bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow patterns in calcium carbonate and titanium dioxide filled polyethylene in the entrance region of a capillary die
Authors: Ma Chin‐Yuan , White James L. , Weissert Frederick C. , Min Kyonsuku 
Published: May 2005

AbstractExperiments to determine the influence of calcium carbonate and titanium dioxide on flow patterns in die entrance regions are reported. The addition of loadings of calcium carbonate and tatanium dioxide of 5 volume percent and more is found to suppress the development of vortices in low density polyethylene at the entrance of a 180° entrance angle die. Vortex suppression was found in more complex entrance regions as well. Similar behavior has been found for carbon black compounds.
Some properties of polypropylene filled with metal fibers
Authors: Katsura T. , Kamal M. R. , Utracki L. A. 
Published: May 2005

AbstractPolypropylene/steel fiber composites were prepared and tested for mechanical, electrical, and permeability performance. To enhance adhesion of polypropylene to steel fibers, two kinds of coupling agents, maleated polypropylene wax and maleated polypropylene, were used. It was found that maleated polypropylene wax was more effective. However, as indicated by permeability measurements and scanning electron microscopy (SEM), adhesion was rather poor. Oxygen and water vapor permeabilities of the polypropylene/steel fiber composites increased with the steel fiber concentration. The lack of adhesion at the fiber‐polymer interface created diffusive paths for the gas to penetrate the composite. Addition of polyamide to polypropylene caused a decrease in the permeability of the system, due to a reduction of the permeability of the matrix. The polypropylene/steel fiber composites become conductive at a volume loading of about 10 percent. At this concentration the volume resistivity of the composite is 10.8 ohm cm.
Electromagnetic interference shielding with nickel‐coated mica composites
Authors: Kortschot M. T. , Woodhams R. T. 
Published: May 2005

AbstractThe topic of electromagnetic interference (EMI) has been reviewed briefly to outline the need for conductive composite materials. The characteristics of a conductive filler which lead to high efficiency at small filler concentrations were examined qualitatively. One of these characteristics, aspect ratio, was examined in detail by using nickel‐coated micas as a means of molding composites containing ultra‐thin layers of nickel. Using this technique, as little as 1.5 volume percent nickel can provide adequate shielding for 90 percent of current commercial applications.
Tetraglycidyl epoxy resins and graphite fiber composites cured with flexibilized aromatic diamines
Authors: Delvigs Peter 
Published: May 2005

AbstractStudies were performed to synthesize new ether modified, flexibilized aromatic diamine hardeners for curing epoxy resins. The effect of moisture absorption on the glass transition temperatures of a tetraglycidyl epoxy, MY 720, cured with flexibilized hardeners and a conventional aromatic diamine was studied. Unidirectional composites, using epoxy‐sized Celion 6000 graphite fiber as the reinforcement, were fabricated. The room temperature and 300°F mechanical properties of the composites, before and after moisture exposure, were determined. The Mode I interlaminar fracture toughness of the composites was characterized, using a double cantilever beam technique to calculate the critical strain energy release rate,GIC.
Evaluation of fiber‐matrix interphasial toughness in unidirectional composites
Authors: Newaz Golam M. 
Published: May 2005

AbstractInterphasial toughness was evaluated for polyester and epoxy unidirectional glass fiber reinforced composites using single edge‐notched specimens. This was accomplished via a calculation of an energy term based onJ‐integral which accounted for the energy required to form a longitudinal split crack ahead of the original notch. It was found that the fiber‐matrix interphasial fracture resistance of the epoxy composite is substantially greater than that of the polyester composite. This technique may be an excellent way of evaluating the interphasial quality in unidirectional composite laminates.
Effect of the filler/polymer interface on the mechanical and morphological properties of a composite based on polyethylene blend matrices
Authors: Arroyo M. , Perez F. , Vigo J. P. 
Published: May 2005

AbstractA series of composites based on low and high density polyethylene blend matrices with unmodified and previously organophylized sepiolite as filler have been prepared. In the latter case, isopropyl‐methacryl‐diisostearoyl titanate (KR‐6) was used as coupling agent. The Box‐Hunter Statistical Method was used to obtain the maximum information through a wide matrix composition and filler content range from a small number of experiments. The organophylization of the filler has hardly shown any improvement on the tensile, flexural, and impact properties of the composite. A morphological study carried out by means of scanning electron microscopy has shown that the organophylization tends to modify the surface textural characteristics of the sepiolite, compensating the effect of the coupling agent on the properties.
Dynamic mechanical behavior of binary blends polyethylene/EPDM rubber and polypropylene/EPDM rubber
Authors: Kolařík J. , Agrawal G. L. , Kruliš Z. , Kovář J. 
Published: May 2005

AbstractThe dynamic mechanical behavior of the binary blends high‐density polyethylene/EPDM rubber (ethylene‐propylene‐diene terpolymer) and isotactic polypropylene/EPDM rubber was investigated by means of a free‐oscillating torsional pendulum. Comparison of the moduli of the systems studied and predictions drawn from several models show that phase inversion in the polyethylene/EPDM blends takes place at the volume fraction vPE = 0.5, while polypropylene preserves a certain phase continuity also as the minor component (0.5 > vPP > 0.2) in blends with EPDM. Because of faster shrinkage in the course of cooling, inclusions are exposed to negative hydrostatic pressure, which accounts for a drop in the glass‐transition temperature of the rubber. The strength of the relaxation associated with the glass transition of inclusions and tensile impact strength increase proportionately to the rubber content in polypropylene (0 < vEPDM < 0.4). Dynamic mechanical response spectra of commercial EPDM/polyethylene impact modifiers are compared with the results for model systems.
Application of ductile polymeric coatings onto graphite fibers
Authors: Bell J. P. , Chang J. , Rhee H. W. , Joseph R. 
Published: May 2005

AbstractThin, high molecular weight copolymers have been applied to the surfaces of commercial, 8 micron diameter, graphite fibers by electropolymerization. Random copolymers were obtained, and the process appears to be consistent with the rules of standard free radical copolymerization. Coating thickness, Tg, and modulus can be systematically controlled. Very preliminary mechanical property measurements indicate a substantially improved impact strength and reduction in the interlaminar shear strength. These effects may be related to poor adhesion between the interlayer and the epoxy resin, however, which may be corrected by use of a “top layer” of appropriate composition.
Poly(aryl‐ether‐ether‐ketone) and its advanced composites: A review
Authors: Nguyen Huy X. , Ishida Hatsuo 
Published: May 2005

AbstractPoly(aryl‐ether‐ether‐ketone) or PEEK is a highly aromatic semi‐crystalline thermoplastic. Its good mechanical properties and solvent resistances rank it as one of the most promising matrix polymers for high performance composites. This article attempts to provide an in‐depth review of work on PEEK and fiber‐reinforced PEEK composites. Discussions on various areas including synthesis, molecular weight determination, solution properties, structural hierarchy, morphology and mechanical properties of both neat polymer and composites, will be provided. In addition, environmental effects such as physical aging, thermal aging, moisture, solvents, and radiation will be summarized.
A nondestructive method to determine material properties in orthotropic plates
Authors: Fällström K‐e , Molin N‐e 
Published: May 2005

AbstractAn electronic speckle pattern interferometer (ESPI) is used to determine modes of vibration in rectangular, orthotropic, free‐free plates; that is using a noncontact, nondestructive, optical method. It is shown, using the finite element method (FEM), that each of the first three modes of vibration in rectangular orthotropic plates has a strong dependence upon only one of the main material parameters, namely the in‐plane shear modulus and the two Young's moduli, respectively. With this one‐variable dependence it is a simple task to determine the effective material parameters. This method has several obvious advantages compared to the use of test bars and it can be extended to give a measure of the damping parameters and probably also be used for production control. Preliminary results are presented and discussed.
Mechanical properties of particulate filled polymers
Authors: Bigg D. M. 
Published: May 2005

AbstractThe mechanical properties of several types of inorganic fillers were investigated in a number of different thermoplastic polymers. The fillers included minerals, such as talc and silicon carbide, and metals, such as aluminum flake and stainless steel fibers. The polymers included General Electric's Noryl, acrylonitrile‐butadiene‐styrene terpolymer, polypropylene, and modified polypropylene. The talc and some of the aluminum flake were treated with coupling agents to improve interfacial adhesion to the polymers. The results showed that the modulus of the filled polymers was a function only of the concentration of filler used up to 40 volume percent filler. The tensile strength of the filled compositions depended very strongly on the degree of interfacial bond developed between the polymer and the filler. The interfacial bond strength depended on the effectiveness of the coupling agents and the inherent wetting ability of the polymer. Of the polymers investigated in this study, Noryl showed the greatest degree of inherent wetting to inorganic fillers. Chemical modification of polypropylene also resulted in greater adhesion to fillers. The impact strength of filled compounds had an even more complex response, because, in addition to the concentration of the filler, and strength of the polymerfiller interface, it depends on the mechanism of crack propagation.
Cellulose fiber‐polyester composites with reduced water sensitivity (1)—chemical treatment and mechanical properties
Authors: Hua Li , Zadorecki Pawel , Flodin Per 
Published: May 2005

AbstractFormaldehyde and di‐methylomelamine were used to modify the surfaces of cellulose fibers. Composites were prepared with unsaturated polyester and treated cellulose as the reinforcing material. The tensile strength and the elongation of the cellulose fibers were determined in dry and wet conditions as well as the tensile strength and the tensile modulus of the cellulose‐polyester composites. The water uptake of the composites was reduced by 46 to 52 percent. The wet strength of the composites was improved by more than 50 percent.
Micromechanisms of interlaminar fracture and fatigue
Authors: Russell Alan J. 
Published: May 2005

AbstractThe interlaminar fracture and fatigue properties of AS/3501‐;6 graphite/epoxy are discussed from a mechanistic point of view. Particular emphasis is placed on the interaction between the loading mode and the local geometry of the interlaminar zone and on how this affects the stresses close to the crack tip and the resulting failure path. Delamination growth under Mode I loading is shown to depend on the likelihood of fiber bridging occurring and on how effective these bridged fibers are at diverting strain energy away from the crack tip. The Mode II behavior is controlled by both the work required to shear the fibers from the matrix and the ease with which tensile failure of the matrix between the fibers can occur.
Controlling and monitoring interfacial reactions in composites of azidosilane modified glass filled polyethylene
Authors: Miller James D. , Ishida Hatsuo , Maurer Frans H. J. 
Published: May 2005

AbstractModel composites of spherical glass particles dispersed in a matrix of high density polyethylene were prepared with controlled variations in the interfacial structure. Dynamic‐mechanical measurements of the composites in the melt state were recorded. The physical properties are found to relate to the morphology, bonding, reactivity, and other characteristics of the interfacial region which can be controlled by the applied chemistry. The interfacial reactions can be monitored in‐sity by dynamic‐mechanical analysis and differential scanning calorimetry.
Computer simulation of the electrical conductivity of polymer composites containing metallic fillers
Authors: Kortschot M. T. , Woodhams R. T. 
Published: May 2005

AbstractIn this study, a theoretical basis for the use of conductive composites was established. A percolation simulation program was used to determine critical area fractions for dispersions of rectangles in two dimensions. Both the aspect ratio and orientations of the rectangles were varied independently, and the simulation results were used to predict the effect of these parameters on the critical concentration of conductive flakes in a filled polymer. Above a certain aspect ratio defined as the “scaling limit,” the critical area fraction for rectangles was inversely proportional to aspect ratio. The scaling limit was smallest for a set of randomly oriented rectangles, and its value became larger as greater degrees of alignment were imposed. The smallest critical area fractions belonged to high aspect ratio, randomly oriented rectangles. The predictions of percolation theory were compared with results for dispersions of nickel‐coated mica in fine glass powder and in compression molded polyethylene. The critical volume fraction of mica was inversely proportional to flake aspect ratio over the range of aspect ratios tested. Electromagnetic interference (EMI) shielding effectiveness was examined for composites containing both aligned and randomly oriented flakes. For a given filler loading, the shielding effectiveness of the aligned flake composites was substantially lower than that of the composites containing randomly oriented flakes.
Testing of new‐generation carbon fiber/toughened resin epoxy systems
Authors: Poon C. , Scott R. F. , Lee S. 
Published: May 2005

AbstractFour commercially available carbon fiber/prepreg systems were processed and subjected to NASA's proposed standard tests for toughened resins. Narmco Materials Inc. Rigidite T300/5208 was included as a baseline, while the other three systems employed Hercules' IM6 fiber in newgeneration resin systems. Descriptions of the tests, including open‐hole tension and compression, compression after impact, double cantilever beam, and edge delamination tension, as well as results are presented.
Polypropylene/low density polyethylene blend matrices and short glass fibers based composites. I. Mechanical degradation of fibers as a function of processing method
Authors: Arroyo M. , Avalos F. 
Published: May 2005

AbstractThe fiber length degradation during compounding (two‐roll milling and twin‐screw extrusion) of glass fiber and polypropylene (PP)/low density polyethylene (LDPE) blend matrices based composites was investigated. The effect of LDPE percentage and fiber content on fiber length were studied using a semiautomatic image analysis system. Two‐roll milling causes a more severe attrition of the fibers than twin‐screw extrusion. In the first case, the higher the LDPE percentage in the polymer matrix, the larger the final fiber length. Both methods lead to a broader fiber length distribution as LDPE percentage increases. The effect of fiber content is opposite to that of the LDPE percentage, but in the case of twin‐screw extrusion it is less noticeable, During the injection molding of the composites a slight decrease of the final fiber length takes place. This decrease depends on the initial fiber length, the effect being more pronounced for longer fibers.
Study of interfaces of high‐performance glass fibers and DGEBA‐based epoxy resins using single‐fiber‐composite test
Authors: Netravali A. N. , Schwartz P. , Phoenix S. L. 
Published: May 2005

AbstractThe single‐fiber‐composite (SFC) technique was used to study the interfacial behavior between two flexible blends of diglycidylether of bisphenol A (DGEBA)‐based epoxy and polyglycol epoxide and three glass fibers. Dog‐bone‐shaped SFC specimens were made and strained to obtain a distribution of fragment lengths. The fibers were tension‐tested at two different gauge lengths. The fragment length distributions, the fiber strength data, and a Monte Carlo simulation of a Poisson/Weibull model for fiber strength and flaws were used to obtain the effective interfacial shear strength values. The results show that the interface does not fail. Instead, penny‐shaped transverse cracks appear at every fiber break and grow as the specimen is strained. The interfacial shear strength values are many times higher than the yield shear strength values of bulk epoxy obtained from the tension test.
Interfacial shear strength studies using the single‐filament‐composite test. Part II: A probability model and Monte Carlo simulation
Authors: Henstenburg R. B. , Phoenix S. L. 
Published: May 2005

AbstractA Monte Carlo simulation is developed to provide a foundation for interpreting experimental data from the single‐filament‐composite test. The main focus is on developing an improved procedure for arriving at a realistic value for the shear strength of the fiber‐matrix interface, but it is also shown how the test may be used to characterize the strength distribution of fibers at a length scale much shorter than is achievable in standard tension tests. The simulation is based on the widely used Poisson/Weibull probability model for fiber failure that characterizes the strength in terms of the random flaws distributed along the fiber. The primary mechanical model for stress buildup at the fiber end is the same as that assumed by most authors and assumes a constant interfacial shear stress in this shear transfer zone reminiscent of a yielding plastic matrix. We also, however, consider a bilinear model that allows for a zone of debonding with a constant shear stress lower than in the primary “plastic” zone. Simulation results are cast in terms of nondimensional variables and tabulated to allow for wide applicability. Sample size and confidence interval issues are also discussed.
Short‐fiber‐reinforced thermoplastics. Part III: Effect of fiber length on rheological properties and fiber orientation
Authors: Vaxman A. , Narkis M. , Siegmann A. , Kenig S. 
Published: May 2005

AbstractThe effect of fiber length on fiber‐filled melt viscosity and on shear‐induced fiber breakage and orientation development in polystyrene was studied. The incorporation of fibers, increasing their length, results in an increasing viscosity over the entire shear rate range. Significant fiber length reduction was observed even at low shear rates. Determined fiber orientation distributions, as affected by shear rate and fiber length, are discussed. Orientation effects are expressed by a single orientation parameter which is used to account for the average fiber orientation contribution to the relative viscosity. Calculated orientation parameters indicate higher fiber orientation for shorter fibers. Fiber orientation in the flow direction increases with increasing shear rate and results in the expected viscosity decrease.
Prediction of internal stresses in a circular bilayered laminate glass‐resin
Authors: Aboulfaraj M. , Schirrer R. , Wippler C. 
Published: May 2005

AbstractA previous paper has shown how it is possible to determine the stress induced in a bilayered circular laminate glass‐resin under various conditions with a nondestructive method. In this paper a more precise mathematical analysis which allows prediction of the stress with time is given. In order to determine numerical values from the theoretical calculations, the relaxation function of the resin, g(t, T), and the shift factor, aT, of the time‐temperature superposition principle have to be known. The relaxation function measured with the experimental setup, under biaxial stress conditions appears to be identical with the one determined by another laboratory under uniaxial compression stress. A systematic exploration of the influence of the different parameters, g(t, T), aT and the thermal expansion coefficient, α(T), shows that the most difficult parameter to determine with sufficient precision is aT. Working under different cooling conditions the experimental results have been compared with the theoretical predictions. The agreement is generally good and even very good for the fast cooling cycle for the final stress if one takes into account the thermomechanical properties of the resin during and after its curing.
Weathering of glass‐fiber‐reinforced polystyrene and poly(ethersulfone)
Authors: Qayyum M. M. , White J. R. 
Published: May 2005

AbstractGlass‐fiber‐reinforced polystyrene (GFPS1) and polyethersulfone (GFPES) injection‐moldings containing 20 wt% glass have been weathered in Jeddah, Saudi Arabia, for up to one year. The retained strength and ductility were, generally, better than in the corresponding unreinforced polymers. The tensile strength fell to ca 73% of the initial, unexposed value, (GFPS1) and ca 77% (GFPES), whereas the extension to break values fell to ca 50% and 76%, respectively, after one year of weathering. The inclusion of carbon black in reinforced polystyrene (GFPS(B)) resulted in a barely perceptible drop in strength (to ca 98%) and a greatly improved reduction in extension to break, dropping only to ca 81% after one year. Residual stress levels were measured and were found to be insufficient to have a significant influence on fracture behavior. In GFPES they were generally less than 2MN/m2except at a location ≃0.3 mm from the surface, where compressive stresses of up to 4 MN/m2were present. No significant change in residual stress occurred with exposure in GFPES. With GFPS1 the stress levels were insignificant ( <1 MN/m2) through most of the bar both before and after exposure. With unexposed GFPS(B) the stresses were <1 MN/m2except within 0.2 mm of the surface, where they rose steeply, though probably not above 5 MN/m2. After weathering the stresses were everywhere <1 MN/m2, but the sense of the residual stresses had reversed near to the exposed surface. This is attributed to radiant heating, and is undesirable because it may lead to distortion.
Random glass mat reinforced thermoplastic composites. Part II: Analysis of model materials
Authors: Stokes Vijay K. 
Published: May 2005

AbstractThe mechanical properties of random continuous glass mat reinforced composites, as determined by standard tensile tests, are known to have a very large scatter. New test procedures have shown that the tensile modulus in these materials can vary by a factor of two over a 12.7‐mm (½‐in) distance. The elastic modulus in a 150 × 305‐mm (6 × 12‐in) plaque can vary by a factor of three. In order to understand the effects of the gauge length on the properties of such materials measured in tensile and flexural tests, a simple model, in which the tensile elastic modulus is modulated by a spacewise sinusoidal variation, has been analyzed. The effect of the functional form of the modulus variation has been assessed by analyzing a square‐wave variation.