bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of phase morphology in incompatible polymer blends during mixing and its variation in extrusion
Authors: Min Kyonsuku , White James L. , Fellers John F. 
Published: December 2004

AbstractAn experimental study of the development of phase morphology in incompatible polymer melt blends of polyethylene/polystyrene (PE/PS), polyethylene/polycarbonate (PE/PC), and polyethylene/nylon‐6 (PE/N6) is presented. Different temperatures (180°C, 240°C) of mixing and polyethylene molecular‐ weight levels were used in the PE/PS studies. Little variation in the cross‐sectional phase morphology of the PE/PS extrudates was observed with these variables, though the morphology became finer with increased shear rate/stress in capillary die flow. Variations in the longitudinal morphology are observed with continuous filaments of dispersed phase only arising when the dispersed phase has an equal or lower viscosity than the continuous phase. The PE/N6 and PE/PC, especially the former, give coarser morphologies when the N6 and PC are the continuous phases. This was attributed to larger inter‐facial tensions. The effect of viscoelasticity was also discussed.
A basic study of orientation in poly(ethylene terephthalate) stretch‐blow molded bottles
Authors: Cakmak Mukerrem , Spruiell Joseph E. , White James L. 
Published: December 2004

AbstractA series of stretch‐blow molded poly(ethylene terephthalate) bottles were investigated using measurements of birefringences (in plane and out of plane) and wide angle x‐ray diffraction (WAXS) pole figures. Both bottles prepared in our laboratories and commercial bottles were investigated. Birefringences Δn13 and Δn23 of inside and outside surfaces of bottles were determined as a function of position along the length of the bottle (1‐bottle axis, 2‐hoop direction, 3‐thickness direction). The Δn13, Δn23 for the inside surface of the bottles were found to be greater than those for the outside surface indicating heterogeneity through the thickness of the bottles. The WAXS studies indicate that the benzene rings in the polymer align parallel to the bottle surface. The chain axis in crystalline regions exhibit orientations close to equal biaxial orientation. Both Δn13 and Δn23 increased with inflation pressure.
Predicting water diffusivity in elastomers
Authors: Aminabhavi Tejraj M. , Thomas Richard W. , Cassidy Patrick E. 
Published: December 2004

AbstractBy the use of water absorption data (rate and equilibrium), the diffusivity of distilled and salt water through Neoprene, styrene‐butadiene, and ethylene‐propylene‐diene elastomers was predicted. Activation parameters were calculated from the Arrhenius plots and were used to calculate heats of solution (all negative). Solubility coefficients (S) were calculated from permeability (P) and diffusion (D) coefficients. For all materials salt water showed a lowerDthan distilled water but a higherSandP.
Polycarbonate resins
Authors: Clagett Donald C. , Shafer Sheldon J. 
Published: December 2004

AbstractAn outline of the history and manufacture of polycarbonate resins is followed by a discussion about resin product types anal their processing. The key properties of flex modulus, deflection temperature, and impact are those that make polycarbonate resins premier engineering resins. Like most other engineering plastics, polycarbonate resins' early commercial history was characterized by substitutions of polycarbonate resins for traditional materials, particularly metal and glass. Examples of applications are presented, More recently application developments involve ab initio selection of polycarbonate resins and article designs based on polycarbonate resin properties. In addition, “tailored” resins such as poly (estercarbonate) resins and polycarbonate resin blends have evolved to meet specific applications. The future growth of polycarbonate resins is predicted to feature few new resins, many new blends, and application developments using computer techniques.
Victrex® poly(ethersulfone) (PES) and Victrex® poly(etheretherketone) (PEEK)
Authors: Searle O. B. , Pfeiffer R. H. 
Published: December 2004

AbstractProperties of two high performance engineering thermoplastics, amorphous polyethersulfone (PES) and semicrystalline polyetheretherketone (PEEK), are discussed. Both resins can be processed by conventional techniques, compounded with high performance fibers, and have high service temperature (up to 300°C). Due to the amorphous character PES can be dissolved and spray coated into metals.
Optimal thermal design of injection molds for filled thermosets
Authors: Barone M. R. , Caulk D. A. 
Published: December 2004

AbstractSince the cure rate of injection molded thermosets is usually very sensitive to cavity surface temperature, spatial variations in these temperatures can lengthen the necessary cure time for the entire part and cause distortion and residual stress in the molded article. This problem is addressed in the present paper by combining an optimization algorithm with a quasi‐steady heat conduction analysis in the mold to determine the heating line positions and operating temperatures that minimize the spatial variation in cavity surface temperature. The method is applied to an example mold for a flat panel of uniform thickness, using two different gate locations. At a one‐minute cycle, the optimal designs for each gate location dramatically reduce the variation in cavity surface temperature compared with corresponding results using a conventional heating system. These results are made more significant by the fact that the optimal designs use considerably fewer heating lines. In spite of their simplicity, the optimal designs still have enough flexibility to adjust to a changing cycle without sacrificing uniformity in cavity surface temperature.
Binders for jute‐reinforced unsaturated polyester resin
Authors: Semsarzadeh Mohammad A. , Amiri Davod 
Published: December 2004

AbstractReinforcement of polyester resin with jute cloth under constant load is studied, The pretreatment of jute cloth with tetrahydrofuran and the effect of binding properties of poly(vinyl acetate) and acrylic acid and their effect on the impact, tensile, and water absorptions of jute cloth polyester composites are reported and their chemical reactions are discussed.
Exit pressure effects in capillary die data
Authors: Carreau Pierre J. , Choplin Lionel , Clermont Jean‐Robert 
Published: December 2004

AbstractThe exit flow from a capillary is analyzed with the help of macroscopic mechanical energy and momentum balances. The analysis shows that primary normal stress differences cannot be determined from the exit pressures under the assumption that the flow is viscometric down to the exit. This assumption and the second one (made by Han [9]) that both slit and capillary exit pressures are the same would lead to unacceptable results. Published exit pressure data for polyethylene melts are shown to be unreliable because of large hole‐pressure errors in the pressure measurements. Pressure profiles obtained with a thin tube technique for the flow of a poly(isobutylene) solution indicate that the flow does not remain fully developed near the exit. Moreover, it is shown that for this polymer solution the excess viscous dissipation at the exit contributes to approximately 90 percent of the exit pressure.
The effect of powder particle fusion on the mechanical properties of ultra‐high molecular weight polyethylene
Authors: Zachariades Anagnostis E. 
Published: December 2004

AbstractRheo‐optical and mechanical property studies with compression molded ultra‐high molecular weight polyethylene specimens at different temperatures indicate that their mechanical performance is dependent on the degree of fusion of the powder particles during compression and can be enhanced by heating the polymer powder at temperatures above 220°C. Although the mechanical performance of the compression molded specimens can be improved further by solid‐state drawing at a draw ratio 5, the anisotropic morphologies from molded specimen above 220°C have higher initial slope of stress to elongation, strength to break, and an outstanding elastic recovery in compreision to the compression molded specimens at 180°C.
Effect of surface treatments on rheological, mechanical and magnetic properties of ferrite‐filled polymeric systems
Authors: Saini D. R. , Shenoy A. V. , Nadkarni V. M. 
Published: December 2004

AbstractExperimental data on the effect of the type and amount of surface treating agents on the rheological and mechanical properties of the ferrite‐filled styrene‐isoprene‐styrene systems at high levels of loading has been presented. The viscosities of the treated ferrite systems are found to be lower than the untreated systems, with the extent in reduction depending upon the type and amount of surface treatment. It is also found that surface treatment decreases the tensile strength and percentage elongation in the present filler‐matrix system, and the extent of the decrease in viscosity as well as mechanical properties is more in the presence of titanates than with silanes.
Prediction of axial and off‐axis yield behavior of lsotactic polypropylene film from structural state parameters
Authors: Linder Barbara E. , Samuels Robert J. 
Published: December 2004

AbstractSince only minor structural rearrangements occur prior to yielding, the axial and off‐axis yield stress of a polymer sample is expected to relate to the initial structural state of the material. Samples of uniaxially oriented isotactic polypropylene films with known structural state parameters have been deformed under a uniaxial tensile stress at deformation rates of 20 percent and 100 percent per minute over an angular range from 0 to 90 degrees to the fabrication direction. The axial yield stress data was found to correlate with the initial noncrystalline orientation state of the undeformed sample. The axial and offaxis yield stress data was fit to the Hill equation derived for the application of a uniaxial tensile stress. The experimentally determined coefficients from the best fit of the yield stress data to the Hill equation were related to the measured structural state parameters. These correlations allow prediction of the yield stress of an anisotropic film at any angle to the film symmetry axis from knowledge of the measured structural state parameters alone.
Shear and extensional flow of reinforced plastics in injection molding. I. Effects of temperature and shear rate with bulk molding compound
Authors: Gibson A. G. , Williamson G. A. 
Published: December 2004

AbstractCapillary flow studies on bulk molding compound (BMC) using an instrumented injection‐molding machine are reported. The significance of extensional flow effects with fiber‐reinforced materials is emphasized. The extensional flow behavior in converging dies is modeled, and a means of evaluating both extensional and shear viscosity from capillary flow data is proposed. Methods of correcting results for the effect of deformation heating are discussed. The shear and extensional flow behavior of BMC in the temperature region 18 to 58°C can be fitted to a simplified Arrhenius Law.
Temperature dependence of the thermal expansivity in polymer
Authors: Cho Bongkee 
Published: December 2004

AbstractThe effects of temperature on the specific volumes and thermal expansivities for a range of amorphous polymers, above and below the glass transition temperature, are treated on the basis of the physical properties of polymers. The results are found to be in good agreement with observed data. The analysis of the results shows that the temperature derivative of the zeropressure thermal expansivity of the liquid polymer increases with increasing temperature. The change in the thermal expansivity, Δα = αOL − αOG, decreases with increasing temperature.
Polyvinyl alcohol‐copper II complex: Characterization and practical applications
Authors: Godard P. , Wertz J. L. , Biebuyck J. J. , Mercier J. P. 
Published: December 2004

AbstractA method to obtain microscopic and macroscopic coatings with improved resistance to debonding is described. The procedure, based on polymer‐metal complexes, involved the adsorption on inorganic substrates of a poly(vinyl alcohol)‐copper II chelate that is also able to catalyze the polymerization of monomers or prepolymers with grafting. The molecular structure of the complex, its adsorption on inorganic surfaces, and the mechanism of the polymerization induced by the supported catalyst are summarized. Much emphasis is placed on application of this technology to the realization of encapsulated filler and pigment and of coatings with improved adherence and solvent resistance. In the field of composite materials, it is demonstrated from several examples that the encapsulation of the filler can be a way to block chemical interactions between filler and matrix, to promote filler dispersion, and to improve mechanical properties.
Analysis of molecular orientation and internal stresses in extruded plastic sheets
Authors: Chan T. W. D. , Lee L. J. 
Published: December 2004

AbstractThe development of molecular orientation and internal stresses in extruded sheet made of polypropylene was analyzed, and their correlations to operating conditions such as draw ratio, cooling rate, die temperature, melt temperature, and die gap opening were studied. Measurements of attenuated‐total‐reflectance infrared dichroic ratio for the surface molecular orientation, birefringence for the orientation stress distribution in the thickness direction, and free shrinkage ratio for the overall frozen‐in stresses were carried out to determine the amount of orientation stresses in the extruded samples. As expected, the overall orientation stress depends strongly on draw ratio, while higher melt temperature reduces the overall orientation. It was found that faster cooling rates and lower die temperatures cause surface orientation stresses to increase as the core orientation stresses remain almost unchanged.
Use of the frequency dependence of the impedance to monitor viscosity during cure
Authors: Kranbuehl D. , Delos S. , Hoff M. , Haverty P. , Freeman W. , Hoffman R. , Godfrey J. 
Published: December 2004

AbstractThe ability to conveniently and continuously measure the processing properties of polymer resins is important both to the resin supplier and to the fabricator. Frequency dependent electromagnetic sensors (FDEMS) provide an in‐situ technique for continuous measurement of the resin's rheological changes both in a laboratory press and in manufacturing tools in an autoclave. In this paper the frequency dependence of ϵ*(w) is used to quantitatively monitor the viscosity for a tetraglycidyl 4,4′‐diaminodiphenyl methane (TGDDM) amine epoxy, to quantitatively monitor the viscosity during processing In a styrene‐polyester resin, and to monitor the cure process in an autoclave during cure of a high temperature polyimide‐graphite prepreg. In addition, the technique is used to measure the viscosity at various ply positions in a thick TGDDM graphite epoxy laminate during processing in an autoclave.
Isothermal and temperature programmed kinetic studies of thermosets
Authors: González‐Romero V. M. , Casillas N. 
Published: December 2004

AbstractDifferential Scanning Calorimetry (DSC) is a popular method for the characterization of the cure kinetics of thermosetting materials. The experiments may be carried out under isothermal or temperature program modes. Several authors have pointed out the fact that the kinetic rate expressions for non‐isothermal experiments must be different from the isothermal ones; however, this fact has been neglected in practice. In this work, we present a kinetic characterization of a thermosetting system using a phenomenological model for the reaction rate expression and DSC data from isothermal and non‐isothermal experiments. In general, thermosetting materials exhibit the vitrification phenomenon which stops the reaction before complete conversion is achieved. Vitrification is taken into account in both Isothermal and temperature programmed experiments.
Evaluation of dielectric cure models for an epoxy‐amine resin system
Authors: Lane John W. , Khattak Rangin K. , Dusi Mark R. 
Published: December 2004

AbstractThe parallel‐plate test fixture on a Rheometrics viscometer was electrically isolated so that the rheological and dielectric properties of a thermoset polymer system could be simultaneously measured. This enabled the relationship between the dielectric properties and the rheological properties to be directly examined. A close relationship was established between the dielectric properties (dipole relaxation time and specific conductivity) and the pre‐gelation bulk viscosity. This relationship suggested that models similar in form to those used to describe the change in viscosity might be used to describe the changing dielectric properties. The limitations and advantages of two such models, which attempt to describe the time‐temperature behavior of the dielectric properties, were then tested for use with a typical aerospace epoxy resin system.
Curing of polyimides
Authors: Feger Claudius 
Published: December 2004

AbstractThe imidization of films of the polyamic acid obtained from reaction of pyromellitic dianhydride (PMDA) with oxydianiline (ODA) was studied by dynamic mechanical thermal analysis (with the Polymer Labs DMTA), Two process regions are observed. The first process is characterized by decomplexation of the NMP/polyamic acid complex, plasticization, and imidization. The heating rate determines the character of the first process. At high temperatures (above 300°C) the second process becomes apparent. It is connected to the increase in chain mobility at these temperatures which allow molecular packing processes (densification, ordering) to occur. The ordering leads to an increase of the storage modulus. The particular transition temperature increases with annealing time.
Reducing residual stresses in molded parts
Authors: Liou Ming J. , Suh Nam P. 
Published: December 2004

AbstractMeans of reducing the flow‐induced residual stresses in injection molded parts through optimization of the thermal history of the process are presented. An approach through the use of a passive insulation layer with low thermal inertia on the cavity surface was investigated. The passive insulation layer prevents the polymer melt from freezing during mold filling and allows the flow‐induced stresses to relax after the filling. The criteria for the optimal thermal properties and the required thickness of the layer are presented. A numerical simulation model of non‐isothermal filling and cooling of viscoelastic materials was also used to understand the molding process and to evaluate this approach. This model predicts the stress development and relaxation in the molding cycle. Both simulation and experimental results show that the final stresses in the molded parts can be reduced significantly with the use of an insulation layer. This technique can also be applied to other molding or forming processes in order to decouple the material flow and cooling process for minimum residual stresses in the molded parts.
Flow of a temperature dependent power‐law model fluid between parallel plates: An approximation for flow in a screw extruder
Authors: Lindt J. Thomas 
Published: December 2004

AbstractThis paper formulates concisely the problem of fully developed flow of a temperature dependent power‐law fluid between parallel plates. An exact solution, in the absence of pressure gradients, is developed. The method has been validated by a comparison with an independent numerical solution. This work is applicable to melt transport in shallow partly filled screw channels, drag flow regimes in the metering zone of a screw extruder and, generally, to flows in hydrodynamically thin layers associated with negligible pressure gradients. A numerical example is included dealing with the extrusion of polypropylene. A general discussion is given concerning the utility of the new theory. Effects of pressure gradients are included in the discussion.
Impact fracture energy of mineral‐filled polypropylene
Authors: Chen Le‐Shang , Mai Yiu‐Wing , Cotterell Brian 
Published: December 2004

AbstractThe impact fracture energy (Gc) for a polypropylene homopolymer and a copolymer with and without calcium carbonate fillers was measured over a range of temperatures between −40°C and 40°C using fracture mechanics principles. The fillers studied were Omyacarb (∼2.7 μm) and Winnofil (∼75 nm) and 10% by weight was added to the matrix material. These fillers did not have any appreciable effect on Gc of the copolymer‐based composites. However, the Omyacarb fillers improved Gc of the homopolymer at low temperatures (⩽20°C) due to enhanced microplastic flow as observed on the fracture surfaces. The fillers increased the stiffness of both the homopolymer and copolymer. It would appear that up to 10% of cheap calcium carbonate fillers could be added to the more expensive polypropylene to reduce the production cost without any significant loss of impact fracture energy.
Characterization of liquid crystalline polyester polycarbonate blends
Authors: Malik Tariq M. , Carreau Pierre J. , Chapleau Nathalie 
Published: December 2004

AbstractMechanical and rheological properties of blends of a thermotropic liquid crystalline polyester with a polycarbonate have been investigated. The blends are fibrillar in character and exhibit great hardness and toughness due to high degree of molecular orientation which develops during the melt blending and processing steps. Increases of the Young modulus by 100 percent are observed for blends containing only 10 percent of liquid crystalline polymer, LCP. Time‐dependent behavior of the blends was investigated by performing solid state relaxation measurements and the relaxation modulus was also found to increase by the addition of LCP. The effect is relatively small in the glassy zone of viscoelastic response, but increases through the transition and viscous flow regions. The melt viscosity of the polycarbonate is slightly shear thinning whereas that of the unblended LCP increases rapidly with decreasing shear rate at low shear rate. This suggests the presence of yield stresses as confirmed by measurements on the Rheometics RSR in the stress sweep mode. The melt viscosity of the blends was found to be similar to that of the unblended polycarbonate, but more shear‐thinning and less viscous. Preliminary results of scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) are also presented.
Novel positive deep UV resist for KrF excimer laser lithography
Authors: Endo Masayuki , Tani Yoshiyuki , Sasago Masaru , Ogawa Kazufumi , Nomura Noboru 
Published: December 2004

AbstractA novel positive deep UV resist for KrF excimer laser lithography has been developed. The resist is composed of 1,7‐bis(4‐chlorosulfonyl phenyl)‐4‐diazo‐3,5‐heptanedione as the alkaline dissolution inhibitor and an alkali‐soluble sytrene polymer as the main‐polymer. 1,7‐bis(4‐chlorosulfonyl phenyl)‐4‐diazo‐3,5‐heptanedione has great capability of alkaline dissolution inhibition. High thermal stability and excellent photobleachability at 248 nm of the compound are also characterized. The alkali‐soluble styrene polymer has a high transmittance of 70% in 1.0 μm thickness at 248 nm. The novel positive resist had an excellent property for dissolution kinetics and photobleaching. We achieved high aspect ratio half‐micron pattern fabrication in 1.0 μm thickness using the new resist.