatures. Experiments showed that it is desirable to directly control the melt temperature rather than the barrel temperatures.
An injection molding study. Part II: Evaluation of alternative control strategies for melt temperature
Authors: Gomes V. G. , Patterson W. I. , Kamal M. K. 
Published: December 2004

AbstractMelt temperature is a key variable of the injection molding process. The evaluation of different control strategies for the melt temperature was based on the process dynamics presented in Part I of this work. The controllers tested were: PID (proportional‐integral‐derivative) control of barrel temperatures, direct PID control of melt temperature, Dahlin control, and Smith Predictor control of melt temperature. The controllers were tuned by simulation studies and were evaluated by a comparison of performance indices. The controller responses obtained through experiments were evaluated by comparing the rise time, peak overshoot, damping, settling time, and control effort. Analyses were performed to ascertain the sensitivity characteristics of the controllers.
Boundary conditions in the modeling of injection mold‐filling of thin cavities
Authors: Soh Sung Kuk , Chang Chin Jui 
Published: December 2004

AbstractA governing equation for injection mold‐filling of thin cavities with a power‐law fluid is derived. The interaction between upstream delivery channel flow and cavity flow results in a continuously changing gate condition as the total viscous dissipation of the delivery channel‐cavity assembly is minimized. Depending upon the relative magnitude of pressure drops or viscous dissipation across the channel and the cavity, the boundary conditions which determine the cavity filling process will lie between the following two limiting cases: a Cauchy type gate condition such that the location of the melt front is completely determined by the upstream flow; a Cauchy type melt front condition in which the gate condition is controlled by the downstream flow. For most injection molding cases this may be manifested as equilibration of dissipation density on the melt front. Experimentally observed melt front locations from isothermal, Newtonian filling of a constant gap rectangular cavity and of a bi‐gap rectangular cavity are reported and the validity of the limiting cases are tested.
Adhesion and the surface behavior of the silicone elastomer RTV‐142
Authors: Bretzlaff R. S. , Freitag T. A. , Lee Andréa 
Published: December 2004

AbstractThe silicone elastomer RTV‐142 is often used as a particle‐getter material inside electronics packages. The adhesion mechanism that forms the bond between the particle and the cured adhesive has been investigated. One expects, theoretically, that polymer chains exhibit a temperature‐dependent mobility. This is consistent with the hypothesis that the flow of polymer chain segments around asperities on the foreign particles causes adhesion. Calculations of the surface energy of an idealized polymer system are presented which support the concept of a free‐energetically driven flow of chain segments into pores and around asperities. Polymer surface‐chain mobility is investigated experimentally by the scanning electron microscope analysis of a fractured, cut, and particle‐decorated surface. Surface appearance changes were noted as a function of temperature. Scanning electron micrographs indicate that polymer chain movement is temperature dependent. Such findings support the proposed adhesion mechanism.
Rheological and mechanical properties of poly(vinyl chloride)/chlorinated poly(vinyl chloride) miscible blends
Authors: Lehr Marvin H. 
Published: December 2004

AbstractThe properties of poly(vinyl chlorlde)/ehlorinated poly(vinyl chloride) (61.6 percent C1) blends, prepared by melt and solution blending, were measured by various tests. Based on the chlorinated poly(vinyl chloride) (CPVC) composition, percent chlorine, and mole percent CC12 groups, these blends were expected to show intermediate properties between miscible and immiscible systems. Indicative of miscible behavior were the single glass transition temperatures over the entire composition range for both melt and solution blended mixtures. A single phase was also indicated by transmission electron microscopy. However, the yield stress showed a minimum value less than either of the pure components in the 50 to 75 percent CPVC range, which is characteristic of two‐phased systems. Specific volume, glass transition temperature, and heat distortion temperature were linear with binary composition. The storage modulus showed a small maximum, suggesting a weak interaction between the two miscible polymers. Heats of melting for the residual PVC crystallinity were also less than expected from linear additivity. At 160°C and 210°C, the logarithm of the complex viscosity was essentially linear with volume fraction of CPVC, except for a very slight decrease in the 50 to 75 percent CPVC range, which may have been a result of lower crystallinity. At 140°C, the complex viscosity of the CPVC was less than that of PVC owing to the higher crystallinity of the latter. The viscosities were similar at 160°C, but at 210°C, where most of the crystallites had melted, the complex viscosity of the CPVC was higher because of its higher glass transition temperature.
Power consumption of partially filled twin‐screw extruders
Authors: Secor R. M. 
Published: December 2004

AbstractTwin‐screw extruders are used very effectively, when partially filled, for mixing and surface renewal of high‐viscosity fluids. The rate of energy input, often sufficiently high to be a major design consideration, determines the drive power, the heat input to the fluid, and the cooling requirements. Operating limitations may be fixed by thermal degradation of the material being processed. A simple model for the rate of energy dissipation in twin‐screw extruders predicts that the power input is proportional to the square of the screw speed. Measurements were made of shaft torque and screw speed for polyisobutylene passing through a large twin‐screw extruder having co‐rotating shafts. The experimental procedure avoids the problems of changes in holdup and temperature that accompany changes in screw speed under steady state conditions. The power input was found to be proportional to the screw speed raised to the exponent 1.90. This result was attributed to slightly pseudoplastic behavior of the fluid in the radial clearances.
Optimization of nonvaporizing nylon 6 reactors with stopping conditions and end‐point constraints
Authors: Ray Ajay K. , Gupta Santosh K. 
Published: December 2004

AbstractIn this study, optimal temperature profiles (or histories),T(t), are obtained for nonvaporizing plug‐flow (or batch) Nylon 6 reactors using the minimum principle. Two objective functions are studied, one in which the monomer conversion, convtf, is maximized, and the other in which the undesirable side product (cyclic dimer) concentration in the output stream, [C2]tf, is minimized. The control variable, temperature, is constrained to lie between 220°C and 270°C in order to ensure single phase polymerization. The most significant difference between this study and earlier ones is that the residence (or reaction), time tf, is not specified a priori, but is determined optimally by the use of a ‘stopping’ condition such that the polymer product has a number‐average chain length, μn, equal to some desired value μn.d. Simultaneously, an end‐point constraint is used, which, depending on the objective function used, forces either the cyclic dimer concentration or the monomer conversion at the end of the reactor to lie at a specified value, [C2]d or convd. Thus, this algorithm incorporates stopping conditions as well as end‐point constraints and so is more complex than earlier ones, but the results are more meaningful. Different nonisothermal optimal temperature profiles are obtained for the two objective functions studied, depending on the values of μn.d, convd, [C2]d, and the feed water concentration, representing the complex interplay of several opposing factors.
A negative resist, LMR (low molecular weight resist), for deep UV lithography
Authors: Itoh Toshio , Yamashita Yoshio , Kawazu Ryuji , Kawamura Kazutami , Ohno Seigo , Asano Takateru , Kobayashi Kenji , Nagamatsu Gentaro 
Published: December 2004

AbstractA negative deep UV resist, LMR, has been developed. LMR is a diazonaphthoquinonesulfonate of cresol novolac resin and possesses a high sensitivity of 15 mJ/cm2 and a high resolution up to 0.2 μm by contact printing. An important feature of LMR is the production of negative images with overhung profiles. Such profiles are attributed to LMR possessing a large absorbance in the deep UV region (12 μm−1 at 250 nm), which is of great advantage to the lift‐off process in the fabrication of GaAs‐FET, surface acoustic wave (SAW) devices, and so on. Furthermore, because of the good thermal stability of LMR, it can liftoff hard metals such as Ni and Mo. In order to elucidate the phenomenon that deep UV irradiation retards the dissolution rate of LMR, a mechanistic study has been carried out. In both LMR and its analog lacking diazoquinone moiety, their molecular weights Increase upon deep UV irradiation, which suggests that crosslinking occurs in the base resin. This is supported by 13C NMR analyses of photochemical reaction products and by detection of radical species produced from the base resin. The photochemical reaction of the base resin is important to understand the overall lithographic performance of LMR.
Spun‐On contour coating characterizations for advanced optical lithography
Authors: White L. K. 
Published: December 2004

AbstractSpun‐on contour coating properties are characterized for two absorptive undercoats, AUCs, and a contrast‐enhanced layer, CEM‐388. A low‐pass frequency filter contour modeling procedure is used to simulate the coating contours on a real silicon‐on‐sapphire epi‐island layout. The computed thickness variations are used to estimate the variation in optical densities of these spun‐on films on the topography. The variations in optical densities arc discussed in terms of the expected dimensional deviations introduced into the patterned resist layer. At the same spun‐on thickness, one absorptive undercoat offers improvement in dimensional control when compared to the other. Changes in the thickness of the CEM‐388 layer may also introduce significant dimensional deviations in the underlying positive resist layer. In, both cases the more conformal spun‐on contour coating properties produce improved resist imaging.
Excimer laser projection patterning with and without resists
Authors: Ehrlich D. J. 
Published: December 2004

AbstractProjection imaging with the deep‐UV (193 nm) and VUV (157 nm) output of an excimer laser has been applied to submicrometer patterning of thin films by injected‐defect, surface‐chemical, and solid‐transformation processing. The methods have been designed to take advantage of the short‐wavelength, high‐peak‐intensity pulsed radiation from these sources. Examples are described of pattern definition by exposure of multilayer organic resists, by maskless etching and doping of solids in reactive vapors, and by solid‐state chemical transformations in inorganic Al/0 films. Well‐resolved 0.4‐μm lines and spaces have been achieved. Required doses, between 0.04 and 1 J/cm2, are compatible with single‐ or multi‐pulse step‐and‐repeat projection patterning with a small excimer laser.
Dry developable resist in e‐beam and sr lithography
Authors: Tsuda Minoru , Oikawa Setsuko , Yabuta Mitsuo , Yokota Akira , Nakane Hisashi , Atoda Nobufumi , Hoh Koichiro , Gamo Kenjj , Namba Susumu 
Published: December 2004

AbstractDry developable resists comprised of poly(methyl isopropenyl ketone) (PMIPK) and 4‐methyl‐2,6‐dI‐(4′‐azldoben‐zylidene)‐cyclohexanone‐1 gave excellent results in SK lithography, i. e., high aspect ratio resist patterns with vertical walls were easily obtained by maskless dry etching in the single layer resist process. Because of the simplicity of single layer resist processing and the high etch rate in maskless dry etching for the formation of thick resist patterns, the dry developable resist in SR lithography may be advantageous to the multilayer resist for the purpose of generating high resolution, thick resist patterns with vertical walls. The resolution limit of the dry developable resist which reproduces the designed dimensions was 100 nm line and 200 nm space when a conventional e‐beam apparatus was used at 20 KV in the dry developable multilayer resist process.
Synchrotron lithography: The way to sub‐micron features with single layer resists
Authors: Huber H.‐L. , Betz H. , Heuberger A. 
Published: December 2004

AbstractSoft X‐ray radiation is affected neither by scattering in the resist nor by reflection from the substrate surface, so that a one‐layer resist system can be maintained even in the sub‐micron range. This holds primarily for the parallel synchrotron radiation avoiding all the geometrical distortions connected with X‐ray tubes and even plasma sources. It has been shown that a minimum feature size of 0.2 μm can be achieved in this case. Different resist systems applicable in X‐ray lithography have been tested regarding resolution, sensitivity, and etch stability. The optical resists Kodak ‘HPR 204’ shows very high process stability, good resolution, but low sensitivity. It is, therefore, suitable for an X‐ray pilot process but not for high throughput production. The high sensitive X‐ray resist TBM 120′ a fluorized poly(methyl methacrylate) which shows originally a very poor etch stability can be stabilized by post exposure with synchrotron radiation.
Solute diffusion in swollen membranes. Part V: Solute diffusion in poly(2‐hydroxyethyl methacrylate)
Authors: Moynihan Humphrey J. , Honey Martha S. , Peppas Nikolaos A. 
Published: December 2004

AbstractStudies with phenylalanine diffusing in well‐characterized poly(2‐hydroxyethyl methacrylate) (PHEMA) membranes swollen in water at 37°C were conducted. Films were prepared by reaction of HEMA monomer with the cross‐linking agent ethylene glycol dimethacrylate (EGDMA) at cross‐linking ratios, X, of 0.005, 0.01, 0.0128, 0.025, and 0.050 mole EGDMA/mole HEMA in the presence of 40 weight percent water at 60°C for 12 hours. These membranes were subsequently swollen in water at 37°C and their structure analyzed using a modified Gaussian distribution equation of swelling. The calculated values of M̄c varied between 1,700 and 3,425 daltons, which corresponded to a correlation length of the mesh size, egr, of 24 to 35 A. The phenylalanine solute diffusion coefficient varied from 0.17 × 10−6 to 0.97 × 10−6 cm2/s, and depended on the aforementioned structural parameters of the membranes.