bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of the influence of process factors on plasma developed X‐ray resist properties
Authors: Taylor G. N. , Hellman M. Y. , Feather M. D. , Willenbrock W. E. 
Published: May 2005

AbstractUV spectroscopy, gel permeation chromatography (GPC) and liquid chromatography (LC) have been used to analyze process factors that influence the properties of PDXR‐2 plasma developed X‐ray resist comprised of 92.5 wt percent poly(2,3‐dichloro‐1‐propyl acrylate) and 7.5 wt percent bis‐acryloxybutyltetramethyldisiloxane (BABTDS). The GPC‐LC method is particularly useful in optimizing fixing conditions, determining monomer concentration in the film, and studying molecular processes caused by absorbed X‐rays and thermal effects during fixing. Evidence for a synergistic sensitivity enhancement resulting from fixing and exposure is presented. Optimally processed O2 reactive‐ion etch developed patterns exhibit a microgranular texture in both exposed and unexposed regions of <500 Å size. Unexposed region texture consists of SiO2 resulting from the BABTDS monomer. It is completely removed by reactive ion etching with CHF3 for short times at low power. The exposed area texture is not removed and affords an edge roughness per line edge of <500 Å. Resolution appears mask limited while granular size is dependent on exposure time. A 20 sec exposure optimizes resolution, pattern uniformity, and granularity. 0.5 μm line and space resolution can be obtained with the X‐ray machine and masks currently in use.
Materials for multilevel resist schemes
Authors: Reichmanis E. , Wilkins C. W. , Ong E. 
Published: May 2005

AbstractBilevel resist processing techniques, offering the advantage of forming images on a planar substrate, and thus improving the resolution capability of optical projection printers are discussed. After careful consideration of such materials characteristics as UV absorption, solubility, compatibility, and Tg, practical schemes can be developed, the simplest of which is one that uses conventional novolak‐quinone diazide positive resists as the top masking layer and short wavelength sensitive methacrylate based resists to planarize the substrate. Sub‐micron resolution and excellent line‐width control are achieved in these systems.
Organosilicon polymers for lithographic applications
Authors: Shaw J. M. , Hatzakis M. , Paraszczak J. , Liutkus J. , Babich E. 
Published: May 2005

AbstractLinear polymers of silicone gums (polysiloxanes) have many attributes that make them attractive for lithographic applications, such as oxidative and thermal stability, good adhesion properties, solubility in common solvents, and resistance to etching in an oxygen plasma. When polysiloxanes are used as the top imaging layer (∼2000Å) in a two‐layer resist system, the developed negative siloxane images act as a high resolution etch mask for the oxygen plasma etching of the bottom planarizing polymer layer. Commercially available polysiloxanes have been evaluated for their deep UV sensitivity at 2537Å, and have been found to have very high resolution capabilities (∼0.5μ) and high contrast (γ = 4). The negative images do not swell in the developer, and the line width is therefore independent of development time. The combination of high resolution, sensitivity, and ease of processing make this a simple multilayer system for deep UV and e‐beam applications.
The disentanglement time of the craze fibrils under cyclic loading
Authors: Schirrer R. , Masson J. Le , Tomatis B. , Lang R. 
Published: May 2005

AbstractIn a previous publication a breaking or disentanglement‐time was defined for the fibrils in the craze at the tip of a steady‐state moving crack. In this paper the case of a cyclic sinus loading is investigated, whereas in the previous one the case of a static loading was studied. In both cases the craze fibrils break due to a thermally activated process. The apparent activation energy corresponds to that of the secondary relaxation peak (b̃) in poly(methyl methacrylate). Under cyclic loading conditions the breaking time may be expressed as a time or as a number of cycles carried by the fibrils before breakage. It seems that the relevant parameter is the time rather than the number of cycles. At high frequencies and temperatures an hysteretic heating effect has been detected by means of the breaking‐time of the fibrils.
Orientation in amorphous polymers I. Preparation and testing of oriented samples
Authors: Vrentas J. S. , Vrentas C. M. , Bhombal A. H. , Lahalih M. S. 
Published: May 2005

AbstractOrientation effects in amorphous polystyrene are studied using a uniaxial stretching experiment. The rheological properties of the polymer are determined from an analysis of creep data obtained from the tensile apparatus, and oriented polymer samples are prepared at different extension ratios and rates of stretching. From birefringence and tensile strength measurements on oriented samples of polystyrene, it is shown that the tensile strength is not a unique function of the birefringence. It is proposed that the tensile strength may depend not only on the average orientation, as reflected by the birefringence, but on which portion of the relaxation spectrum is preferentially oriented.
Polymer blends from polyurethane and poly(methyl methacrylate) by reaction injection molding
Authors: Kircher K. , Mrotzek W. , Menges G. 
Published: May 2005

AbstractThe simultaneous production of polyurethane (PUR) and polymethyl methacrylate (PMMA), starting from a mixture of polyol, polyisocyanate, and vinyl monomer, results in 2‐phase polymer alloys. A simultaneous crosslinking of the PMMA is unable to prevent phase separation during the curing reaction; interpenetrating polymer network (IPN) structures were not found, Grafting the PMMA onto the PUR through the incorporation of 2‐hydroxyethylacrylate resulted in single‐phase systems. Various material combinations did not show, with a relatively high PMMA content, any poorer properties than the straight PUR. A major advantage of incorporating low‐viscosity vinyl monomers lies in the fact that high‐viscosity polyurethane starting components that are otherwise difficult or impossible to process can be processed here without problem.
Thermal stability of polyethylene terephthalate
Authors: Jabarin S. A. , Lofgren E. A. 
Published: May 2005

AbstractThe kinetics of thermal and thermal‐oxidative degradation of polyethylene terephthalate (PET) have been investigated as a function of melt temperature, melt residence time, melt environment, and drying environment. Rates of thermal and thermal‐oxidative degradation were measured in terms of: weight loss of volatile degradation products, decreasing inherent viscosity, and increasing carboxyl end group concentration. Thermal‐oxidative degradation was also investigated by Differential Scanning Calorimetry. Calorimetric results show that thermal‐oxidative degradation of PET is an exothermic reaction, with an apparent activation energy of 117 kJ/mol. Melt temperature, melt residence time, melt environment, and drying environment have all been found to affect the degradation of PET. Analysis of inherent‐viscosity kinetic data has been carried out, utilizing existing theories based on a random chain scission mechanism. Activation energies of 117 and 159 kJ/mol have been calculated for air‐dried and vacuum dried samples respectively.
New model of physical aging effects in enthalpy recovery
Authors: Rendell R. W. , Lee T. K. , Ngai K. L. 
Published: May 2005

AbstractA new model of enthalpy recovery is presented which is based on a microscopic‐relaxation theory. The microscopic basis and manner of construction of the enthalpy‐recovery model are discussed in detail. The qualitative features of the model are illustrated using numerical simulations. In particular, the way in which the effects of physical aging are produced is discussed. The qualitative features observed in differential‐scanning‐calorimetry experiments are reproduced, and a program of extensive simulations is proposed and outlined. The present microscopically based model is also used to suggest interpretations and possible modifications of currently used phenomenological enthalpy recovery models.
Physical aging of poly(methyl methacrylate) in the nonlinear range: Torque and normal force measurements
Authors: McKenna G. B. , Kovacs A. J. 
Published: May 2005

AbstractCylindrical specimens of poly(methyl methacrylate) (PMMA) were quenched from above the glass transition and subsequently tested in torsion. Torque and normal‐force relaxation responses were recorded simultaneously. The experiments were performed at 40, 60, and 80°C, at increasing aging times and at deformations ranging from γ = 0.0027 to γ = 0.074. It was found at 40 and 60°C, that, contrary to the classical picture of aging, the small‐deformation torque‐relaxation curves could not be superposed by any combination of vertical and horizontal shifts. On the other hand, at 80°C, and in the nonlinear deformation range even at lower temperatures, the relaxation curves are superimposable simply by horizontal shifts, but as γ increases they involve decreasing values of the double‐logarithmic shift rate. At the same deformation level, however, the shift rate for the normal force is significantly higher than is that for the torque over most of the γ range investigated.
Kinematics, dynamics and stability of the tubular film extrusion of various polyethylenes
Authors: Kanai Toshitaka , White James L. 
Published: May 2005

AbstractA basic study of the kinematics, dynamics, and heat transfer occuring during tubular film extrusion of polyethylene is outlined. Three rheologically characterized polyethylenes, a low‐density polyethylene (LDPE), a linear‐low‐density polyethylene (L‐LDPE), and a high‐density polyethylene (HDPE) were used in this study. The kinematics and stability of the tubular film process were investigated over a wide range of blow‐up ratios, drawdown ratios, and frost‐line heights. Local deformation rates along the bubble have been determined. Regions of stability and instability are described. Tensions and inflation pressures have been measured and expressed in terms of locol elongational viscosities. Temperature profiles along the bubble were determined and interpreted in terms of local heat transfer coefficients. Positions of crystallization and temperature profiles have been noted and used to estimate rates of crystallization. The characteristics of the LDPE, LLDPE, and HDPE are contrasted.
Thermal catalytic polymerization of mortars impregnated with styrene‐acrylonitrile
Authors: Gadalla Ahmed M. , El‐Derini Mohamed E. 
Published: May 2005

AbstractStandard test specimens of mortar were cured under water for 15 days to achieve satisfactory strength. They were dried without allowing dehydration reactions to occur, evacuated to 40 millimeters (mm) Hg, and impregnated with a styreneacrylonitrile comonomer, which gives the highest strength after polymerization. Positive pressure of 0.6 N/mm2 was applied and thermal catalytic polymerization was carried out. Optimum initiator concentration was found to be 2 percent. Strength (compressive and tensile) increases with polymerization temperature up to 120°C, above which rapid deterioration occurs due to monomer loss, production of short chains with high polymerization rates, and the possibility of polymer degradation at high temperature. Optimum polymerization period of' 10 hours was selected. Inexpensive methods for field polymerization were tried at 95°C. Hot water yields a strength more than double that obtained with a, flow of hot air and about 80 percent of that obtained radiolytically. While hot air accelerates evaporation, hot water forms a hydraulic head above the capillaries and decreases the monomer losses tremendously.
A note on the role of diffusion during the inflation of a tubular viscoelastic film
Authors: Chung Tai‐Shung 
Published: May 2005

AbstractA mathematical simulation of the effect of diffusion on the inflation of a cylindrical polymer film has been developed. The rheological constitutive equation of polymer was assumed to obey an Oldroyd fluid B type. Calculated results indicate that the diffusion coefficient and solubility of the gas have a profound influence on the film or membrane expansion.
Free radical solution oligomerization of styrene in a continuous‐stirred tank reactor train
Authors: Hsu Keh‐Ying , Chen Show‐An 
Published: May 2005

AbstractFor free radical oligomerization of styrene, a scheme for calculating the molecular weight distribution and conversion in a continuous‐stirred tank reactor (CSTR) train is developed, which also allows the calculation of molecular weight distribution (MWD) for batch reaction. Calculations show that under conventional or near dead‐end condition: (1) increasing initial initiator concentration, reaction time and reaction temperature, and decreasing initial monomer concentration cause P̄n and P̄w to decrease and MWD to narrow; (2) increasing initial initiator concentration, reaction time and reaction temperature, and increasing monomer concentration cause monomer conversion to increase; (3) a single CSTR gives a lower rate of oligomer production, but a narrower MWD than does a batch reactor.
Measurement of mixing in polymer melts by focused ultrasound
Authors: Erwin Lewis , Dohner Jeffery 
Published: May 2005

AbstractThis paper outlines the development of an acoustical technique for measuring the dispersion of an additive in a polymer melt. It included a justification of the use of sound over other interrogating methods and an analysis of the acoustical system's operation. Results for dispersions of liquid or solid additives were shown. It was demonstrated that this system could detect the presence or absence of large particles in melts filled with small particles.
Radiation‐degradation susceptibility studies of vinyl terpolymers: Search for improved electron beam resists
Authors: Wallace Easley , Chen Chi‐Yu , Pittman Charles U. , Kwiatkowski Joe H. , Cook Charles F. , Helbert John N. 
Published: May 2005

AbstractTo develop polymer systems with improved lithographic resist properties, terpolymers of methyl methacrylate/methacrylonitrile/methyl α‐chloroacryate (MMA/MCN/MCA), methyl methacrylate/methacrylonitrile/α‐chloroacrylonitrile (MMA/MCN/ACAN), and methyl methacrylate/methacrylonitrile/vinylidene chloride (MMA/MCN/VDC) were prepared by emulsion polymerization. Also one methyl methacrylate/ methyl α‐chloroacylate/α‐chloroacrylonitrile (MMA/MCA/ ACAN) terpolymer was prepared. The radiation susceptibilities of these terpolymers were measured using the 60Coγ‐irradiation method. Molecular weights were determined both by membrane osmometry and gel permeation chromatography. All terpolymers exhibited higher radiation‐degradation susceptibilities than poly(methyl methacrylate). The Gs values did not follow the general trend, previously observed with MCN/MCA copolymers, of being directly proportional to the respective terpolymer compositions. In some cases, the addition of small quantities of α‐chlorine‐containing monomers caused Gx to increase. This observation greatly differs from those observed for copolymer systems such as MMA/MCA, MCN/MCA, MMA/ ACAN, etc. studied previously. Terpolymerization gives highly soluble polymers especially suitable for wet development by many solvents. This is an important consideration for polymers with high mole fractions of methacrylonitrile (MCN) or vinylidene chloride (VDC) which are rendered soluble in development solvents. The electron‐beam sensitivities were obtained for samples of three classes of the terpolymers and they were higher than that of PMMA. For example, at 20Kev a 62/34/4 MMA/MCN/MCA terpolymer exhibited a sensitivity of 1.3 × 10−5 coulombs cm−2 at l/lo = 1. The introduction of ACAN narrows the working range for positive resist behavior. For example MMA/MCN/ACAN(41/40/19) has a sensitivity of 8.3 × 10−6 coulombs cm−2 at l/l0 = 0.6 but it crosslinks at 1 − 1.3 × 10− coulombs cm2. The MMA/MCN/VDC(21/76/3) polymer was about 25 times more sensitive than PMMA (7 × 10−6 C cm−2 at l/l0=1).
Damping modulus studies of poly(dimethylsiloxane)‐bisphenol‐a‐polycarbonate block copolymers
Authors: Maung W. , Williams H. Leverne 
Published: May 2005

AbstractRandom multiblock copolymers of bisphenol‐A‐polycarbonate and poly(dimethylsiloxane) were hot‐pressed or solvent cast into films which were studied by dynamic mechanical methods over the range 11 to 110 hertz (Hz) and 100 to more than 2200 Hz, respectively. The samples were studied also by differential‐scanning calorimetry. The two phases are separated well in spite of the low‐molecular weights of the blocks. This separation is altered by thermal history and by the solvent medium when solvent casting is used to prepare the films. The damping properties do not vary greatly with frequency. Damping is greatest near the glass‐transition temperatures of the two components. The expansion of the block copolymer with heat appears to be retarded by the polycarbonate phase until the glass transition of that phase is approached.
Polymer molecular‐weight distribution from dynamic melt viscoelasticity
Authors: Wu Souhenc 
Published: May 2005

AbstractA method is developed by which polymer molecular weight and its distribution can be accurately determined by deconvolution of dynamic melt viscoelastic properties in the terminal and plateau zones. The method is illustrated with a series of monodisperse (narrow‐distribution) and polydisperse (broaddistribution) polystyrenes. The Mn, Mw, and Mn/Mw values obtained are in excellent agreement with those determined by light scattering, osmometry and gel permeation chromatography with less than 5 to 10 percent error. The differential molecular‐weight distribution curves obtained coincide wall with those obtained by gel permeation chromatography. The method is applicable to insoluble as well as soluble polymers.
Surface embrittlement of ductile polymers: A fracture mechanics analysis
Authors: Roliand L. , Broutman L. J. 
Published: May 2005

AbstractThe embrittlement of ductile polymers resulting from outdoor weathering or aging or from the application of brittle surface coatings is explained using fracture mechanics principles. It is shown that in order for surface embrittlement to occur, the brittle surface should have a dynamic stress intensity factor at the brittle/ductile interface that exceeds the arrest toughness of the ductile polymer. This phenomenon is modeled using duplex tensile specimens fabricated from poly(methylmethacrylate) (brittle layer) and polycarbonate (ductile substrate) as well as from styrene‐acrylonitrile and acrylonitrile‐butadiene‐styrene copolymers.
Free radical polymerization of methyl methacrylate at high temperatures
Authors: Baillagou Pierre E. , Soong David S. 
Published: May 2005

AbstractFree‐radical polymerization of methyl methacrylate in a tubular reactor has been conducted at above‐Tg temperatures. A salient feature of these experiments is the very efficient control of reactor temperature by vapor‐liquid equilibrium of the polymerizing mixture via monomer evaporation. The system pressure thus provides a powerful control variable, restricting the temperature in the entire reactor by changing the monomer evaporation rate. In the range of our experimental conditions, the temperature and pressure in the reactor follow the Antoine equation closely. High temperature runs also reduce the length requirement of the reactor. However, molecular weight averages of the products are not impressive, unless slow‐burning initiators are used. Modeling of above‐Tg reactions has been attempted at two‐levels of sophistication. A plug‐flow model gives predictions in good agreement with our experimental temperatures and conversion data. The predicted molecular weights are also consistent with the experimentally observed values. However, the more elaborate rheokinctic model suggests that the superficial agreement between model and experiment is due to initiator burn‐out, which limits the final conversion to within 40 percent. The liquid layer next to the reactor wall can never be so viscous as to form a stagnant deposit, due to this conversion limitation. The velocity profiles are thus not very much distorted, and a plug‐flow model is adequate. With a slow‐burning initiator and a sufficiently long reactor, skewing of velocity profile and reactor channeling will eventually emerge. Hence, the rheokinetic model must be evoked to model the system under such conditions.
Shear deformation under impact conditions
Authors: Sjoerdsma S. D. , Boyens J. P. H. , Mooij J. J. 
Published: May 2005

AbstractThe deformation behavior that results from falling weight impact testing with flat‐headed darts is analyzed in terms of elasticity and plasticity. From a comparison of the time and temperature dependence of the yield stress that is observed during a falling weight test with the same dependences of the yield stress during simple shear tests, it is concluded that the use of flat‐headed darts results in strong shear loading. Consequently most of the plastic deformation takes place by shear flow. Of practical interest is that this leads to a simple dependence of the yield stress during the impact test and the impact energy on the plate thickness. Furthermore, for a number of cases this result allows a direct conversion of temperature effects to time effects. In practice this means that it is possible to simulate the impact behavior at very high impact rates simply by performing impact tests at lower temperatures.
Flow of polymeric melts in short tubes
Authors: Isayev A. I. , Chung B. 
Published: May 2005

AbstractIn an attempt to further understand the flow of polymeric melts through gates in injection molding, the present investigation deals with measurement of pressure drops during isothermal extrusion of fiber‐filled and unfilled polystyrene, polypropylene, and polycarbonate melts in short tubes with sudden contraction at high shear rates typical of injection molding. Flow curves for these materials have been determined over a wide range of shear rates at various temperatures by using a capillary rheometer and extruder. Measurements indicate that rheological properties of fiber‐filled melts after injection molding differ from those of fresh samples. Moreover, it has been found that decreasing the tube length increases the slope of the curve for pressure drop vs. Volumetric flow rate. Extra pressure losses due to end effects have been determined which show that at high shear rates these losses can reach levels as high as 100 bar, with the effect being higher for the fiber‐filled melts. By using a viscoelastic consitutive equation, the extra pressure losses have been separated into entrance and exit losses. Model parameters required for this calculation have been determined from viscosity‐shear rate curves for the melts. For various polymers, master curves useful for industrial applications have been constructed for the extra pressure losses.
Influence of the molecular structure on the melt strength and extensibility of polyethylenes
Authors: La Mantia F. P. , Acierno D. 
Published: May 2005

AbstractMelt strength (MS) and breaking stretching ratio (BSR) data relative to polyethylenes with different molecular structure (high density (HDPE), low density (LDPE), and linear low density (LLDPE)) are shown. HDPE and LLDPE samples show high breaking stretching ratio and low melt strength values. The LDPE samples exhibit very large melt strength values but low breaking stretching ratio values. For the last mentioned samples, differences are shown in the non‐isothermal elongational behavior between samples polymerized with tubular and vessel technology. For all the samples, MS decreases with increasing melt index while BSR increases with melt index.