bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of silicon polymer as positive photosensitive material
Authors: Aoai Toshiaki , Umehara Akira , Kamiya Akihiko , Matsuda Nobuaki , Aotani Yoshimasa 
Published: December 2004

AbstractA new positive‐working photosensitive system of silicon polymer, containing silylether groups in the main chain and a photo‐induced acid precursor was investigated. The silicon polymer is hydrolized by a photogenerated acid and degraded to low molecular weight compounds. Thus the effect of solubility inhibition of the polymer is diminished. The higher photosensitivity of this system as compared with 1,2‐quinone diazide compounds is due to the catalytic reaction of the acid on the hydrolysis of the silicon polymer. The chemical structure around silylether groups in the polymer, in particular more hydrophilic and less steric structures, affects the rate of hydrolysis and thus the photosensitivity. Among various types of photo‐induced acid precursors examined, e.g., s‐triazine and 1,3,4‐oxadiazole compounds substituted by trihalomethyl groups were effective.
A sub‐0.5 μm bilevel lithographic process using the deep‐UV electron‐beam resist p(si‐cms)
Authors: Novembre A. E. , Jurek M. J. , Kornblit A. , Reichmanis E. 
Published: December 2004

AbstractOptimization of the deep‐UV and electron‐beam lithographic properties of a copolymer of trimethylsilylmethyl methacrylate (SI) and chloromethylstyrene (CMS), P(SI‐CMS), within a weight average molecular weight range of 1.4 to 4.1 × 105 and 90 to 93 mole percent SI composition has been achieved. The solubility behavior of P(SI‐CMS) resist was examined using the Hansen 3‐dimensional solubility parameter model and dissolution rate measurements. Swelling of the resist has been minimized through the identification of a single component developer (2‐propanol) and rinse (water) system. For the material containing 90 mole percent SI (14.9 weight percent Si) and M̄ω = 1.4 × 105, the sensitivity to 248 nm radiation is 65 mJ/cm2 and to electron‐beam exposure is 3.4 μC/cm2 at 20 kV. This material Is applicable to bilevel lithographic processes, and the O2 reactive ion etching (RIE) rate is 16 times slower than standard hard‐baked photoresist. Using a He/O2(60/40) RIE pattern transfer process, 0.4 μm line/space patterns have been resolved in a 1.3 μm bilayer structure for deep‐UV exposures, and 0.25 μm imaging has been demonstrated in a 0.7 μm thick planarizing layer using electron beam irradiation. The loss in linewidth associated with the 0.25 μm process is ∼0.04 μm.
Soluble and optically transparent fluorine‐containing photoreactive polyimide precursors: Spectral sensitization by organic peroxide and organic dye combination
Authors: Omote T. , Koseki K. , Yamaoka T. 
Published: December 2004

AbstractPhotoreactive polyimide precursors involving the hexafluoropropyl group with chain structure have been developed. These polyimide precursors are readily soluble in common organic solvents and optically transparent for light of 365nm wave length (i‐line) similar to aliphatic polyimide precursors. These precursors offer high resolution patterns with aspect ratio of more than 2.0. In these polyimide precursors, the polymers which have a benzophenone segment in the polymer backbone are self‐sensitized, and show interesting photochemical reactions. The authors have been also tried to extend the range of spectral sensitivity of BPDA‐AMHFP toward longer wavelengths (> 436 nm) by the addition of an organic peroxide (BTTB) and a sensitizing dye selected from coumarine, ketocoumarine, xanthen, etc.
High‐Speed fracture mechanics by photography of polypropylene copolymers
Authors: Bramuzzo M. 
Published: December 2004

AbstractThe use of photography applied to stroboscopy in analyzing the processes inherent to the starting and propagation of cracks in materials is a technique which has proved to be of great interest, especially since it enables one to check and “directly” study the evolution of such phenomena. Using fracture mechanics criteria this technique has been applied to the study of the impact behavior of some polypropylene copolymers at different rubber contents obtained either by blending or by synthesis. This technique makes it possible to determine numerous parameters of fracture mechanics, including C.O.D. (crack opening displacement), C.O.A. (crack opening angle), JIc, the plastic work parameter, determined from the resistance curveR, tearing modulus, and crack propagation velocity. Furthermore, under high strain rate conditions, the value taken on by the coefficient “λ” relating theJ‐integral to C.O.D. (1, 2) were checked for those materials using the equationJ= λ. σy · C.O.D., Hayes and Turner (3) and Boyle (4). From analysis of the materials it was possible to note that the synergetic effect of the EP (ethylenepropylene) rubber increased, especially when present at percentages of more than 10 percent. Annealing the materials, on the other hand, produced an increase in fracture toughness for those products having a low rubber content; however it did not have any effect on those with an elevated rubber content (26 percent).
Ultrasonic velocity and attenuation of polymeric solids under oscillatory deformation: Apparatus and preliminary results
Authors: Tanaka A. , Nitta K. , Onogi S. 
Published: December 2004

AbstractA new apparatus has been constructed in which ultrasonic velocity and attenuation coefficients can be measured under oscillatory deformation. Using this apparatus, dynamic ultrasonic parameters were obtained with sufficient accuracy to investigate plastic deformation directly. It is found that this method has potential as a new tool for the study of solid polymers during deformation.
Evaluation of dynamic density by simultaneous measurement of ultrasonic velocity and elastic modulus under oscillatory deformation
Authors: Nitta K. , Tanaka A. 
Published: December 2004

AbstractIt is proposed that dynamic density can be estimated from simultaneous measurements of ultrasonic velocity and modulus under an oscillatory deformation. An experimental investigation was carried out and a theoretical model applied. Preliminary experiments show that measurement of the dynamic density is a major aid to the study of plastic deformation.
Thermo‐Oxidative aging of a primary lightguide coating in films and dual‐coated fibers
Authors: Simoff D. A. , Chan M. G. , Chapin J. T. , Overton B. J. 
Published: December 2004

AbstractThe thermo‐oxidative aging of a polyether urethane lightguide primary coating has been studied in films and dual‐coated fibers, In films, oxygen absorption is correlated with changes in modulus, yellowness, glass transition temperature, and sample weight. Thermal aging of fibers shows similar trends with regards to coating weight loss and discoloration as those observed with films. In addition, the force to mechanically strip the fiber follows the same patterns of change as the modulus of aged films. For both films and fibers, the time for onset of property changes varies inversely with temperature and can be delayed by the incorporation of an antioxidant.
The dependence of butt fusion bond strength on joining conditions for polyethylene pipe
Authors: Pimputkar S. M. 
Published: December 2004

AbstractThe integrity of a pipeline system is determined by its weakest links. Joints may be such places. Heat fusion is the most common joining method for distribution gas piping. There are procedural, thermal, and mechanical aspects of making fusion joints. Procedural aspects, such as heater calibration and cleanliness, can be assured only by rigorous training and certification of the operators. Thermal and mechanical aspects consist of specifying joining conditions such as the heater temperature, heating time, and joining pressure. In the absence of procedural errors, the strength of a fusion joint should depend on the pipe material, pipe dimensions, and the thermal and mechanical joining conditions.The measured parameters that are measures of strength are impact energy and location of failure in the tensile impact test. A parameter, termed the joining parameter, was found to characterize the joining conditions. This parameter is a function of bead volume, melt volume at the end of the heating phase, and pipe wall thickness. Of the mechanical test parameters, the impact energy was found to correlate best with the joining parameter.
Properties of post‐cured siloxane networks
Authors: Quan X. 
Published: December 2004

AbstractPost‐curing of vinyl‐addition cured siloxane networks can take place due to the presence of excess silicon hydride. The reaction of these groups, which leads to increased crosslink density especially at elevated temperatures, can be retarded by treatment with ammonia gas or eliminated by exposure to ethylene gas. There is an interesting correspondence between post‐curing behavior and the gelation process. In both cases, two curing regimes are observed. For low extents of reaction, the mobility of chains is high, even though the post‐curing experiment is performed on samples which have already gelled, and the cure is controlled by reaction kinetics, not by the diffusion of the reactants. At high degrees of cure or post‐cure, both cases behave as crosslinked networks to reduce the probability of interaction between reactants, and the cure is diffusion‐controlled. However, the post‐cured gels do not exhibit ideal network behavior since the last crosslinks formed during post‐curing have a much greater effect on the physical properties than those formed initially. This may be due to the bimodal distribution of chain lengths between crosslinks that is formed during post‐curing.
Computer vision methods for the study of spinodal decomposition in polymer blends
Authors: Gur Y. S. , Malone M. F. , Bhatia Q. S. , Reynolds G. , Karasz F. E. , Hanson A. R. , Riseman E. M. 
Published: December 2004

AbstractWe demonstrate the use of computer vision techniques and optical microscopy to follow the kinetics and microstructure during spinodal decomposition of a polymer blend. Among other features, the mean of the population of the local maxima of the gradients in each image is computed; this global feature is shown to co‐develop with the phase separation of the blend. An algorithm is presented which employs the gradient magnitude technique to analyze optical images of spinodally decomposing polymer blends. This algorithm has been used to extract the Cahn‐Hilliard spinodal growth rates for a binary blend of polystyrene with poly(vinyl methyl ether). We show that the spinodal temperature can be found from the temperature dependence of this growth rate. We also show how additional shape features such as compactness might be used to study, the same binary blend.
Phase morphology of as‐molded and annealed blends of polyarylate/copolyester
Authors: Plummer H. K. , Peters C. R. , Golovoy A. 
Published: December 2004

AbstractThe phase morphology of injection molded blends of polyarylate (PAR) and a copolyester (PCTG‐5445) was studied by transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The use of ultramicrotomy to prepare ⋍ 50 nm thin section TEM specimens and solvent etching to dissolve the PAR phase revealed PCTG as the matrix phase in the as‐molded state which crystallized into PCTG spherulites upon annealing. The most consistent morphological information vs. concentration of PCTG and the highest structural integrity of the PCTG spherulites was obtained from thin sections treated with a mixture of 75% methylene chloride as the solvent for the PAR and 25% 2‐propanol as the nonreactive diluent. XRD results from the annealed PCTG/PAR blends show crystalline reflections of 0.59, 0.53, 0.46, 0.38, and 0.35 nm, which disappear into the amorphous background below 50% PCTG.
Structure development in biaxially stretched polystyrene film: Part II. Theoretical analysis of orientation development
Authors: Choi Kyung‐Ju , Spruiell Joseph E. , White James L. 
Published: December 2004

AbstractThe present paper describes an analysis of the orientation developed in biaxially stretched polystyrene films in terms of the kinematics of the process and a viscoelastic constitutive equation. It was possible to achieve reasonable agreement of predicted and experimental birefringences through use of a convected Maxwell model and the Rheo‐Optical Law.
The influence of microstructure on the dynamic mechanical behavior of polycarbonate/poly(styrene‐co‐acrylonitrile) blends
Authors: McLaughlin K. W. 
Published: December 2004

AbstractThe influence of microstructure on dynamic mechanical behavior in the two phase blend of polycarbonate, (PC), with poly(styrene‐co‐acrylonitrile), (SAN), was studied by comparing the torsional response for injection and compression molded samples. A matrix component's glass transition (Tg) damping was only moderately altered by the presence of a dispersed phase although shifts in Tg, assigned to the local maxima in tan delta, indicated partial miscibility. In compression molded samples the onset of a co‐continuous PC phase suppressed the damping characteristics of the SAN Tg on the high temperature side shifting the assignment of this Tg to lower temperatures. This suppression results from PC dominating the composite's response at temperatures above the SAN Tg. In injection molded samples the onset of PC co‐continuity only partially suppressed the damping of the SAN Tg such that a doublet results. Co‐continuity within the injection molded microstructure could be idealized as alternating sheets which, subsequently, in the dynamic mechanical measurement are arranged In series to a shearing stress during torsion. Above the Tg of SAN the presence of such a series phase arrangement allows the composite to strain approximately to that extent which would be exhibited by pure SAN alone. The response of the composite is thereby approximately the response of SAN with the almost full extent of its Tg damping process realized.
An energy balance approach to solvent removal in polyamic acid coatings
Authors: Bauer C. L. , Farris R. J. 
Published: December 2004

AbstractUsing an energy balance approach incorporating a Flory‐Huggins expression for free energy and the strain energy of the material, the solvent removal process in liquid‐based coatings was shown to depend on stress and temperature. An equilibrium is obtained between residual solvent content and stress in the coating at a given temperature. Such stress‐dependent solvent removal behavior was observed with a polyamic acid coating solution‐cast using N‐methylpyrrolidinone.
New results on the spin welding of plastics
Authors: Tappe P. , Potente H. 
Published: December 2004

AbstractShort welding times make spin welding particularly suitable for mass production. This paper presents an analysis of the friction phase, which makes it possible to estimate the influence of the welding parameters and the material being welded on the temperature in the welded zone, the melt rate, and the torque in the spin welding of semicrystalline thermoplastics. A comparison of experimental and calculated results shows an acceptable correlation. In addition, the influence of speed, axial pressure, and braking on the weld seam quality of different amorphous and semicrystalline thermoplastics is discussed.
Water sorption and hydrolytic stability of polycarbonates
Authors: Golovoy A. , Zinbo M. 
Published: December 2004

AbstractThe hydrolytic stability of a new commercial polycarbonate (Calibre 300, Dow Chemical USA) was investigated and compared with that of other commercial polycarbonates. The tests were conducted between 56% and 95% relative humidity (R. H.) at 100°C. Also performed were water immersion tests at 80 and 100°C. The water diffusivity was found to be 8.7 × 10−7 cm2/s at 100°C with an activation energy of 7.9 kcal/mole. These values are similar to other glassy polymers. The equilibrium water sorption, C∞, was found to increase with temperature and R.H. The isotherm at 100°C was determined to be: C∞ = 0.005945 [R.H.]. When samples immersed in a water bath at 100°C were transferred into room‐temperature water, visible aqueous microcavities were formed due to the condition of super‐saturation, and under stress may become crack initiation sites. For the polycarbonate investigated here, it was found that the decrease in weight‐average molecular weight (M̄)w was a first‐order process under a constant R.H. and temperature, and that hydrolytic embrittlement, i. e., (M̄)w <34,000, was reached after ca. 188, 143, 99, and 66 days under 56%, 73%, 87%, and 95% R.H., respectively, at 100°C. A comparison with reported hydrolytic stability data for other polycarbonates showed large differences in their stability which are believed to be due to the extent of end‐group capping (over 95% in Calibre 300) and resin purity: both phenolic end‐groups and some additives (i.e., fire retardants, thermal stabilizers) are known to accelerate hydrolytic degradation.
Solution of mass transfer in step growth polymerization in films with bulk in equilibrium
Authors: Khanna Ashok , Kumar Anil 
Published: December 2004

AbstractWe have analyzed step growth polymerization in a flat film with finite mass transfer resistance. We have shown rigorously that the molecular weight distribution (MWD) at equilibrium is given by the Flory distribution, and under reaction the form of the MWD does not change if the feed is either pure monomer or in equilibrium initially. Extensive computations have shown that it is possible to split the film into growing interfacial and shrinking bulk regions. It is possible to obtain similarity transformations of concentrations of condensation product, and polymer as time invariant profiles. Based on this finding, we have determined a solution for step growth polymerization with finite mass transfer in films. The results lie within 5% of the “exact” numerical computations, for all possible variations of parameters.
Heat capacity of polypropylene composite at high pressure and temperature
Authors: Hsieh K. H. , Wang Y. Z. 
Published: December 2004

AbstractThe heat capacities of isotactic polypropylene and its composite with glass fiber have been measured at high pressure, up to 7 MPa, in the melt state by high pressure differential scanning calorimetry (HPDSC). The values also have been calculated from the data of specific volume (V) measured by dilatometry and thermal conductivity (κ) and thermal diffusivity (α) measured by a compensating hot wire method. The values of the heat capacity measured from HPDSC are consistent with those from the calculation method. The heat capacities of molten polypropylene and its composite increase linearly with temperature at a constant pressure and decrease with pressure at a constant temperature. It was found that the heat capacity of polypropylene is insensitive to molecular weight. The heat capacities of molten polypropylene composites are found to be predicted by an additive rule from the weight fractions of heat capacities of polypropylene and glass fiber.
Bulk density of solid polymer resins as a function of temperature and pressure
Authors: Hyun Kun S. , Spalding Mark A. 
Published: December 2004

AbstractIn a plasticating extruder, solid polymers are heated and are subjected to high pressures before they are melted and delivered to a die. In both the solids conveying and melting sections, these temperature and pressure increases will compact the unmelted polymer bed as it moves down the screw channel. Performance of the extruder depends in part on how well the screw design matches the compaction behavior of the resin for a given set of process conditions. The design of these screw sections, however, is often done based on past experience and with little knowledge of the resin compaction behavior. A much improved design would include screw performance prediction using variable bulk density and computer simulations. Computer simulations, however, are often performed using constant solid bulk density because of the lack of reliable density data as a function of both pressure and temperature. An instrument was developed for studying the compaction behavior of pellet and powder resins. Bulk densities and storage friction coefficients are reported for several important thermoplastic resins as a function of temperature and pressure. The bulk density data were fitted to a semi‐empirical model.
A modified power law model for the steady shear viscosity of polystyrene melts
Authors: Campbell Gregory A. , Adams Mary Elizabeth 
Published: December 2004

AbstractAn engineering equation that describes the steady shear viscosity of polystyrene melts is developed as an extension of the well known power law model for non‐Newtonian viscosity. The parameters in the equation have been related to weight and number averaged molecular weights and temperature. The model is tested on data for both narrow and broad molecular weight polystyrenes whose properties span most materials of commercial importance. This equation predicts the melt viscosity‐shear rate behavior for both narrow and broad distribution polystyrenes from knowledge of weight and number averaged molecular weights and temperature. Our analysis directly yields shift factors for the shear rate and viscosity axes. Therefore, no secondary calculations are necessary to generate master curves for polystyrenes. The shift factors are related to weight and number averaged molecular weights of the polystyrenes and temperature of the melt.
Reaction injection molding of polyureas. II: Rheo‐kinetic changes and model simulation
Authors: Wang K. J. , Huang Y. J. , Lee L. James 
Published: December 2004

AbstractAn experimental and theoretical study of reaction injection molding (RIM) of polyurea was conducted in this work. A lab‐scale RIM machine was used to carry out the polyurea bulk polymerizations. A “free‐table” viscometer was designed to measure the fast rheological changes and liquid‐solid transition. A mathematical model was proposed to simulate the fast reaction and rheological changes in the polyurea RIM process. The parameters of this model were determined based on the solution polymerization data from FTIR and Haake rheometer measurements. Combined with an appropriate heat transfer equation, this model predicts fairly well the adiabatic temperature and viscosity rises of bulk polyurea reactions in RIM.