bluuebunny/crossref_metadata_2025_split huggingface dataset:
Processability and mechanical properties of ternary composites PP/EPDM/GF
Authors: Barbosa Silvia E. , Capiati Numa J. , Kenny José M. 
Published: April 2004

AbstractThe enhancement of the mechanical properties of neat PP is achieved by the addition of glass fibers and EPDM rubber. The Young's modulus and notched Charpy impact strength of the composites obtained are improved with respect to the original polymer, leading to a new composite material with a very good balance of toughness and rigidity properties. The tensile behavior of these multiphase systems is successfully compared with theoretical predictions using the Halpin‐Tsai/Nielsen theory for uniaxially short fiber composites, which considers the matrix as a blend with spherical particles and can predict the tensile modulus considering an average fiber orientation angle. An accurate morphological study performed by scanning electron microscopy (SEM) shows a very good dispersion of the rubbery phase into the neat matrix. No special affinity between the rubber and the fibers is reported. The good dispersion and the small particle diameter indicate the good processability of the ternary systems studied.
Chemical modification and adhesion in carbon fiber/epoxy micro‐composites; coupling and surface coverage
Authors: Földes Enikő , Gulyás János , Rosenberger Stefánia , Pukánszky Béla 
Published: April 2004

AbstractFour compounds were used to improve adhesion between carbon fibers and an epoxy matrix. Triglycidyl isocyanurate (TGIC) and 3‐glycidoxy‐propyl‐triethoxysilane (EPS) contained reactive epoxy groups, while N‐(3‐trimethoxysilane‐propyl)ethylene diamine (AMS) a primary and a secondary amino group. The fourth coupling agent was 4,4' diphenylmethane‐diisocianate (MDI). The interaction of the fiber and the coupling agents was studied by dissolution experiments. Chemical reactions taking place on the surface of the fiber were followed by FTIR spectroscopy. Interfacial shear stress determined by fragmentation was used for the characterization of matrix/fiber adhesion. Beside coupling to the surface, EPS, AMS and MDI formed a polymer layer on the surface, but TGIC also entered into secondary reactions during the treatment. Both the type and the amount of the coupling agent affects strongly interfacial adhesion, which is determined by the thickness and properties of the formed coupling agent layer. The combination of dissolution experiments with the fragmentation test yields valuable information about the processes taking place on the surface of the fiber, facilitate the selection of the best coupling agent, as well as the development of surface treatment technology.
Structure development in thermoset recyclate‐filled polypropylene composites
Authors: Bream C. E. , Hornsby P. R. 
Published: April 2004

AbstractPolypropylene containing comminuted fiber reinforced thermoset recyclate has been shown to exhibit enhanced mechanical properties relative to particulate‐filled materials. Optimum mechanical performance in these recyclate‐filled materials is achieved in compositions made from rubber‐modified polypropylene containing maleic anhydride‐modified PP in conjuction with silane coupling agent. Although matrix crosslinking was found to enhance properties in both filled and unfilled systems, composite properties are dominated by the development of strong interfacial bonding between polypropylene and recyclate reinforcement. A mechanism for the formation of interfacial bonding is proposed involving reaction between maleic anhydride functionalized PP, formation of trisilanol groups and their subsequent condensation with hydroxyl groups on the recyclate surfaces, together with molecular entanglement and co‐crystallization of the grafted and ungrafted polypropylene molecules. Furthermore, in the absence of treatment there is evidence that the elastomer particles encapsulate the filler particles. However, this effect is strongly hindered when functionalized‐PP is added, either in isolation or in combination with the silane co‐treatment. The crystalline nucleation of PP by thermoset recyclate and treatment is also considered. The treatment system investigated was found to promote interfacial bonding to both the polyester (DMC) and woven glassreinforced phenolic recyclates investigated, suggesting it may be suitable for treating mixed composite scrap.
Sensor placement study for online flow monitoring in liquid composite molding
Authors: Kueh Sylvia R. M. , Advani Suresh G. , Parnas Richard S. 
Published: April 2004

AbstractOn‐line sensing can play an important part in controlling the quality of the final product in any manufacturing environment, including liquid composite molding (LCM). Having a sensor embedded within the part itself is often the most effective means of monitoring its condition at various stages of manufacturing and even throughout its useful life. However, given their intrusive nature, there are practical limitations imposed upon their size, quantity and trajectory within the part. This study explores the possibility of using a single lineal sensor to monitor the resin flow front during the mold filling stage of LCM, and to detect the onset of void formation and the presence of dry spots within the mold. Experiments were conducted to characterize the response of a fiber optic system previously developed for cure monitoring. Simulations were then performed to determine the optimal placement of just one such sensor in a mold to demonstrate that sufficient information on the mold filling process could be obtained. The purpose of the simulation work was to learn how to interpret the sensor response and, subsequently, use it to control the LCM process.
E‐Glass/DGEBA/m‐PDA single fiber composites: The effect of strain rate on interfacial shear strength measurements
Authors: Holmes G. A. , Peterson R. C. , Hunston D. L. , McDonough W. G. 
Published: April 2004

AbstractPrecise measurements of fiber break regions have been made during the single fiber fragmentation test (SFFT) procedure on E‐glass/diglycidyl ether of bisphenol‐A (DGEBA)/meta‐phenylenediamine (m‐PDA) test specimens. From these measurements, the location and size of each fiber fragment was determined, and the resulting information was used to construct fragmentation maps of the tested fiber. By comparing these maps, the fragmentation process supports random fragmentation along the length of the fiber. Since the interfacial shear strength (IFSS) or the interfacial shear stress transfer coefficient (I‐STC) is obtained from the fragment length data at the end of the test (saturation), frequency histograms of the fragment length data were constructed to determine the repeatability of the fragmentation process. Since the SFFT is performed by sequential step‐strains of the test specimen, test protocols were developed by controlling the step size of each strain increment and the time between each step‐strain (dwell time). For the testing protocols used in this research, the E‐glass/DGEBA/m‐PDA frequency histograms of the fragment lengths were found to be generally repeatable. However, when the effective strain rate of the test was altered by changing the dwell time between strain increments, the fragment distribution at saturation of the E‐glass/DGEBA/m‐PDA SFFT specimens changed. The direction of the change was found to be inconsistent with the effect one might expect when only the nonlinear viscoelastic behavior of the matrix is considered. However, the magnitude of the change observed in the E‐glass/DGEBA/m‐PDA SFFT specimens is not universal. Fragmentation data obtained on E‐glass/polyisocyanurate SFFT specimens revealed a much smaller change in fragment length distributions with the same change in testing protocols. Consistent with the results obtained on the E‐glass/DGEBA/m‐PDA, fiber fragmentation occurs when the polyisocyanurate matrix exhibits nonlinear viscoelastic behavior. The implication of these results for interfacial shear strength measurements is discussed.
Nondestructive evaluation methods for damage assessment in fiber‐metal laminates
Authors: Fahr A. , Chapman C. E. , Forsyth D. S. , Poon C. , Laliberté J. F. 
Published: April 2004

AbstractThe Structures, Materials and Propulsion Laboratory of the NRC Institute for Aerospace Research (IAR) is engaged in a collaborative project with Bombardier Aerospace. The main objective of the project is to evaluate the potential of applying fiber‐metal laminates (FML) to aircraft types manufactured by Bombardier. As a part of this project, nondestructive evaluation (NDE) procedures have been developed and used at IAR to determine the extent of damage caused by impact, corrosion and fatigue loads in a commercial FML material (GLARE). X‐rays using radioopaque fluids as well as conventional and air‐coupled ultrasonic and eddy current methods have been investigated. This report describes the NDE procedures employed at IAR to assess damage in FML and provides examples of the results obtained utilizing each of the inspection methods and the damage types investigated. Also, the ability of the investigated NDE methods to determine damage size and the accuracy of damage measurements is discussed.
Polyester cure monitoring by means of different techniques
Authors: Ton‐That M.‐T. , Cole K. C. , Jen C.‐K. , França D. R. 
Published: April 2004

AbstractThe cure of a set of polyester resin samples having different styrene contents has been monitored by means of Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), rheometry, and ultrasonic measurements. FTIR and DSC experimental data were used to calculate the cure kinetics using a freeradical polymerization model (multiple steps) and also an empirical model that considers the curing to involve only a single step. The dependence of viscosity on the degree of curing has been investigated at different shear rates. Finally, correlations among the results from the different techniques have been established and discussed in terms of the curing mechanism.
Electron beam curing of polymer composites
Authors: Raghavan J. , Baillie Mark R. 
Published: April 2004

AbstractElectron‐beam (E‐Beam) curing of an epoxy polymer matrix and its composite (reinforced with IM7 Carbon fibers) was studied using a cationic photoinitiator. Photoinitiator concentration, dose, and process temperature were varied to understand their influence on E‐beam curing. Optimal photoinitiator concentration was found to be 5 phr. The curing was due to a primary α reaction with a strong dependence on dose, and a secondary β reaction with a weak dependence on dose and a strong dependence on initiator concentration. The extent of cure increased rapidly with dose until 100 kGy and it approached a plateau value beyond 100 kGy. This plateau value corresponded to incomplete curing by 27% for resin and 22% for composite at a process‐temperature of 22°C. The causes for incomplete curing appear to be the secondary β reaction and diffusional limitation. Increase in process temperature resulted in higher extent of cure at a dose level. The material used in this study was also found to be thermally curable and the reaction onset temperature (measured in a DSC ramp experiment) reduced from about 150°C at 0 kGy to about 50°C at 30 kGy. This indicates that simultaneous thermal curing during E‐beam curing of resin and composite is possible. After thermal post‐curing, the Tg of the E‐beam cured resin increased from 130°C at 200 kGy to a value greater than 370°C and the modulus decreased by 10%. The service temperature and the modulus of the 100% thermally cured resin and the thermally post‐cured (after E‐Beam irradiation) resin were comparable.
Surface quality characterization of textile‐reinforced thermoplastics
Authors: Neitzel M. , Blinzler M. , Edelmann K. , Hoecker F. 
Published: April 2004

AbstractTo allow cost effective mass production of reinforced thermoplastics for visible parts, in‐situ a surface quality with “Class‐A” standard must be achieved. Furthermore, after the application of varnish, an appearance (gloss, waviness, color) similar to that of the traditional metal component is required. Porosity and fiber readout are the common surface defects. Fiber readout results from the significantly higher volume shrinkage of the thermoplastic resin (higher CLTE) in comparison to that of the reinforcement during the cooling process in production combined with the uneven distribution of resin and fibers. While glass mat reinforced thermoplastic (GMT) parts show a disorderly readout influenced (among other factors) by fiber length, processing and fiber content of the semi‐finished material, the fabric reinforced thermoplastics (organic sheets) suffer from a regular print‐through—a display of the textile reinforcement. Modern tools of measurement enable one to quantify gloss, roughness, and waviness of the surfaces. Thus parameters significantly influencing the surface characteristics can be identified. This leads to the development of procedures for improving the surface quality.
The hierarchical structure and flexure behavior of woven carbon fiber epoxy composite
Authors: Elleithy Rabeh H. 
Published: April 2004

AbstractThe hierarchical structure and flexure behavior of woven carbon fibers epoxy composite were investigated in this work. First, the hierarchical structure of the composite is characterized on three levels: composite, ply, and yarn. Structura imperfections,In this paper, “structural imperfections” is used to describe the inherent structural characteristics of the actual composite, which deviate from the theoretically ideal and perfect composites, control, that are used in composite theories.
such as, ply‐ply misalignment, ply‐ply offset, and resin pockets, are identified and described. Second, a four‐point bending arrangement is used to study the flexure properties of the composite. Additionally, in‐situ traveling microscope and acoustic emission (AE) techniques are utilized to gain insight to the failure proceses during flexure test. AE showed early stages of matrix cracking before visual observation, which makes it a valuable tool for early failure detection.
Composition dependence of the magnetic properties of bonded magnets of strontium hexaferrite‐polyvinyl chloride
Authors: Matutes‐Aquino J. , Ríos‐Jara D. , Ayala‐Valenzuela O. , Sifuentes Gallardo P. , Ramos De Valle L. F. , Rodríguez Fernández O. S. 
Published: April 2004

AbstractA systematic study of the magnetic properties of strontium ferrite‐polyvinyl chloide plastoferrites as a function of composition is presented. Plastoferrites were manufactured by hot compression of a mixture of commercial powders of strontium ferrite (SrFe12O19) and polyvinyl chloride. In order to explain the dependence of the volumetric density and the saturation magnetization with composition, an additive model for these properties is considered. The intrinsic coercivity shows a decrease with increasing strontium ferrite content, which is interpreted as a magnetizing‐like effect due to the increasing interaction between the magnetic particles. The maximum energy products are lower than 1 MGOe and increase with the second power of the strontium ferrite content. The best maximum energy product and specific saturation magnetization were obtained for the plastoferrite with a 85 weight percentage of ferrite.
Mechanical properties of E‐glass fiber reinforced siliconized epoxy polymer composites
Authors: Alagar M. , Thanikai Velan T. V. , Ashok Kumar A. 
Published: April 2004

AbstractSiliconized epoxy‐matrix systems have been developed by an interpenetrating mechanism using epoxy resins GY 250 and LY 556 (Ciba‐Geigy) and hydroxyl terminated polydimethylsiloxane with γ‐aminopropyltriethoxysilane as crosslinker in the presence of dibutyltindilaurate catalyst. Aliphatic amine (HY 951, Ciba‐Geigy), aromatic amine (HT 972, Ciba‐Geigy) and polyamidoamine (HY 840, Ciba‐Geigy) are used as curing agents for epoxy resins. The tentative level of 10% siloxane introduction into epoxy resin has been ascertained from experimental studies to obtain reasonable improvements in the impact behavior without compromising other mechanical properties. The impact behavior of E‐glass reinforced composites made from the siliconized epoxy resin is enhanced to 2–4 times over that measured on the composites made from a pure epoxy resin. Composites cured with aromatic amine impart better mechanical properties than those cured with aliphatic amine and polyamidoamine.
The influence of crystallinity on interfacial properties of carbon and SiC two‐fiber/polyetheretherketone (PEEK) composites
Authors: Park Joung‐Man , Kim Dae‐Sik 
Published: April 2004

AbstractThe influence of the degree of crystallinity on interfacial properties in carbon and SiC two‐fiber reinforced poly(etheretherketone) (PEEK) composites was investigated by the two‐fiber fragmentation test. This method provides a direct comparison of the same matrix conditions. The tensile strength of the PEEK matrix and the interfacial shear strength (IFSS) of carbon or SiC fiber/PEEK exhibited the maximum values at around 30% crystallinity, and then showed a decline. The tensile modulus increased continuously with an increase in the degree of crystallinity. Spherulite sizes in the PEEK matrix became larger as the cooling time from the crystallization temperature increased. Transcrystallinity of carbon fiber/PEEK was developed easily and more densely than with SiC fiber/PEEK. This might have occurred because the unit cell dimensions of the crystallite in the fiber axis direction on the carbon surface was more suitable for making nucleation sites. The IFSS of carbon fiber/PEEK was significantly higher than that of SiC fiber/PEEK because it formed transcrystallinity of IFSS more favorably.
Fatigue life prediction of matrix dominated polymer composite materials
Authors: Lee C. S. , Hwang W. 
Published: April 2004

AbstractFatigue life prediction is investigated analytically for matrix dominated polymer composite laminates having nonlinear stress/strain response, based on the fatigue modulus concept. Fatigue modulus degardation rate at any fatigue cycle was assumed as a power function of number of fatigue cycles. A new stress function describing the relation of initial fatigue modulus and elastic modulus was used to account for material non‐linearity at the first cycle. It was assumed that fatigue modulus at failure is proportional to the applied stress level. A new fatigue life prediction equation as a function of applied stress is proposed. The prediction was verified experimentally using cross‐ply carbon/epoxy laminate (CFRP) tube under torsional fatigue loading. It is shown that the proposed equation has wide applicability and agrees well with experimental data.
Thermotropic liquid crystal polymer fabric reinforced polyimide composite materials
Authors: Kim Seong Hun , Lim Dong Keun , Yi Sung Chul , Oh Kyung Wha 
Published: April 2004

AbstractAn aromatic copolyeste thermotropic liquid crystal polymer (LCP) fabric was used to reinforce a polyimide (PI) matrix to produce composites. The LCP/PI composite was made to eliminate directional difference in the mechanical properties of LCP by controlling the individual reinforcement fabric alignment in different directions without losing any mechanical properties. As a result, a transversely isotropic LCP composite material could be obtained from the highly anisotropic LCP fiber. Interfacial adhesion between the LCP and polyimide was greatly improved by a NH3/H2 plasma treatment on the LCP fabric, thereby the significantly improving mechanical properties of the composite. Moreover, inter‐laminar shear strength of the LCP/PI composite was further increased after heat treatment at 220°C for 1 hour. The LCP/polyimide composite retains stable mechanical properties up to 250°C.
Comparison of the roles of two shrinkage‐controlled low‐profile additives in water aging of polyster resin–glass fiber composites
Authors: Camino G. , Ya. Polishchuk A. , Luda M. P. , Revellino M. 
Published: April 2004

AbstractA model previously formulated or water sorption in polyester resin‐glass fiber composites has been applied to the kinetic analysis of experimental data for two composites containing a hydrolysable (polyvinyl acetate‐PVAc) and a non‐hydrolyzable (polystyrene‐PS) shrinkage‐controlling low‐profile additive (LPA) respectively. It was found that the equilibrium water uptake in the composites and their unreinforced matrix is not drastically affected by the type of LPA. The kinetics of water sorption in the composites, however, were substantially different. The PVAc composite displayed a two‐stage sorption process, the first stage being attributed to diffusion combined with hydrolysis, and the second to matrix swelling and plasticizing. A maximum in the kinetic curve was observed, and was due to changes in water solubility inside the matrix during sorption. In contrast, the PS composite displayed the typical kinetics of materials with slowly increasing hydrophilicity.
Compression molding of glass reinforced thermoplastics: Modeling and experiments
Authors: Dweib M. A. , Brádaigh C. M. Ó 
Published: April 2004

AbstractThe shearing and extensional behavior of glass mat‐thermoplastic (GMT) material under compression molding was investigated with a special model being developed for the case of non‐lubricated mold‐plate surfaces. Mathematical expressions for the radial and through‐thickness flow velocities were derived that enabled the derivation of extensional and shear strain rates. The GMT non‐lubricated (no‐slip wall conditions) compression molding was modeled as a combination of extensional and shearing flow and the two extensional and shear viscosities were determined. Scott's approach was used in this work to determine the radial velocit in the r‐direction, which depends on the shear power‐law expression. The velocity component in the z‐direction was then calculated using the continuity equation. The velocity profiles were used to calculate the shear and extensional strain rates. Scott's shear viscosity did not satisfy the constitutive equation for the extensional part, but a power‐law expression with new parameters depending on the deformation tensors was successfully used to calculate an independent extensional viscosity using the same non‐lubricated squeezing experiment. Lubricated squeezing flow was carried out for the same material to achieve a pure extensional flow, and the extensional viscosity calculated using this approach agreed with the extensional viscosity determined using the non‐lubricated experiment. GMT material used in this study is confirmed to have two layers of continuous long fibers orientated randomly inplane, separated by short chopped fibers in the middle, which suggests that the material can be treated as an isotropic material, and the fiber‐matrix separation is seen to be high at the extremities of the flow.