bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oriented structure formation during polymer film extrusion
Authors: Sakellarides S. L. , McHugh A. J. 
Published: December 2004

AbstractAn experimental technique is described for producing fiberreinforced polymer films by inserting needle‐like obstructions in a film‐extrusion die. The, needles act as nucleation sites, generating a highly extensional local flow field, which causes sufficient orientation to induce the formation of oriented fibrillar crystallites embedded in a much less oriented matrix. To study the effectiveness of the above technique, linear low density polyethylene (LLDPE) and blends of linear low density with high density polyethylene (HDPE) were extruded through a film die with converging walls, with one or five needles inserted parallel to the extrusion direction, Microscopy observations, birefringence, and differential scanning calorimetry (DSC) measurements performed on the produced films showed in all cases that the presence of the needle induced the formation of a more oriented phase, which in most cases had a birefringence at least an order of magnitude higher than the film matrix. The best results were obtained in the case when blends of HDPE and LLDPE were extruded. The oriented structures obtained in this case consisted of HDPE and exhibited not only high birefringence but melting point elevation as well, indicating their fibrous nature.
Characterization of crystallinity, orientation, and mechanical properties in biaxially stretched poly(p‐phenylene sulfide) films
Authors: Maemura Eiji , Cakmak Mukerrem , White James L. 
Published: December 2004

AbstractIn this paper, we describe the preparation and structural characterization of biaxially oriented poly(p‐phenylene sulfide) (PPS) films. These films were prepared in a biaxial stretching machine at various stretching temperatures, rates, and stretching ratios. Selected samples were constrained annealed at elevated temperatures. The state of orientation was determined by wide angle X‐ray diffraction (pole figure determination) and birefringence measurements. The results are expressed in terms of the biaxial orientation functions (ƒ,ƒ). Mechanical properties (tensile modulus, tensile strength, and elongation to break) were obtained as a function of processing conditions and direction in the plane of the films.
The effect of hot drawing on the properties of thermotropic polymer fibers
Authors: Dibenedetto A. T. , Nicolais L. , Amendola E. , Carfagna C. , Nobile M. R. 
Published: December 2004

AbstractThermotropic liquid crystal polymers have been modeled as an array of highly ordered polyhedric nematic domains immersed in a less‐ordered, nearly isotropic matrix. A function has been defined that expresses the elastic moduli of drawn fibers as a function of orientation and geometry of the nematic domains. When such a material is hot drawn in extension, the domains orient and elongate to produce an orthotropic fibrous phase. Equations are proposed to relate the elastic moduli of the fibers to the draw ratio and the extrusion conditions. Upon annealing of the hot drawn fibers, shrinkage occurs. It is proposed that the shrinkage is the result of a physical transformation from the fibrous state back to the nematic domain structure present before extrusion and drawing. The Avrami equation is used to describe the nucleation and growth processes controlling the shrinkage at constant annealing temperature. The model is shown to correlate experimental data on the elastic properties and the shrinkage of hot drawn PET/PHB60 liquid crystal polymer with the processing conditions.
Relationship between electron sensitivity and chemical structures of polymers as electron beam resists. VI: Electron sensitivity of various acetalized poly(vinyl alcohol)s
Authors: Oguchi Kiyoshi , Sanui Kohei , Ogata Naoya , Takahashi Yoichi , Nakada Tomihiro 
Published: December 2004

AbstractAcetalized poly(vinyl alcohol)s which were synthesized from poly(vinyl alcohol) (PVA) and aldehyde or ketone were evaluated as electron beam (EB) resists, in order to investigate the relationship between EB sensitivity and chemical structures of the polymers. It was found that the acetalized PVAs were easily crosslinked by EB exposure. The main mechanism of crosslinking may be radical reaction at acetal group. The sensitivity of the acetalized PVA depended on the structure of the acetal group. Acetalized PVAs synthesized from benzaldehyde, in which the electron attracting group was substituted on the benzene ring and from linear aliphatic aldehyde having a long alkyl chain, had high sensitivity. A high sensitivity of 7.2 × 10−7 C/cm2 was attained when the acetalized PVA synthesized from p‐chloro‐benzaldehyde was used. Acetalized PVAs synthesized from PVA and aldehyde having a cyclic structure had an excellent dry etching durability and were suitable as negative EB resists.
Chemistry of the ternary blends of poly(ethylene terephthalate), bisphenol‐a‐polycarbonate, and polypropylene
Authors: Halder R. S. , Misra A. , Deopura B. L. 
Published: December 2004

AbstractPoly(ethylene terephthalate) (PET) and bisphenol‐a‐polycarbonate (PC) are known to form a miscible blend whereas ternary blends of PET, PC, and polypropylene (PP) form two phases. This is based on the considerations of various chemical events which may occur in these systems. The role of ester‐carbonate interchange reactions during melt mixing and fabricating is found to be unimportant. Differential scanning calorimetric analysis of the ternary blends shows that there appears to occur an exothermic transition in the heating mode of the instrument. This exothermic event was found to be suppressed considerably by incorporating suitable additives into the system. Degradation reactions studied by thermogravimetric analysis and a dilute solution viscometric technique reveal that there exists some kind of interaction among the components even with the immiscible PP component.
Structure‐Property‐Processing relationships of polyurethane‐polyester interpenetrating polymer networks
Authors: Wang K. J. , Hsu T. Jeffrey , Lee L. James 
Published: December 2004

AbstractInterpenetrating polymer networks of polyurethane and unsaturated polyester were prepared by reaction injection molding (RIM) and transfer molding. The structures of the molded samples were analyzed by electron microscopy and dynamic mechanical analysis. It was found that polymer morphology and dynamic mechanical properties depend strongly on the molding temperature, reaction rate and reaction sequence. Simplified structure models based on Takayanagi's model and sample morphology can predict the storage modulus reasonably well but not the tanδ.
Pumping characteristics of self‐wiping twin‐screw extruders—A theoretical and experimental study on biopolymer extrusion
Authors: Lai‐Fook R. A. , Senouci A. , Smith A. C. , Isherwood D. P. 
Published: December 2004

AbstractThe flow of Newtonian and non‐Newtonian fluids which obeys a power law relationship between shear stress and shear rate has been modeled in the melt conveying section of a self‐wiping co‐rotating twin‐screw extruder using a finite element analysis of an unwound channel section. Predictions of throughput against pressure gradient are compared with experimentally obtained results for maize grits which is represented as a power law material. Rheological data applicable to extrusion simulation were obtained from capillary rheometry. Comparisons are reasonable with predicted characteristic showing similar behavior.
On the increase of viscoelastic modulus with advancement of reaction of an epoxy resin
Authors: Serrano D. , Harran D. 
Published: December 2004

AbstractLog G* = f(X) isothermal variation curves were determined at various temperatures for two epoxy‐aromatic amine systems widely used in industry. G* = G′ + jG″ is the viscoelastic modulus, determined by sinusoidal shearing at constant frequency between parallel plates; X represents the degree of reaction, determined by calorimetry. These curves clearly show the phenomena of gelation and glass transition. In the temperature range studied, the value of X at the gel point varies between 0.7 and 0.9 for the DGEBA‐DDS system, and from 0.3 to 0.8 for the TGDDM‐DDS system. These variations reflect a major modification of the reaction mechanism, particularly before the gel point.
Evaluation of surface treatments for glass fibers in composite materials
Authors: Dibenedetto A. T. , Lex P. J. 
Published: December 2004

AbstractThe thermomechanical stability of a number of organosilane surface treatments for glass fibers was evaluated for use in a fiber reinforced epoxy resin. All of the silane coatings were found to improve the tensile strength of E‐glass filaments, particularly at large gauge lengths. A phenylamino silane and an amino silane were particularly effective in this regard. The fiber/matrix interface was evaluated as a function of temperature and after exposure to boiling water using a single‐fiber composite test. All silane coatings transmitted a higher interfacial shear stress than obtained in composites with no coatings, and in all cases the shear stress transmission was considerably higher than would be expected from the yield properties of the resin. Measurements of the glass transition temperature of the epoxy resin, as well as Fourier‐Transform Infra‐Red analysis, indicated modification of resin properties in a zone around the glass fibers. Each of the silane coatings provided more stable thermomechanical properties than those obtained with uncoated glass, at least until the silanes were irreversibly degraded by boiling water. A phenylamino silane provided the most thermally stable properties. Finally, unidirectional E‐glass fiber reinforced laminae were fabricated and the measured values of longitudinal strength were compared favorably to theoretical predictions.
Surface structure, topology, and liquid wetting behavior in oriented polymers
Authors: Sung N. H. , Lee H. Y. , Yuan P. , Sung C. S. P. 
Published: December 2004

AbstractThe structure and the properties of oriented polymer surfaces were studied for three series of uniaxially oriented films of polypropylene (PP), polystyrene (PS), and poly(ethylene terephthalate) (PET). The surface structure was characterized in terms of relative crystallinity and molecular orientation along with topology and roughness by using FT‐IR‐ATR dichroism technique, optical microscopy and surface profilometer. In all three polymers, the surface orientation function increases with draw ratio. The relative surface crystallinity and the trans con‐former also increases for PP and PET, respectively. In uniaxially drawn PP, the surface becomes rough with increasing draw ratio and the roughness is anisotropic with peaks and valleys elongated along the draw direction. For drawn PP, the equilibrium contact angles for four different liquids all exhibit anisotropy with higher values in perpendicular direction than that in parallel to the draw direction. In contrast, both drawn PET and PS films show smooth surfaces, and the equilibrium contact angles were all isotropic. When roughness is removed from the drawn PP by polishing without altering the molecular orientation, the anisotropy becomes negligible and the contact angles approach the value for undrawn PP. When surface roughness was created deliberately on undrawn PET and PS films, the contact angle anisotropy was clearly observed. Therefore, the anisotropy in surface topology rather than the molecular orientation seems to play a dominant role in developing anisotropic wetting behavior. The equilibrium contact angles for smooth surfaces have been calculated using the experimentally obtained roughness and anisotropic contact angle data from the rough surface. These values are in reasonable agreement with the measured contact angles for smooth surfaces, suggesting that the observed contact angle anisotropy can be attributed entirely to the roughness anisotropy rather than to the molecular orientation.
Elastomeric latex domain‐interpenetrating polymer networks: Physical and rheological properties
Authors: Silverstein M. S. , Narkis M. 
Published: December 2004

AbstractThe combination of rubbery and rigid polymers in a multiphase structure using staged emulsion polymerization has yielded materials with properties ranging from reinforced elastomers to high impact plastics. The many different particle morphologies that result from a two‐stage latex (TSL) polymerization include core/shell, domain, interpenetrating polymer networks (IPN), and various combinations thereof. The sequence of polymerization, crosslinking, grafting, and composition are among the significant parameters that determine the particle morphology. Elastomeric TSL with soft polyacrylates (PA) as the seed particles and polystyrene (PS) as the second stage, with each stage lightly crosslinked, may yield IPN‐microdomain particles.The particle morphology has been elucidated through a combination of microscopy and mechanical property analyses. The significant modulus of elastomeric latex interpenetrating polymer networks (LIPN) results from reinforcement by PS intra‐particle microdomains and their significant tensile strength from a strength forming mechanism of PS inter‐particle microdomains. The increase in the PA seed crosslinking increases the crosslinked PS (xPS) level of molecular mixing with, and grafting via residual unsaturation to, the crosslinked PA (xPA) network and decreases particle deformnability. At higher xPS concentrations the formation of an xPS‐rich shell enhances xPS continuity in the molded material through the partial coalescence of the shells, diminishing the PA continuity, and yielding more PS‐like properties.The submicron lightly crosslinked latex particles with these different morphologies flow as a pseudoplastie material through a particle slippage flow mechanism exhibiting neither a Newtonian plateau nor a yield stress at low shear rates. The deformable lightly crosslinked particles with interchangeable PS ties which disintegrate at elevated temperatures retain their identity and regain their shape at the cessation of shear. The LIPN can be processed using standard thermoplastic methods and machinery, with power law constants and shear insensitive flow activation energies that are similar to those of thermoplastics at high levels of shear. Uncrosslinked PS shells around crosslinked PA seed particles, on the other hand, completely coalesce upon molding to form a continuous thermoplastic PS matrix that may essentially flow through molecular deformation.
Positive excimer laser resists prepared with aliphatic diazoketones
Authors: Sugiyama Hisashi , Ebata Keisuke , Mizushima Akiko , Nate Kazuo 
Published: December 2004

AbstractA new class of alkali‐developable positive excimer laser (KrF) resists is described. Novel α‐diazoacetoacetates derived from aliphatic polyfunctional alcohols were synthesized. These compounds undergo photolysis upon deep UV exposure to yield carboxylic acids, and exhibit excellent bleaching effects. Some of them, especially those having steroid skeletons, act as effective dissolution inhibitors. The composites prepared from these compounds and poly(p‐hydroxybenzylsilsesquioxane) were used as alkali‐developable positive deep UV resists, whose sensitivities depend on the number of photoactive groups in one photoactive molecule. Imaging results of KrF excimer laser projection printing are presented.
Polysilanes: Photochemistry and deep UV lithography
Authors: Miller R. D. , Wallraff G. , Clecak N. , Sooriyakumaran R. , Michl J. , Karatsu T. , McKinley A. J. , Klingensmith K. A. , Downing J. 
Published: December 2004

AbstractThe photochemistry of poly(cyclohexylmethylsilane) (PCHMS) has been studied, and PCHMS homopolymer has been shown to be useful for high resolution, deep UV pattern generation either by using a commercial 1:1 projection printer operating in the deep UV or by an excimer laser stepper at 248 nm. In the case of the excimer laser stepper, images 0.5 μm and smaller have been printed, which represents an improvement over the 0.8 μm limit previously reported for polysilane copolymers.
A new contrast enhanced lithography (cel) process using “chinese rosin” as a binder
Authors: Tomo Yoichi , Jinbo Hideyuki , Yamashita Yoshio , Ohno Seigo , Asano Takateru , Nishibu Satoshi , Umehara Hiroshi 
Published: December 2004

AbstractA new contrast enhanced lithography (CEL) process using Chinese rosin as a binder is described. This binder is soluble in both non‐polar organic solvent and aqueous alkaline solution. Good coatability with organic solvent, no formation of mixing layer, and direct development without removing the CEL layer are the major advantages of this process. Among the three different kinds of photobleachable dyes, DZ‐2 (diazonium salt) has the best optical property and the resist profile is improved on g‐line reduction projection printing at the smallest dose. Moreover, this DZ‐2—Chinese rosin system is also effective at 365 nm, and the resist profile and the focus margin are improved on i‐line reduction projection printing by using this system.
Synthesis and characterization of positive photosensitive polyimide precursors
Authors: Kubota Shigeru , Yamawaki Youko , Moriwaki Toshimoto , Eto Shohei 
Published: December 2004

AbstractThis paper is concerned with the study of the positive photosensitive polyimide precursors, and deals with monomer synthesis, polymerization, and characterization. The polymers were prepared from diamines and diaeid chlorides whieh were derived from the reactant with biphenyltetracarboxilic dianhydride and o‐nitrobenzyl alcohol. The molecular weights of the polymer were controlled by adjusting the monomer stoichiometry. The photoreaction of the polymers was confirmed from the change in IR spectra between the film exposed and unexposed to UV light from a HgXe lamp. The exposed areas of the film dissolved in alkaline solution, forming the positive tones. There was a marked difference in sensitivity between the polymers having different molecular weights. Their sensitivities decrease as their molecular weights increase. Further, there was a difference in the thermal behavior. Imidization temperature was shifted to a high temperature side and thermal stabilities increased with an increase in molecular weight.
Photochemical image enhancement for 0.5 μm g‐line lithography
Authors: Sheats James R. 
Published: December 2004

AbstractMaterials and processing are described that provide 0.5 μm resolution with between 1 and 2 μm total depth of focus using a 436 nm stepper with 0.42 N.A., using the previously described PIE process (SPIE 631, 171 (1986)); 0.4 μm lines, spaces, and line/space gratings were reproduced. The chemistry is based on the photobleaching of anthracene derivatives in the presence of oxygen, followed by a deep‐UV pattern transfer exposure under nitrogen. Although resolution and process control are quite good, the exposure time of 1.2 s is somewhat long due to the limited oxygen permeability of the chosen polymer; in addition the strong unbleachable absorbance of the deep‐UV resist limits the usable thickness to ∼500 nm. Materials have been identified that promise to overcome both limitations, yielding thicknesses of 1 μm or more and exposure times less than 500 ms. Application to 365 and 248 nm imaging is also possible.
An experimental study of distributive mixing in fully intermeshing, co‐rotating twin screw extruders
Authors: Kalyon Dilhan M. , Sangani Harish N. 
Published: December 2004

AbstractCo‐rotating twin screw extruders are widely used for various mixing and reactive extrusion tasks in polymer processing operations. In this study, the prevailing mixing mechanisms of various screw elements employed in co‐rotating twin screw extrusion process, including regular flighted, and reverse and forward kneading disc elements, were experimentally investigated. A direct goodness of mixing technique based on pigmented thermoplastic elastomers and computerized image analysis was used. The results were elucidated in conjunction with mixing indices suitable for image analysis and the continuous mixing process. Significant differences in the distributive mixing characteristics of various screw elements were revealed.
Shear‐Induced orientation in liquid crystalline polymers
Authors: Kenig S. 
Published: December 2004

AbstractThe orientation development characteristics in shear flow of wholly aromatic thermotropic liquid crystalline polymers were studied. Based on the analysis of shear flow in a capillary followed by elongational flow, an experimental setup has been proposed to determine the shear‐induced orientation. Experimental results have indicated that shear‐induced orientation depends on total shear strain. However, orientation enhancement due to shear flow is much less effective compared with orientation buildup in the case of elongational flow. Thermotropic liquid crystalline polymers that exhibited higher orientability in elongational flow exhibited also higher orientability in shear flow. Finally, to obtain high, shear orientation in processing of thermotropics, special care should be exercised in the design of dies and molds and in optimizing processing conditions, so that high shear rates and/or long shearing times should prevail.
How coating/polymer properties affect fiber/cable performance
Authors: Skutnik Bolesh J. 
Published: December 2004

AbstractThe selection of the coatings/polymers used to fabricate optical fibers has been shown to be very important in determining their optical, mechanical, and connectorization performance. Material properties such as refractive index, optical transmission, and thermal coefficient of linear expansion are critical for coatings functioning as cladding materials. Coating adhesion to the glass surface, water absorption and water vapor permeation, as well as the ability to passivate the glass surface, have strong affects on the strength and fatigue behavior of fibers. Hard, thin, adhesive primary coatings are beneficial in making connectorization easier and more reliable.Many of the preferred properties for the fiber coating are different from those preferred for electrical wire, not only because light must be transmitted rather than electricity, but also because of the brittle nature of the silica substrate and the coupling between physical displacements and light transmission within the guiding material (microbend effects).The selection of cable materials is quite similar to that employed in the electrical wire and cable field. Much more attention must be given to cable design than for the latter. Designs/applications requiring tight jacketed or filled cables put special constraints on the selection of materials for the optical cables, which are more restrictive than for electrical cables.
The effect of temperature dependent materials properties on fiber optic cable design
Authors: Grant Susan C. , Zimmermann Bernd D. , Coupe Kelly L. 
Published: December 2004

AbstractYoung's Modulus and the thermal expansion coefficient are material parameters used to predict the low temperature contraction of a fiber optic cable. In the past, room temperature values for these properties were used to estimate this contraction. In this paper, these properties have been determined as functions of temperature. Using these properties, the overall expansion coefficient of the cable was determined as a function of temperature. This overall coefficient was integrated from room temperature to the low operating temperature of the cable to predict the contraction of the cable. In this way, the temperature variations in the materials properties were incorporated into the design, resulting in a more accurate determination of the low temperature contraction of fiber optic cable.