bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interface modification and characterization in three‐component polymer blends
Authors: Fisher I. , Zoldan J. , Siegmann A. , Narkis M. 
Published: April 2004

AbstractThe effect of interface characteristics on the properties of three‐component polymer blends comprising PP/EVOH/mica and PP/EVOH/glass beads (GB) was investigated (polypropylene‐PP, ethylene‐vinylalcohol‐EVOH). The systems selected are based on the binary PP/EVOH immiscible blend representing a semi‐crystalline apolar polymer (PP) and a semi‐crystalline highly polar copolymer (EVOH), where PP serves as the matrix. A series of the binary and three‐component blends with varying compositions was chosen to study the effect of the molding procedure, i.e. compression versus injection molding. The structures observed by SEM analysis consisted of the filler particles engulfed by the EVOH phase, with some of the minor EVOH component dispersed within the PP matrix. The effects of silane treatment (GB/EVOH interface) and compatibilization, using a maleated‐PP compatibilizer (PP/EVOH interface), were studied in relation to the generated structured and properties. The compatibilizer was added in a unique procedure by which the encapsulated GB/EVOH structures were preserved. The characterization methods used included morphology by Scanning Electron Microscopy, thermal properties and crystallization behavior by Differential Scanning Calorimetry, mechanical properties by tensile testing, and dynamic characteristics by Dynamic Mechanical Thermal Analysis. The work has shown that structure‐performance relationships in the three‐component blends can be varied and controlled.
Mechanical properties of glass fiber/organic fiber mixed–mat reinforced thermoplastic composites
Authors: Kitano T. , Haghani E. , Tanegashima T. , Saha P. 
Published: April 2004

AbstractThe purpose of this study is to investigate the influence of different types of fibers on the mechanical properties of hybrid composite materials. Long and short glass fibers (GF) and different types of organic fibers, viz. aramid fiber, DuPont Kevlar‐49 (KF), liquid crystalline polymer (LCP), and vinylon (VF) in hybrid composites, were used to reinforced the high density polyethylene (HDPE) matrix. The long fiber hybrid composites were prepared in a “fiber separating and flying machine,” while the short fiber hybrid composites were prepared in an “elastic extruder.” The total amount of fibers used in both long and short fiber hybrid composites was fixed at 20 vol%. The influence of fiber content, length, and mixing ratio on mechanical properties, such as tensile, bending, Izod and high rate impact strength, as well as viscoelastic propertics in the solid state, was studied. Fracture surfaces of the materials were also examined using a scanning electron microscopy.
Swirl mat– and long discontinuous fiber mat–reinforced polypropylene composites—status and future trends
Authors: Karger‐Kocsis J. 
Published: April 2004

AbstractPolypropylene (PP) composites with glass and natural fiber mat reinforcement (GMT‐PP and NMT‐PP, respectively) are widely used in different applications, competing with metallic sheets and thermoset polymer composites. Their production occurs via melt impregnation, slurry deposition and various textile architecturing processes that lead to either consolidated or non‐consolidated preforms. These preforms are then converted into final parts by hot pressing. The “traditional” GMT‐PP composites are nowadays faced with a great challenge because of the introduction of long fiber reinforced thermoplastic (LFT) composites produced on‐ or off‐line. This paper gives a brief survey on the manufacturing, processing, properties and application of GMT and GMT‐like systems and it concludes by describing some of the future trends, especially in the fields of material and process developments.
Stamping of continuous fiber thermoplastic composites
Authors: Chen Julie , Sherwood James A. , Buso Patricia , Chow Samuel , Lussier Darin 
Published: April 2004

AbstractDespite demonstrated success in low volume aerospace and defense applications, structural composites remain at the periphery of high volume industries such as construction, automotive, and consumer goods because of long cycle times. Stamping provides a means of making composite sheet products at rates ten to a hundred times faster than any existing continuous fiber processes. However, to make composites stamping a viable process, one must understand how the combination of fabric architecture, tool design, and process conditions interact to produce a part free of wrinkling and tearing. In this paper, the effect of temperature, stamping rate, and boundary constraints on the material deformation is presented. The focus of this study is a co‐mingled glass/polypropylene fabric, in the form of a layer of unidirectional yarns held together by stitches. The results show that temperature variations have the greatest effect on deformation. In addition, a finite element model of parallel strips with linear constraints was shown to successfully simulate the sliding deformation or draw‐in of the stitched unidirectional material.
Manufacture of fiber‐reinforced composites by microwave assisted pultrusion
Authors: Methven J. M. , Ghaffariyan S. R. , Abidin A. Z. 
Published: April 2004

AbstractA brief review of the potential for microwave heating in the manufacture of fiberreinforced composites is presented, with particular emphasis on the Microwave Assisted Pultrusion (MAP). Manufacture of a 6 mm cylindrical glass reinforced profile, based on a number of latent‐cure epoxy resins by MAP is described. These materials combine room temperature stability (long pot life) with rapid crosslinking at elevated temperature. The measured line speeds exceeded 2 m/min, using approximately 800 W of applied microwave power in a single mode TM010 cavity operating at 2450 MHz. The measured pulling force was about 250 N, showing a stick‐slip behavior for a crosslinked profile. The ultimate tensile strength and the interlaminar shear strength of the profiles increased after post curing, suggesting that the extent of crosslinking in the MAP die may be diffusion limited.
Processing and properties of injection molded thermoplastic composites reinforced with melt processable glasses
Authors: Young R. T. , Baird D. G. 
Published: April 2004

AbstractThis work was concerned with evaluating the properties of injection molded composites comprising polyetherimide (PEI) and polyetheretherketone (PEEK) reinforced with various lower Tg melt processable phosphate glasses. Composites were produced utilizing a variety of glass and resin combinations in order to ascertain the effects of factors such as glass concentration and viscosity of the components on the mechanical properties of the composite blends. Changes in the rheological and interfacial properties of the blends obtained by varying the resins and phosphate glasses used during processing resulted in a variety of reinforcing morphologies consisting of glass beads, ribbons, and an interpenetrating network structure. The large variations in the glass phase morphologies obtained during injection molding led to composites that displayed a wide range of properties. Generally, it was found that the use of resin/glass combinations that minimized the viscosity difference between the components resulted in composites displaying the best overall mechanical properties. The stiffness of the composites was found to increase with glass concentration with loadings up to 45 vol% glass, leading to moduli 3‐4 times greater than those of the neat resins. While the addition of the phosphate glasses produced significant enhancements in the stiffness of the composite blends, the strength often fell to values 2‐3 times lower than those of the neat resins.
A simplified in‐plane permeability model for textile fabrics
Authors: Yu Boming , James Lee L. 
Published: April 2004

AbstractIn this paper, a simplified in‐plane permeability model for textile fabrics is developed. The model is based on a rectangular unit cell geometry, the one‐dimensional Stokes equation for flow in the channels or gaps between fiber tows, and the one‐dimensional Brinkman equation for flow in fiber tows. Three different textile fabrics are considered in the model: plain woven, 4‐harness, and bidirectional stitched fiberglass mats. The model incorporates the effect of porosity changes on permeability of fiber preforms under compression, which usually occurs in the molding process. To verify the validity of the model, the theoretical values are compared with a set of permeability measurements. Good agreement is found between the model prediction and the permeability measurements in the porosity ranges of ϕ ≤ 0.59 for plain woven fiber mats, ϕ ≤ 0.60 for 4‐harness fiber mats and ϕ ≤ 0.62 for bidirectional stitched fiber mats.
A phenomenological study of the mechanical properties of long‐fiber filled injection‐molded thermoplastic composites
Authors: Stokes V. K. , Inzinna L. P. , Liang E. W. , Trantina G. G. , Woods J. T. 
Published: April 2004

AbstractTensile and flexural tests on specimens cut from rectangular injection‐molded plaques show that long‐fiber filled thermoplastic composites are complex, non‐homogeneous, anistropic material systems. Like all fiber‐filled materials, they exhibit through‐thickness nonhomogeneity as indicated by differences between tensile and flexural properties. The in‐plane orientation of fibers in through‐thickness layers causes the material to have in‐plane anisotropic properties. However, these long‐fiber filled materials exhibit an unexpectedly large level of in‐plane nonhomogeneity. Also, the effective mechanical properties of these materials are strongly thickness dependent. The thinnest plaques exhibit the largest differences between the flow and cross‐flow tensile properties. These differences decrease with increasing thickness. A methodology for part design with this class of materials is discussed.
Commingled poly(butylene terephthalate)/unidirectional glass fiber composites: Influence of the process conditions on the microstructure of poly(butylene terephthalate)
Authors: Vendramini J. , Bas C. , Merle G. , Boissonnat P. , Alberola N. D. 
Published: April 2004

AbstractThe microstrocture of poly(butylene terephthalate) (PBT) has been investigated at the different stages of the manufacture of a new generation of composite materials, i.e., commingled Twintex® PBT/glass fiber composites. From differential scanning calorimetry and wide angle X‐ray scattering analysis in addition to density measurements and optical microscopy observations, it was concluded that the different stages of the composite manufacture induce some changes in the crystalline forms of PBT. In particular, the drawing of PBT can promote the formation of the β phase. The analysis of the crystallization kinetics points out the nucleation role played by the fibers. It is concluded that the growth of a transcrystalline region in the vicinity of fibers is promoted by the elevated pressure and temperature used in the manufacturing process of the composites.
Morphological development during injection molding of self‐reinforcing composites. I: Experimental results
Authors: Narh Kwabena A. , Li Zhigang 
Published: April 2004

AbstractThe correlation between structure development during injection molding and the modulus of injection molded PET/LCP blends were studied. Process parameters such as injection speed and mold and melt temperatures were varied to determine the effect of these parameters on the tensile modulus and structure development of the blends. The skin/core structure in the cross section of injection molded samples was observed with both optical and scanning electron microscopy techniques. Injection molding experiments show that the thickness of the skin layer increases with decreasing injection speed and decreasing melt and mold temperatures. The trends in morphological developments in the injection molded specimens correlate with the measured tensile moduli.
Numerical and experimental analysis of resin flow and cure in resin injection pultrusion (RIP)
Authors: Ding Zhongman , Li Shoujie , Yang Huan , James Lee L. , Engelen Herbert , Puckett P. M. (Mac) 
Published: April 2004

AbstractThis work presents the results of modeling, numerical simulation, and experimental study of resin flow and heat transfer in the resin injection pultrusion (RIP) process. A control volume/finite element method (CV/FEM) was used to solve the flow governing equations, together with heat transfer and chemical reaction models. Resin viscosity, degree of cure, and fiber stack compressibility and permeability were measured in order to understand their influences on the process. An analytical flow model has also been develped based on the one‐dimensional flow approximation for the resin flow in the injection die. A high‐pressure small‐taper injection die was tested with different line speeds. Experimental data were used to verify the simulation results and the analytical solutions.
Toughening of epoxy/polycaprolactone composites via reaction induced phase separation
Authors: Siddhamalli Sridhar K. 
Published: April 2004

AbstractA series of melt processable thermoset/thermoplastic blends were prepared by mixing bisphenol‐A diglycidyl ether (Epon‐828)/diaminodiphenyl sulfone (DGEBA/DDS) system with two grades of polycaprolactone resin. Phase separation behavior of the blends was investigated by means of optical microscopy, microstructure by scanning electron microscopy (SEM), and thermo‐mechanical properties. The toughness of polycaprolactone modified epoxies was measured by instrumented falling weight impact (IFWI) testing. Various blend morphologies were observed depending upon the cured epoxy network/thermoplastic composition. Spinodal decomposition as characterized by modulated structure of unique periodicity and phase connectivity was found to be the probable mechanism of phase separation. SEM examination of fracture surfaces indicated a strong adhesion between the epoxy‐rich and polycaprolactone‐rich phases. Optimum improvement in failure energy was obtained for the compositions containing 10‐20% polycaprolactone without significantly compromising the elastic modulus and the thermo‐mechanical stability of the epoxy. In light of morphological evidences, a possible toughening effect was postulated in terms of tearing of the thermoplastic component and induced plastic deformation of the epoxy matrix.
Relaxation of the axial strain induced stresses in double–coated optical fibers
Authors: Shiue Sham‐Tsong 
Published: April 2004

AbstractThe axial strain induced stresses in double‐coated optical fibers are analyzed by the viscoelastic theory. A closed form solution of the axial strain induced viscoelastic stresses is obtained. The viscoelastic stresses are a function of the radii, Young's moduli, relaxation times and Poisson's ratios of the polymeric coatings. If the applied axial strain linearly increases, the induced stresses increase with the time. On the other hand, if the axial strain is fixed, besides the axial stress in the glass fiber, the stresses exponentially decrease with the time. The relaxation of stresses is strongly dependent on the relaxation times of the polymeric coatings. If the relaxation time of the polymeric coating is very long, the viscous behavior of the polymeric coatings will not appear, and the axial strain induced stresses solved by the viscoelastic theory are the same as those solved by the elastic theory. On the other hand, if the relaxation time of the polymeric coating is very short, the relaxation of stresses is very apparent. A compressive radial stress at the interface of the glass fiber and primary coating will result in an increase of the transmission losses, and a tensile interfacial radial stress will possibly produce debonding at the interface of the glass fiber and primary coating. To minimize this interfacial radial stress, the radius, Young's modulus and Poisson's ratio of the polymeric coatings should be appropriately selected, and the relaxation time of the primary coating should be shortened. Finally, the stresses in single‐coated and double‐coated optical fibers are discussed.
Morphology and mechanical properties of direct injection molded polypropylene/thermotropic copolyester blends
Authors: Guerrica‐Echevarría G. , Eguiazíbal J. I. , Nazíbal J. 
Published: April 2004

AbstractBlends of two grades of polypropylene (PP) with thermotropic copolyester (Rodrun) contents of up to 40% were obtained by direct injection molding at different processing temperatures. In the skin of the molded specimens rather long fibers were seen in blends with low‐viscosity PP, whereas sheets were found when the high‐viscosity PP was the matrix. In the core, the viscosity of the matrix played a more relevant role than the viscosity ratio on the orientation level of the dispersed Rodrun phase. The better mechanical properties of the blends with the low viscosity PP are attributed to the morphology change of the dispersed phase from sheets to fibers when the viscosity of the matrix decreased.
Properties and interfacial bonding for regenerated cellulose–polyurethane/amylose acetate sipn composite films
Authors: Yu Jiahui , Du Yumin , Zheng Hua , Cheng Fangyu 
Published: April 2004

AbstractComposite films were obtained by placing a polyurethane/amylose acetate semi‐interpenetrating polymer network (SIPN) coating onto the surfaces of regenerated cellulose (RC) film. The properties of the composite film, such as tensile strength, 79.9 MPa (in dry state), 49.5 MPa (in wet state), water resistance (R), 0.62, dimensional stability (Sc), 3.0%, and water vapor permeability (P), 5.96 × 10−5 Kgm−2h−1, are better than those of the uncoated RC film or RC film with PU coating. The interfacial strength was characterized with infrared spectroscopy (IR), ultraviolet spectroscopy (UV), transmission electron microscopy (TEM), and electron probe microanalysis (EPMA). The results showed the existence of covalent and hydrogen bonds between the SIPN coat layer and the RC layer. It was also found that the PU prepolymer in the coating layer penetrated into the cellulose bulk, and reacted with the cellulose molecules, which formed another SIPN.
Damage evolution in low velocity impacted unreinforced vinyl ester 411‐350 and 411‐C50 resin systems
Authors: Motuku M. , Janowski G. M. , Vaidya U. K. , Hosur M. V. , Mahfuz H. , Jeelani S. 
Published: April 2004

AbstractDamage evolution in plaques made of vinyl ester resin systems was investigated as a function of specimen thickness, impact energy level and matrix material. Dow DERAKANE vinyl ester 411‐350 and 411‐C50 resin systems, which have low viscosity and are ideally suited for low‐cost liquid processing techniques like vacuum assisted resin transfer molding (VARTM), were considered for the low velocity instrumented impact testing. Characterization of damage evolution was undertaken using optical microscopy and analysis of impact load histories recorded during the impact event. Radial cracking, perforations at the point of impact (in the form of a truncated cone), and damage resulting from the support constraints were identified as the dominant failure characteristics in both resin systems. Radial cracking, which originated from the bottom surface, was operative in all failed specimens and was attributed to the catastrophic failure due to extensive flexural tensile strength losses. For specimens that could deflect significantly, radial cracking and support‐constraint‐induced damage were the operative failure mechanisms. Radial cracking and through‐thickness shearing led to failure in stiffer plaques. The DERAKANE 411‐350‐vinyl ester resin system was found more damage resistant than the 411‐C50 system.
Extensional processing behavior of thermoplastics reinforced with a melt processable glass
Authors: Young R. T. , McLeod M. A. , Baird D. G. 
Published: April 2004

AbstractThis work was concerned with investigating the processing behavior of thermoplastics reinforced with a melt processable phosphate glass under extensional flows at temperatures used for forming and shaping operations. Injection molded blends consisting of polyetherimide (PEI) and polyphenylene sulfide (PPS) reinforced with 30‐60 wt% phosphate glass were exposed to uniaxial and planar deformation at temperatures above the Tg of the phosphate glass (234°C) to evaluate the effects on the morphology and mechanical properties of the composites. Tensile testing at elevated temperatures (250‐300°C) was used to evaluate the forming behavior and ascertain the conditions most suited for the deformation of the composite blends. A temperature approximately 35°C above the Tg of the P‐glass was found to offer conditions most conducive to the deformation of the PEI/P‐glass blends. The phosphate glass reinforced PEI was found to offer greater retention of properties and smoother surfaces than an E‐glass filled material when exposed to shearfree deformation similar to that seen in a process such as thermoforming. For PPS based composites, the application of planar shearfree deformation near the melting point of the PPS (≈︁ 283°C) resulted in the elongation of the phosphate glass phase which served to enhance the stiffness of the composite blends along the principal deformation direction.
Material systems for rapid manufacture of composite structures
Authors: Kinard Janet , Colton Jonathan 
Published: April 2004

AbstractA manufacturing process is described that builds complex composite parts using a layered building process in which each layer of pre‐preg composite is laid and cured as the build progresses. In order to employ on‐line curing without molds, resin technologies that provide fast curing at room temperature—ultraviolet curable and epoxy/polyamide—were investigated. UV‐curable resins were tested for their ability to “shadow” cure by exposing carbon fiber composites to ultraviolet light to determine if the cure propagated from areas directly exposed to areas under fibers. Though ultraviolet curing showed advantages in cure time and low volatile production, very minimal “shadow” curing was achieved. A low temperature curing epoxy/polyamide mixture was tested for the effects of cure temperature, cure time, and mix ratio on the final degree of cure (%DOC) and glass transition temperature (Tg). Layers were made using different resin mixtures, partially cured, and used to build layered parts to determine curing characteristics during the lay‐up process. In the epoxy/polyamide mixtures, mix ratio had little effect on the reaction rate but did affect the Tg. A kinetic model was established for the resin epoxy/polyamide system for optimizing processing conditions during fabrication. However, the model failed to correctly predict the fabrication. The reaction of the material was different during the fabrication process than during the isothermal cure due to the presence of oxygen. During the build process, the degree of cure in each layer increased significantly over the prestaged degree of cure in less time than theoretically predicted. However, the final resin properties, such as Tg, were still below the specifications for high performance parts.