bluuebunny/crossref_metadata_2025_split huggingface dataset:
The silane/sizing composite interphase
Authors: Al‐Moussawi Hassan , Drown Edward K. , Drzal Lawrence T. 
Published: May 2005

AbstractSilane coupling agents are but one of many ingredients in commercial sizings that are applied to glass fibers. The chemistry of a silane coupling agent alone allows it to react with both the glass fiber surface and the epoxy matrix to increase the fiber/matrix adhesion. However, the action of a commercial sizing system containing a silane coupling agent along with other components is not well understood. Research has been conducted in which the physical properties have been measured of blends of epoxy‐compatible silane/sizing made with bulk matrix at concentrations representing likely compositions found at the fiber‐matrix interphase as a result of processing and fabrication. It has been shown that the silane/sizing interaction with the epoxy matrix produces a material with vastly different properties than those of the bulk matrix. In this particular system, the model interphase has a lower Tg higher modulus, and greater tensile strength, but lower toughness. The results from the present study show that a themical interaction theory of adhesion alone is not sufficient to explain the role of silane coupling agents in glass fiber‐epoxy matrix adhesion. Consideration must be given to the interphase and its mechanical properties.
Hydrothermal effects on the physico‐chemical properties of pure and glass fiber reinforced polyester and vinylester resins
Authors: Ghorbel I. , Valentin D. 
Published: May 2005

AbstractThe effect of aging by immersion in water at 60°C on polyester and vinylester resins, unreinforced and reinforced with glass fibers, was investigated. Changes in weight, glass transition temperature, secondary relaxations, and storage modulus, as well as loss modulus were measured, and the environmental effects on these parameters were assessed. Moreover, the chemical structure changes of the materials during aging were studied by the use of IR spectra. The evolution of the physico‐chemical and the mechanical properties as a function of the aging time was established. The results indicate the importance of the matrix morphology, the structure regularity, the presence of the fibers on the water diffusion mechanisms, and the thermomechanical properties through gravimetric changes, DSC, DMA and IR experiments.
Prepreg process analysis
Authors: Ahn K. J. , Seferis J. C. 
Published: May 2005

AbstractA description of the hot‐melt prepreg process was developed by coupling resin matrix flow at the coating and impregnation zones with heat transfer considerations. Both bismaleimide (BMI) and epoxy resin systems were used as matrices. With continuous carbon fiber reinforcement. For the laboratory scale prepregger utilized in this study, the thickness of the resin film produced in a doctor blade was approximately 63% of the blade distance, showing good agreement with experimental data. In addition, the measured heat transfer coefficient between prepreg and atmosphere indicated that surface convective resistance is large compared to the internal conductive resistance and thus the chill plate in the prepregging operation plays on important role in determining prepreg quality. By formulating an analytical methodology in terms of the “Prepreg Flow Number” (PFN) that combined important operating parameter (e.g., temperature, pressure, and production rate), a temperature‐pressure‐velocity superposition was confirmed for the prepregging process. In addition, the model could easily be extended to different scales and types of prepregging processes with the aid of dimension‐less parameters that are quite descriptive of the operating conditions employed in prepreg manufacturing.
Evaluation of polybutene electrofusion joint performance
Authors: Nishimura Hiroyuki , Nakashiba Akio , Kawakami Ryuichiro , Inoue Fumio , Inoue Toshio , Oshimo Shinzaburo 
Published: May 2005

AbstractThis paper describes methods of evaluating polybutene electrofusion joints and results of mechanical strength measurements for an electrofusion joint. Suitable fusion conditions were determined qualitatively through measurement of fusion interface temperatures and observation of the fusion zone. A method of determining standard fusion conditions, based on the relation between heating time and tensile strength, is also indicated. Differences in thermal properties between polybutene and polyethylene resins are discussed. It was found that polybutene required less supplied power per unit fusion area for suitable fusion. It was also confirmed that an electrofusion joint required a cold zone.
Crystallization and chain adsorption of poly(etheretherketone) in discontinuous pitch‐derived carbon fiber composites
Authors: Jonas Alain , Legras Roger 
Published: May 2005

AbstractThe crystallization kinetics of poly(etherether ketone) (PEEK) in chopped mesophase pitch‐derived carbon fiber/PEEK composites have been studied. Various processing techniques are used in order to obtain controlled fiber length in the composites. Scanning electron microscopy performed on properly etched long fiber composite samples reveals that the nucleating sites density is low at the carbon fiber surface: transcrystalline layers are rarely observed. This is confirmed by differential scanning calorimetry. However, samples processed by mixing carbon fibers and molten polymer in a high temperature mixer have a widely different behavior: the nucleation density and the crystallization rate increase, the glass transition of these samples is displaced towards higher temperatures, and the solubility is dramatically lowered. We ascribe these phenomena to the adsorption of the polymer chains on carbon particles created by attrition during the mixting.
Numerical simulation on the permeability variations of a fiber assembly
Authors: Cai Zhong , Berdichevsky Alexander L. 
Published: May 2005

AbstractFinite element simulations on permeability variations of an aligned fiber assembly have been conducted. Two dimensional viscous flow in longitudinal and transverse directions has been studied respectively, using the steady state Navier‐Stokes equation but with small Reynolds numbers. Two groups of packing structures are investigated, both with introduced disturbances in the fiber assembly. One is the idealized packings, including hexagonal and square packings, but with selected fibers removed randomly, and with fiber center positions disturbed randomly. This gives random effect within the modeled cells, but on the macro‐scale the structure is still periodic. Numerical simulations are performed using available finite element packages. The result shows clearly that different physical mechanisms doninate the flow process in longitudinal and transverse permeabilities in the longitudinal flow case, the disturbance introduces openings within the bundle, and these openings become between fibers. Thus flow resistance increases substantially in the idealized packing cases. Numerical data are then compared with available data from other studies, particularly that from using self‐consistent methods.
Evaluation of test methods in the determination of in‐plane shear modulus of poly(phenylene sulfide) matrix composites
Authors: Shih Gary G. , Tseng Wen W. , Lou Alex Y. 
Published: May 2005

AbstractAn investigation was conducted to evaluate the validity of various test methods in the dtermination of in‐plane shear moduli of semicrystalline, poly(phenylene sulfide) (PPS) thermoplastic composites. Materials studied included composites based on an orginal, non‐optimized composite grade of PPS reinforced with carbon and glass fibers, and another based on the new improved, high‐ductility, rapid crystallizing, composite grade of PPS along with optimally sized glass fiber reinforcement. Specimens were prepared in a matched die mold, either as‐molded or annealed. It was found that shear test methods, such as ±45° in plane, Iosipescu, and 45° pff‐axis tension, are validfor shear modulus measurements of PPS composites if the material has no internal stress cracks. For example, there was no significant difference for in‐plane shear moduli determined from these three shear testsw for the improved, thoughened PPS composites. This was attributed to the thoughness and fast crystallization of the PPS composites. This was attributed to the thoughness and fast crystallization of the PPS matrix resin, and the strong fiber/maxtrix interface, however, the ±45° in‐place shear test should be used with caution for certain thermoplastic composites,. Becuase of the ±45° lay‐up, the annealed[±45]2s original PPS composite la, omates siffered jogj resodia; stresses and were observed to have stress‐related cracks. Consequently, the measured shear moduli are lower than the true values. Since we have demostrated that some shear tests amy not be appropriate for modulus measurements of certain composites, it is important to choose the proper test method for the shear characterization of thermoplastic composites.
Microstructure‐based processing parameters of thermoplastic composite materials. Part II: Experimental results
Authors: Yang Heechun , Colton Jonathan S. 
Published: May 2005

AbstractThe permeability of termoplastic composites and the elastic behavior of their fiber networks were measured during compression molding. As these processing parameters depend on the microstructure of the composite, experiments were performed to determine them for tape prepreg, commingled two repreg, and powder‐coated tow prepreg. The experimental results agree closely when compared to the theoretical predictions.
Three‐dimensional nonisothermal mold filling simulations in resin transfer molding
Authors: Young Wen‐Bin 
Published: May 2005

AbstractThe manufacture of polymer composites through the process of resin transfer molding (RTM) involves the impregnation of the reactive polymer resing into a mold with preplaced fibrous reinforcements. Determination of RTM processing conditions requires the understanding of various parameters, such as material properties, mold geometry, and mold filling conditions. Modeling of the entire RTM process provides a tool for analyzing the relationship of the important parameters. This study developed a nonisothermal 3‐D computer simulation model for the mold filling process of RTM based on the control volume finite element method. The model will be able to simulate mold filing in molds with complicated 3‐D geometry. Results of some numerical studies in RTM show the applications of the proposed model.
Probing morphology and toughening mechanisms of high performance composities using transmission electron microscopy
Authors: Garcia‐Meitin E. I. , Sue H.‐J. 
Published: May 2005

AbstractThe usefulness of the transmission electron microscopy (TEM) technique in probing the morphology and toughening mechanisms of high performance composite systems is demonstrated. TEM provides an effective study of both the morphology and fracture behavior of graphite fiber reinforced epoxy and for cyanate composite systems. The failure process in these composites can be under stood. The TEM technique introduced here is found to be valuable for both fundamental and developmental research in improving both physical and mechanical properties of high performance composites. The present work focuses on demonstrating how a composite can be successfully prepared for TEM investigations. Experimental procedures concerning identification and isolation of the crack tip damage zoen, followed by cutting, trimming, staining, and thin section of the composite sample are detailed.
Fracture and acoustic emission characteristics of glass fiber reinforced plastics panels for hot water
Authors: Morii Tohru , Tanimoto Toshio , Hamada Hiroyuki , Maekawa Zen‐Ichiro , Hirano Takahiro , Kiyosumi Kenji 
Published: May 2005

AbstractThis study deals with the fracture process and acoustic emission (AE) characteristics of a randomly oriented E‐glass fiber mat reinforcement with a crosslinked polyester. These panels were evaluated after they were immersed in hot water. The fiber volume content of the panel was 19%. Glass fiber reinforced plastics (GFRP) panels wer immersed in water at 81°C. Bending and AE monitoring tests were Performed and after bending, the cross‐section of the specimen was observed by an optical microscope and SEM. The influence of degradation, due to water immersion, on the changes of fracture process of GFRP is discussed. The dominant fracture mode of the virgin specimen was matrix cracks, whereas that of the immersed specimen was debondings at the fiber bundle/matrix and fiber/matrix interfaces. This change was caused by reduction of the bonding strength at the interface. The scale of fracture can be estimated by both AE amplitude and AE energy and this estimation method was used to estimate the fracture mode changes of GFRP panels immersed in hot water.
Estimation of the resin flow permeability of fiber tow preforms using the self‐consistent method
Authors: Cai Zhong , Berdichevsky Alexander L. 
Published: May 2005

AbstractThis paper presents a model using the self‐consistent method for estimating the resin flow permeability of fiber tow preforms. The permeable resin is assumed to be a Newtonian fluid, such as an uncured and low viscosity epoxy resin. Permeability in both longitudinal and transverse directions is considered. In the discussion, a basic cell insertion is constructed to include a representative fiber tow surrounded with fluid. The insertion is placed into a homogeneous medium with an unknown permeability. Stokes flow is applied to the fluid region, and Darcy flow is considered at the tow region and in the outside homogeneous medium. Boundary and interface conditions as well as consistent conditions, including the total amount of the flow and the dissipation energy, are applied accordingly. Permeability is solved from these considerations. The prediction expresions using parameters of average fiber volume fraction, tow volume fraction, and tow size are derived. The results show that the main flow paths are the openings or gaps between neighboring tows in both longitudinal and transverse directions. The observation provides a scientific base for the simplification of the problem treatment.
Applications of a fiber orientation prediction algorithm for compression molded parts with multiple charges
Authors: Reifschneider L. G. , Akay H. U. 
Published: May 2005

AbstractAn application of a finite element simulation of mold filling and predication of fiber orientation in fiber filled compression molded parts is presented. Three‐dimensional thin‐walled geometries are considered. Following a simulation of the filling process, a set of transort equations are solved to predict the locally planar orientation of short fiber composites. The final orientation states throughout the part provide the necessary information to obtain a locally orthotropic mechanical model of the composite. A sheet molding compound part with a multiple charge pattern is used to illustrate the generality of the algorithms developed for compression flow, fiber orientation, and property predications. Derivations of the orthotropic mechanical properties obtained from the fiber orientation results are outlined.
Interpretation of 3‐D permeability measurements for RTM modeling
Authors: Woerdeman Dara L. , Phelan Frederick R. , Parnas Richard S. 
Published: May 2005

AbstractThe resin transfer molding (RTM) technique often utilizes reinforcement with a complex fiber architecture. Several parameters, including the permeability tensor, are necessary to characterize the flow behavior in these intricate fibrous porous media. In this paper, a general procedure for extracting three‐dimensional permeability tensors from data is presented. A general procedure is warranted if the permeability tensor lies out of the material plane. An approximate solution to Darcy's law was employed to relate the components of the permeability tensor to experimental measurements. The procedure requires inverting six nonlinear equations with a robust binary search algorithm. The accuracy of the approximate solution to Darcy's law was checked and found to be in close agreement with a nearly exact solution to Darcy's law obtained by finite element methods.
Investigation of the microcracking behavior of bismaleimide composites during thermal aging
Authors: Burcham Loyd J. , Eduljee Rushad F. , Gillespie John W. 
Published: May 2005

AbstractSamples of 16‐ply, quasi‐isotropic bismaleimide composites were aged in convection ovens at 150°C, 177°C, and 204°C for up to 16,000 hours. As a measure of degradation, transverse microcrack density was characterized as a function of time, temperature, and ply depth. Times required to reach onset and saturation crack density were delayed on the tool side of the laminate, for lower temperatures, and for deeper ply depths. Saturation crack densities ranged from 35 cracks/cm to 46 cracks/cm, depending on ply depth. Master curves were constructed for each ply level to express all time‐temperature data for that ply as a single reference curve. A mass transfer analysis further suggests that diffusion is the controlling mechanism in the degradation process. Finally, a prediction of the degradation behavior in the 120,000‐h lifetime of the HSCT aircraft for a sustained temperature of 150°C indicates that ∼13 plies will have reached initiation in a quasi‐isotropic laminate.
Environmental effect on stress relaxation in polyester‐fiberglass composite
Authors: Gutman E. M. , Soncino R. 
Published: May 2005

AbstractEnvironmental behavior of reinforced polyester was studied by stress relaxation. Relaxation failure of polyester matrix and fiberglass degradation appear dramatically at short time after exposure to acid and alkali electrolytes. The relaxation spectrum is thus influenced by environmental action. Indeed, the stress relaxation modulus is a sensitive characterization of environmental effects.
Determination of the packing density of solid polymer chains. Determination of the specific surface area of polymers by sorption of nitrogen vapor
Authors: Tsilipotkina M. V. , Tager A. A. , Petrov B. S. , Pustobaeva G. 
Published: May 2005

AbstractThe sorption of nitrogen vapors on polyethylene, polytetrafluoroethylene, saran, polyvinylalcohol, polyvinylacetate, polystyrene, cellulose and ethylcellulose at the nitrogen boiling point has been investigated. It has been shown that polyethylene, polytetrafluoroethylene, saran, polyvinylalcohol and polyvinylacetate are non‐porous sorbents with dense packing of the macromolecules. It has been shown that the specific surface area of cellulose, ethylcellulose and the total pore volume of polystyrene calculated from nitrogen vapor sorption is less than the corresponding value determined from the sorption of organic substances. Nitrogen vapor sorption at the nitrogen boiling point cannot be used for estimating the porosity of loosely packed polymers.
Some observations on the morphology and fracture characteristics of knit lines
Authors: Hobbs S. Y. 
Published: May 2005

AbstractThe morphology of isotactic polypropylene in molded plaques containing a knit line is described in detail. The effects of mold temperature and flow on the size and orientation of spherulitic and transcrystalline regions are discussed. Deformation at the weld line under uniaxial tensile stress is analyzed by optical microscopy.
The mechanical properties of oriented discontinuous fiber‐reinforced thermoplastics. I. Unidirectional fiber orientation
Authors: Blumentritt Bruce F. , Vu Ban T. , Cooper Stuart L. 
Published: May 2005

AbstractThe mechanical properties of a series of thermoplastics reinforced with unidirectionally oriented short fibers are reported. Both organic and inorganic fiber reinforcements were used in fiber volume fractions of 0.10 to 0.50. A number of these composites were found to have excellent strength and stiffness properties combined with good toughness and low density. The dependence of composite properties on the properties of the constituent materials is discussed. Fiber efficiency factors for strength and modulus are presented and models for predicting composite mechanical behavior are reviewed.
Glass transitions of topologically interpenetrating polymer networks
Authors: Frisch H. L. , Frisch K. C. , Klempner D. 
Published: May 2005

AbstractTwo component topologically‐interpenetrating polymer networks were made of the SIN type (simultaneous interpenetrating network) composed of two polyurethanes (a polyether‐based and a polyester‐based) in combination with an epoxy resin, a polyacrylate and two unsaturated polyesters. The linear polymers and/or prepolymers were combined in solution and in bulk together with the necessary crosslinking agents and catalysts. Films were cast and chains extended and crosslinked in situ. All of the IPN's exhibited one glass transition (Tg) intermediate in temperature to the Tg's of the component networks, and as sharp as the Tg's of the components. This suggests that phase separation may not occur and thus some chain entanglement (interpenetration) of the two networks is involved. The observed Tg's are always several degrees lower than the arithmetic means of the component Tg's. A theory based on interpenetration is developed to account for this.
End corrections in the capillary flow of polystyrene melts
Authors: Hyun Kun Sup 
Published: May 2005

AbstractThe origin of the discrepancy between the Bagley method and the modified method suggested by Han in obtaining the end correction data is traced to the effect of a deviatoric stress contribution in the pressure measurement at the capillary wall. The end correction factors for polystyrene melt were obtained by the Bagley method. The effects of temperature, die entry angle, contraction ratio or reservoir diameter‐to‐die diameter ratio are discussed.
Effect of molecular weight on rate of enthalpy relaxation of poly (methyl methacrylate) and its oligomers
Authors: Yoshida Hirohisa , Kobayashi Yasuji 
Published: May 2005

AbstractThe enthalpy relaxation process of methyl methacrylate oligomers and poly (methyl methacrylate) was analyzed by use of the excess enthalpy (ΔHt), which was obtained from a differential scanning calorimetric measurement. The apparent relaxation time (τ½) was estimated by the assumption of the single relaxation time response. The Tg of oligomers increased with an increase of molecular weight, and approached a constant value above 1 × 104. The apparent relaxation time showed a similar molecular‐weight dependency as Tg, and approached a constant value above 1 × 104. It was expected that the molecular motion which caused the enthalpy relaxation was based on the segmental motion of main chains.
A breakthrough to the plasma deposited dry‐developable e‐beam resist
Authors: Hattori Shuzo , Morita Shinzo , Yamada Masao , Tamano Junji , Ieda Masayuki 
Published: May 2005

AbstractThis paper presents the preliminary results of efforts to improve dry processed electron beam resist materials using plasma polymerization coating technology. Three approaches investigated were chemical susceptibility modification, the use of multilayer resist structures, and the effect of grafting reactions.