bluuebunny/crossref_metadata_2025_split huggingface dataset:
Non‐newtonian rheological behavior of semi‐dilute ultra‐high molecular weight polyethylene solution in gel‐spinning process. 1: Concentration effect on the fundamental rheological properties
Authors: Ohta Yasuo , Murase Hiroki , Sugiyama Hiroshige , Yasuda Hiroshi 
Published: April 2004

AbstractThe rheological properties of a semi‐dilute ultra‐high molecular weight polyethylene (UHMw‐PE)/paraffin wax solution were investigated by mainly focusing on the influence of its concentration on the shear flow viscosity. It was found that the UHMw‐PE solution exhibits a shear‐thinning behavior at a very wide shear rate range from 10−4 to higher than 103 sec−1. Furthermore, this typical non‐Newtonian behavior was more obvious with a concentration increase. From the concentration dependence of the zero‐shear creep compliance or other rheological factor, it was found that the extremely large Me value of the system gives rise to various kinds of non‐Newtonian behaviors, especially those highly elastic in nature. Finally, the origin of the abnormal stress fluctuation during the steady shear measurement was found to be related to the shear‐induced structural development of the solution.
Laser‐induced plasma spectroscopy for plastic identification
Authors: Anzano J. M. , Gornushkin I. B. , Smith B. W. , Winefordner J. D. 
Published: April 2004

AbstractThe goal of this work was instant identification of post‐consumer plastics by laser induced plasma spectrometry (LIPS). LIP spectra from plastics in a 200–800 nm spectral window were compared with reference spectral libraries stored in a computer. The libraries consisted of representative spectra from different groups of recycled plastic samples. The plasma emission spectra of polyethylene terephthalate (PET), high density polyethylene (HDPE), polyvinyl chloride (PVC), low density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS) were studied. Simple statistical correlation methods including linear and rank correlations were used. The probabilities of correct identification ranged from 0.8 to 1 with values close to unity for most of the polymers studied.
Isotactic polypropylene solidification under pressure and high cooling rates. A master curve approach
Authors: La Carrubba V. , Brucato V. , Piccarolo S. 
Published: April 2004

AbstractSolidification in industrial processes very often involves flow fields, high thermal gradients and high pressures: the development of a model able to describe the polymer behavior becomes complex. Recently a new equipment has been developed and improved to study the crystallization of polymers when quenched under pressure. An experimental apparatus based on a modified, special injection moulding machine has been employed. Polymer samples can be cooled at a known cooling rate up to 100°C/s and under a constant pressure up to 40 MPa. Density, Micro Hardness (MH), Wide angle X‐ray diffraction (WAXD), and annealing measurements were then used to characterize the obtained sample morphology. Results on one iPP sample display a lower density and a lower density dependence on cooling rate for increasing pressure. Micro hardness confirms the same trend. A deconvolution technique of WAXD patterns is used to evaluate the final phase content of samples and to assess a crystallization kinetics behavior. A master curve approach to explain iPP behavior under pressure and high cooling rates was successfully applied on density results. On the basis of this simple model it is possible to predict the final polymer density by superposition of the effect of cooling rate and the effect of pressure in a wide range of experimental conditions.
Micro‐mechanical deformation mechanisms in the fracture of hybrid‐particulate composites based on glass beads, rubber and epoxies
Authors: Lee Jonghwi , Yee Albert F. 
Published: April 2004

AbstractTwo tougheners, glass beads and carboxyl terminated butadiene acrylonitrile copolymer (CTBN), are used to toughen and stiffen an epoxy thermoset. Rubber‐encapsulated glass beads are used and the hybrid particulate composites containing them are compared with those containing non‐encapsulated glass beads. Within a certain range of composition, the rubber encapsulation is found to change the interactions between glass beads and CTBN particles, resulting in an increase in fracture toughness. The toughening effect is explained by the fact that the cavities of CTBN particles are larger in encapsulation systems than in non‐encapsulation systems. As more CTBN particles are incorporated into glass bead filled epoxies, the cavitation/shear yielding mechanism of CTBN particles replaces the micro‐shear banding mechanism of glass beads as the major micro‐mechanical deformation. Rubber encapsulation seems to enable this transition of major micro‐mechanical deformation to occur at a lower volume fraction of CTBN.
Numerical analysis of a reactive extrusion process. Part I: Kinetics study on grafting of vinylsilane to polyethylene
Authors: Fukuoka Takamasa 
Published: April 2004

AbstractFor controlling a reactive extrusion process in the subsequent study. the model equations of reaction kinetics and shear viscosity were studied. We focused on a free radical reaction between the molten polyethylene and vinylsilane. The kinetics model was expressed as a reaction rate equation with an apparent rate constant. The shear dependent of reacted polyethylene was formulated by employing the modified Cross model proposed in our early study. In addition, the average molecular weight was considered to correlate the shear viscosity with the reaction kinetics, leading to a series of rheo‐kinetics formulas. The experiments were carried out in a specific batch mixer suitably designed for sampling in arbitrary periods. Their reaction conversions, molecular weight distributions, and shear viscosity were measured, respectively, with an induced coupled plasma (ICP) emission spectrochemical analyzer, a high temperature gel permeation chromatography (GPC), and a capillary rheometer. Determining the parameters in each model, a simulator is set to investigate an engineering extrusion process.
Numerical analysis of a reactive extrusion process. Part II: Simulations and verifications for the twin screw extrusion
Authors: Fukuoka Takamasa 
Published: April 2004

AbstractA newly designed extruder reactor for grafting vinyl monomers onto polyolefins was studied experimentally and theoretically. The process was made up of a self‐wiping co‐rotating twin screw extruder with a separated reaction zone and two vent zones. The reactive extrusion was performed using a linear low density polyethylene, vinyltrimethoxysilane and di‐t‐butylperoxide under different operation conditions. For the purpose of process analysis, we built a computer simulation based on the reaction kinetics and rheological models studied in the preceding paper. The flow field in the extruder was calculated by the flow analysis network (FAN) method with non‐isothermal non‐Newtonian flow conditions. The iterative procedure was organized to predict local pressure, filling factor, cumulative residence time and temperature along the extruder. Furthermore, we succeeded in representing the profiles of reaction conversion and shear viscosity. Calculated results showed good agreements with the experimental data.
Preparation and characterization of plasma‐polymerized benzonitrile films with ultrafast optical kerr effect
Authors: Zhao Xiongyan , Hu Xiao , He Yuankang , Chen Huiying 
Published: April 2004

AbstractPlasma‐polymerized benzonitrile (PPBN) thin films were successfully prepared by radio frequency glow discharge techniques. The results of Fourier transform infrared (FTIR), UV‐Visible absorption spectra, X‐ray photoelectron spectroscopy (XPS) and on‐line MS revealed that extensive conjugation has been formed in the PPBN thin films and the polymerization of benzonitrile took place mainly through the opening of carbon‐nitrogen triple bonds. The morphology characterized by field emission microscopy (FEM) indicated that the fine, homogenous and brown transparent films could be obtained at comparatively low discharge power. Furthermore, the subpicosecond time‐resolved optical Kerr effect (OKE) was used to measure the third‐order optical nonlinearity. For the first time, an ultrafast response and nonresonant optical Kerr effect of PPBN films was observed.
Cure and reaction kinetics of an anhydride‐cured epoxy resin catalyzed by N‐benzylpyrazinium salts using near‐infrared spectroscopy
Authors: Park Soo‐Jin , Kwak Gun‐Ho , Sumita Masao , Lee Jae‐Rock 
Published: April 2004

AbstractThe cure behavior and the reaction kinetics of an anhydride‐cured epoxy resin catalyzed by cationic thermal latent initiator, N‐benzylpyrazinium salts, have been investigated by a near‐infrared (NIR) spectroscopy. The spectral changes are interpreted in terms of the mechanism of cure. NIR absorption bands are due to protons connected to carbon, nitrogen, and oxygen. In this work, the homogeneous model system involves a simple addition reaction mechanism leading to an exothermic reaction between epoxide and anhydride activated groups. A comprehensive account of the origin, location, and shifts during reaction of all major NIR absorption peaks in the spectral range from 4000 to 7100 cm−1 is provided. The extent of reaction is calculated from NIR absorption band at 4530 cm−1, which depends on epoxide concentration. The utility of NIR spectroscopy to study the kinetics of epoxy cure reaction has been established. Consequently, absorbencies in the NIR spectra suitable for quantitative studies of epoxy resin reaction kinetics have been identified.
A hybrid 3D/2D finite element technique for polymer processing operations
Authors: Yu Yun‐Wey , Liu Ta‐Jo , Hsu Chaug‐Liang , Yang Yeon‐Sheug 
Published: April 2004

AbstractA hybrid 3D/2D finite element method is proposed to simulate polymeric fluid motions for various polymer processing operations that may involve complex flow geometries. The flow regime is divided into 2D and 3D regions, and the fluid flow is assumed to follow the Hele Shaw model in the 2D region. Mathematically the 2D and the 3D regions are linked by the conservation of mass and the continuation of pressure variations. Two example calculations have been used to illustrate the accuracy and efficiency of the new numerical technique, and it was found that a substantial amount of computing time can be saved to obtain numerical solutions that are as accurate as the complete 3D calculations.
Some thermodynamic and kinetic properties of the system PETG‐CO2, and morphological characteristics of the CO2‐blown PETG foams
Authors: Paul Handa Y. , Wong Betty , Zhang Zhiyi , Kumar Vipin , Eddy Sharon , Khemani Kishan 
Published: April 2004

AbstractThe solubility of CO2 in PETG, a glycol‐modified PET, was measured at different temperatures and over a broad pressure range, and diffusion coefficients were derived at the corresponding conditions. The solubility of CO2 is quits high. For example, almost 15 wt% CO2 can be dissolved in PETG at 35°C and 6.0 MPa. Consequently, CO2 is good blowing agent for PETG. Cellular foams in the density range of about 0.04 to 1.2 g/cm3 and diameters in the range of about 10 to 150 µm were produced. The foam density and the cell size were found to depend on the foaming temperature and time, with larger cells obtained at higher temperatures or when the sample was foamed for a longer time. The foam density decreased with an increase in the foaming temperature to about 90°C, beyond which the density tended to increase slightly due to the cell collapse or coalescence. The density reduction also depended on the pressure at which the polymer was saturated with CO2; the higher the saturating pressure at a given temperature, the greater the density reduction.
Study of “gas fingering” behavior in gas‐assisted injection molding
Authors: Lu X. , Chiang H. H. , Fong L. , Zhao J. , Chen Shia Chung S. 
Published: April 2004

AbstractA common problem encountered in gas‐assisted injection molding (GAIM) is “gas fingering,” i.e., gas bubbles penetrating outside designed gas channels and forming finger‐shaped branches. Severe gas fingering can result in significant reductions in part stiffness. In this paper, nondestructive techniques have been used to quantitatively characterize gas bubble geometry in specially designed GAIM parts. Based on the quantitative measurements, the most crucial process parameters to control gas fingering have been identified through factorial design experiments. More detailed process studies reveal that there is an intrinsic relationship between gas fingering and cross‐sectional gas bubble shape. By examining the effects of gas channel design and material type on the gas bubble shape, some useful gas channel design guidelines have been obtained.
Enhancement of fiber structure formation of a liquid crystalline copolyester via ultra‐high speed bicomponent spinning with poly(ethylene terephthalate)
Authors: Radhakrishnan J. , Ito H. , Kikutani T. , Okui N. 
Published: April 2004

AbstractA thermotropic liquid crystalline copolyester, poly(hydroxybenzoic acid‐co‐ethylene terephthalate) (LCP), and poly(ethylene terephthalate) (PET) were coextruded using two different extrusion systems to form sheath‐core type biocomponent fibers. The bicomponent fibers could be spun up to a take‐up velocity of 8 Km/min. The structural characterization of the individual components in the as‐spun fibers showed that the orientation development in the PET component was significantly suppressed compared with the corresponding single component fibers. A significant increase in the tensile modulus of the LCP core component, which was estimated by the simple rule of mixtures, was observed above a take‐up velocity of 4 km/min. The increase in tensile modulus was attributed to the increase in the overall orientation of the LCP core resulting from the combination of the high levels of stress generated during spinning at very high speeds and the altered thermal and stress generated during spinning at very high speeds and the altered thermal and stress histories provided by the bicomponent spinning process. On‐line study of the thinning behavior of single component and bicomponent spinning was carried out in order to gain an understanding of the spinline dynamics, which improved the processability and structure development of LCP.
Synthesis of protective coatings on steel by surface spontaneous polymerization. 3: Process development and coating property studies
Authors: Zhang Xu , Bell James P. 
Published: April 2004

AbstractWe have previously reported a new method for applying protective coatings on metal surfaces, the Surface Spontaneous Polymerization Process (1). In this process, polymerization occurs spontaneously on the substrate upon immersion into a monomer solution, forming a layer of uniform coating in‐situ. No initiator is added. In this paper, studies on the development of the process and coating properties are reported. A monomer reaction system containing phenylmaleimide/styrene/bismaleimide/2‐(methacryloyoxy)ethyl acetoacetate has been developed to afford protective coatings on steel. The coatings obtained from this system have good thermal, dielectric, and adhesion properties. Corrosion resistance of 4CPMI coatings, as measured by the ASTM B‐117 salt spray test, is excellent after 700 hours of salt spray. The effects of several process variables on the polymer molecular weight were also studied, including monomer concentration, solution temperature, solution pH, and monomer feed composition. Solution stability studies indicate that polymerization occurs only on the surface and does not propagate into the solution.
Numerical simulation of three‐dimensional viscoelastic flow within dies
Authors: Kihara S. , Gouda T. , Matsunaga K. , Funatsu K. 
Published: April 2004

AbstractIn recent years, the development of CAE (Computer Aided Engineering) in polymer processing has been remarkable, and it is expected to be more realistic in viscoelastic numerical simulation, particularly in three‐dimensional complex geometry. Because of the problems of computational memory capacity, CPU time, and the numerical convergence of viscoelastic flow simulation, three‐dimensional viscoelastic simulation applicable to industrial flow behaviors has not yet been attempted. In this paper, we developed the numerical simulation of three‐dimensional viscoelastic flow within dies using a decoupled method, streamwise integration, and penalty function methods to decrease memory, and the TME (“Transformation of Equation of Motion to the Elliptic Equation,” S. Tanoue, T. Kajiwara, and K. Funatsu, The Eleventh Annual Meeting, the Polymer Processing Society Seoul, Korea, Extended Abstracts p.439) method, which raises the stability of convergence. We confirmed the reliability of this simulation technique to compare simulation results with experimental data of the stress field at a downstream wall shear rate of 5.41s−1 within a 60° angle tapered contraction die. We compared the predictions of a viscoelastic model (Phan‐Thien and Tanner model) with a pure viscosity model (Carreau model) at a downstream wall shear rate of 120s−1 and discovered a remarkable effect of viscoelasticity in the shear stress and first normal stress difference in particular in the tapered region.
Formation of integral skin polyurethane foams
Authors: Gupta V. K. , Khakhar D. V. 
Published: April 2004

AbstractPolyurethane integral skin foams comprise a low density foamed core surrounded by a high density skin of the same material, and are made in a single molding operation. Polyurethane integral skin foams find wide application as structural materials, and the mechanical properties of such foams are significantly affected by the foam structure, which in turn is determined by the foaming process. An experimental and theoretical study of the foam formation process is presented. Experimental results show that increase in the mold wall temperature results in an increase in the upper skin thickness, a decrease in the lower skin thickness, and a decrease in the density of both skins. The core density increases with increasing wall temperature. Increase in the blowing agent concentration produces a small increase in the skin thickness. Computations based on the model of Marciano et al. [Polym. Eng. Sci., 26, 717 (1986)] are presented using an efficient numerical technique. Predictions of the model for the skin thickness, core density and pressure and temperature variation with time are in reasonable agreement with experimental data. The model, however, predicts higher skin densities than the experimental measurements. A modification of the initial condition of the model to account for the air bubbles dispersed during mixing gives better agreement between theory and experiment.
Controlled orientation of reflective pigment and optical property characterization of injection‐molded polypropylene
Authors: Rawson Keith W. , Allan Peter S. , Bevis Michael J. 
Published: April 2004

AbstractThe aims of the research reported were to explore the possibility of removing surface weld lines from highly reflective aluminum pigmented polypropylene injection moldings. Moldings were optically characterized and their characteristics attributed to pigment orientation present in the samples. Conventional injection molding and two novel molding techniques were employed for this investigation, Shear Controlled Orientation Injection Molding (SCORIM) and Bright Surface Molding (BSM). Further, the two techniques, SCORIM and BSM, were used in series and termed SBM to remove surface weld lines. The use of SBM enabled the re‐orientation of the pigment in order to induce a uniform direction for the “flip‐flop” effect where flow fronts have impinged from different directions. These moldings were then quantitatively characterized using a gonio‐spectrophotometer. Their different reflective surface characters were then related to the angle of orientation induced by the respective processing technologies used.
Shear yield behavior of calcium carbonate–filled polypropylene
Authors: Wang Yeh , Wang Jyun‐Jye 
Published: April 2004

AbstractThe rheological properties of calcium carbonate‐filled polypropylene has been examined using a Rheometrics dynamic analyzer RDAII. The study included a steady shear test, a transient stress growth test, and a dynamic oscillatory shear flow. Yield behavior was observed in all kinds of rheological tests for highly filled compounds when the volume loading exceeded a critical value at about 20%. The empirical Cox‐Merz rule, which is usually applicable to an unfilled polymer, was found to be invalid for highly filled compounds. The modified Cox‐Merz rule, in which the apparent viscosity versus the shear rate is equal to the complex viscosity versus the frequency‐amplitude in the nonlinear region, was found to be valid only for highly filled compounds. The viscosity and the apparent yield values appear to increase with increasing volume loading of filler particles. The surface treatment of fillers, which presumably reduces the interaction between filler particles and the extent of agglomeration, results in major viscosity reductions and decreases in apparent yield values. The yield values determined from various tests are not the same. The results are interpreted in terms of a system forming a filler network due to weak inter‐particle forces. The yield stress resulting from the breakdown and recovery of the network is thus dependent on the characteristic time of the individual test.
A continuous test data method to determine a reference curve and shift rate for isothermal physical aging
Authors: Bradshaw R. D. , Brinson L. C. 
Published: April 2004

AbstractThe mechanical response of a material undergoing isothermal physical aging is governed by a reference curve (typically time‐dependent modulus or compliance) and a shift rate (which describes the rate of aging). In the standard analysis approach, these parameters are determined from a series of load/unload creep or relaxation tests, in which only the load portion data is used for property evaluation. In this paper, a new continuous test data (CTD) method is presented to determine these parameters using both the load and unload data from such a test series. This is accomplished by employing effective time theory to predict the full load/unload data set, with the reference curve and shift rate obtained as those which best fit the experimental data. It is demonstrated that the references curve obtained via the standard approach is not capable of predicting the full load/unload data set, while the CTD method using a Prony series fits this same data very well. Several concerns regarding the CTD method are addressed, including the differences in the CTD and standard method shift rate, the effect of vertical shifting or material nonlinearity on the results, and application of the method to other loading scenarios. Results are presented for long‐term and variable stress tests. The data used in the study was obtained from polyimide resin and polyimide/carbon fiber composite specimens at several temperatures below Tg.
Relationship between surface potential and second harmonic generation in chromophore‐doped poly(ethylene oxide)/atactic‐poly(methyl methacrylate) blends
Authors: Vannikov A. V. , Vernel J. , Mal'Tsev E. I. , Savel'Ev V. V. , Rychwalski R. W. 
Published: April 2004

AbstractThe intensity of second harmonic (SH) light, generated by passing a laser beam through corona poled films of poly(ethylene oxide)/atactic‐poly(methyl methacrylate), PEO/a‐PMMA blends molecularly doped by 4‐anilino‐4'‐nitroazobenzene (DO3), is studied as a function of time, temperature, and composition. SH intensity decay kinetics at room temperature is entirely controlled by the time‐dependent surface potential decrease (SPD). In turn, the SPD is determined by the conductivity of polymeric films and the free volume. The latter is a function of temperature history and blend composition.