Showing papers on "Epoxy published in 2002"
TL;DR: In this article, a multi-walled carbon nanotube/epoxy resin composites have been fabricated by choosing an over-aged hardener, relatively soft and ductile matrix, a rubbery epoxy resin, has been obtained.
1,026 citations
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25 Nov 2002TL;DR: In this paper, the authors discuss the use of composite materials in the manufacturing process of a composite piece and the characteristics of the composite material properties, such as anisotropic properties and anisotropy and elasticity.
Abstract: PART ONE PRINCIPLES OF CONSTRUCTION COMPOSITE MATERIALS, INTEREST AND PROPERTIES What is Composite Material Fibers and Matrix What can be Made Using Composite Materials? Typical Examples of Interest on the Use of Composite Materials Examples on Replacing Conventional Solutions with Composites Principal Physical Properties FABRICATION PROCESSES Molding Processes Other Forming Processes Practical Hints in the Manufacturing Processes PLY PROPERTIES Isotropy and Anisotropy Characteristics of the Reinforcement-Matrix Mixture Unidirectional Ply Woven Fabrics Mats and Reinforced Matrices Multidimensional Fabrics Metal Matrix Composites Tests SANDWICH STRUCTURES: What is a Sandwich Structure? Simplified Flexure A Few Special Aspects Fabrication and Design Problems Nondestructive Quality Control CONCEPTION AND DESIGN Design of a Composite Piece The Laminate Failure of Laminates Sizing of Laminates JOINING AND ASSEMBLY Riveting and Bolting Bonding Inserts COMPOSITE MATERIALS AND AEROSPACE CONSTRUCTION Aircraft Helicopters Propeller Blades for Airplanes Turbine Blades in Composites Space Applications COMPOSITE MATERIALS FOR OTHER APPLICATIONS: Composite Materials and the Manufacturing of Automobiles Composites in Naval Construction Sports and Recreation Other Applications PART TWO: MECHANICAL BEHAVIOR OF LAMINATED MATERIALS ANISOTROPIC ELASTIC MEDIA: Review of Notations Orthotropic Materials Transversely Isotropic Materials ELASTIC CONSTANTS OF UNIDIRECTIONAL COMPOSITES: Longitudinal Modulus Poisson Coefficient Transverse Modulus Shear Modulus Thermoelastic Properties ELASTIC CONSTANTS OF A PLY ALONG AN ARBITRARY DIRECTION: Compliance Coefficients Stiffness Coefficients Case of Thermomechanical Loading MECHANICAL BEHAVIOR OF THIN LAMINATED PLATES: Laminate with Miplane Symmetry Laminate without Miplane Symmetry PART THREE: JUSTIFICATIONS, COMPOSITE BEAMS, THICK PLATES ELASTIC COEFFICIENTS Elastic Coefficients in an Orthotropic Material Elastic Coefficients for a Transversely Isotropic Material Case of a Ply THE HILL-TSAI FRACTURE CRITERION: Isotropic Material: Von Mises Criterion Orthotropic Material: Hill-Tsai Criterion Evaluation of the Resistance of a Unidirectional Ply with Respect to the Direction of Loading COMPOSITE BEAMS IN FLEXURE: Flexure of Symmetric Beams with Isotropic Phases The Case of any Cross Section (Asymmetric) COMPOSITE BEAMS IN TORSION: Uniform Torsion Location of the Torsion Center FLEXURE OF THICK COMPOSITE PLATES: Preliminary Remarks Displacement Field Strains Constitutive Relations Equilibrium Equations Technical Formulation for Bending Examples PART FOUR: APPLICATIONS LEVEL 1 Simply Supported Sandwich Beam Poisson Coefficient of a Unidirectional Layer Helicopter Blade Transmission Shaft for Trucks Flywheel in Carbon/Epoxy Wing Tip Made of Carbon/Epoxy Carbon Fibers Coated with Nickel Tube Made of Glass/Epoxy Under Pressure Filament Wound Reservoir, Winding Angle Filament Wound Reservoir, Taking into Account the Heads Determination of the Volume Fraction of Fibers by Pyrolysis Lever Arm Made of Carbon/Peek Unidirectionals and Short Fibers Telegraphic Mast in Glass/Resin Unidirectional Ply of HR Carbon Manipulator Arm of Space Shuttle LEVEL 2 Sandwich Beam: Simplified Calculations of the Shear Coefficient Procedure for Calculation of a Laminate Kevlar/Epoxy Laminates: Evolution of Stiffness Depending on the Direction of the Load Residual Thermal Stresses Due to Curing of the Laminate Thermoelastic Behavior of a Tube Made of Filament Wound Glass/Polyester Polymeric Tube Loaded by Thermal Load and Creep First Ply Fracture of a Laminate Ultimate Fracture Optimum Laminate for Isotropic Stress State Laminate Made of Identical Layers of Balanced Fabric Wing Spar in Carbon/Epoxy Determination of the Elastic Characteristics of a Carbon/Epoxy Unidirectional Layer from Tensile Test Sail Boat Shell in Glass/Polyester Determination of the in-Plane Shear Modulus of a Balanced Fabric Ply Quasi-Isotropic Laminate Orthotropic Plate in Pure Torsion Plate made by Resin Transfer Molding (RTM) Thermoelastic Behavior of a Balanced Fabric Ply LEVEL 3 Cylindrical Bonding Double Bonded Joint Composite Beam with Two Layers Buckling of a Sandwich Beam Shear Due to Bending in a Sandwich Beam Column Made of Stretched Polymer Cylindrical Bending of a Thick Orthotropic Plate under Uniform Loading Bending of a Sandwich Plate Bending Vibration of a Sandwich Beam Appendix 1: Stresses in the Plies of a Laminate of Carbon/Epoxy Loaded in its Plane Appendix 2: Buckling of Orthotropic Structures Bibliography
678 citations
TL;DR: In this paper, a self-healing polymeric composite material that can recover as much as 90 percent of its virgin fracture toughness has been developed, based on biological systems in which damage triggers an autonomic healing response.
Abstract: Inspired by biological systems in which damage triggers an autonomic healing response, a polymer composite material that can heal itself when cracked has been developed. In this paper we summarize the self-healing concept for polymeric composite materials and we investigate fracture mechanics issues consequential to the development and optimization of this new class of material. The self-healing material under investigation is an epoxy matrix composite, which incorporates a microencapsulated healing agent that is released upon crack intrusion. Polymerization of the healing agent is triggered by contact with an embedded catalyst. The effects of size and concentration of the catalyst and microcapsules on fracture toughness and healing efficiency are investigated. In all cases, the addition of microcapsules significantly toughens the neat epoxy. Once healed, the self-healing polymer exhibits the ability to recover as much as 90 percent of its virgin fracture toughness.
549 citations
TL;DR: In this article, the authors investigated the possibility of improving the mechanical properties of high-functionality epoxy resins through dispersion of octadecyl ammonium ion-modified layered silicates within the polymer matrix.
417 citations
TL;DR: In this article, liquid amine-terminated butadiene acrylonitrile (ATBN) copolymers were added at different contents to improve the toughness of diglycidyl ether of bisphenol A epoxy resins using polyaminoimidazoline as a curing agent.
382 citations
TL;DR: In this article, a comparative study of the sized fiber surface topography and modulus as well as the local mechanical property variation in the interphase of E-glass fibre reinforced epoxy resin and Eglass fiber reinforced modified polypropylene (PPm) matrix composites was conducted.
Abstract: The local microstructure can be altered significantly by various fibre surface modifications, causing property differences between the interphase region and the bulk matrix. By using tapping mode phase imaging and nanoindentation tests based on the atomic force microscope (AFM), a comparative study of the sized fibre surface topography and modulus as well as the local mechanical property variation in the interphase of E-glass fibre reinforced epoxy resin and E-glass fibre reinforced modified polypropylene (PPm) matrix composites was conducted. The phase imaging AFM was found a highly useful tool for probing the interphase with much detailed information. Nanoindentation experiments indicated the chemical interaction during processing caused by a gradient profile in the modulus across the interphase region of γ-aminopropyltriethoxy silane (γ-APS) and polyurethane (PU)-sized glass fibre reinforced epoxy composite. The interphase with γ-APS/PU sizing is much softer than the PPm matrix, while the interphase with the γ-APS/PP sizing is apparently harder than the matrix, in which the modulus was constant and independent of distance away from the fibre surface. The interphase thickness varied between less than 100 and ≈300 nm depending on the type of sizing and matrix materials. Based on a careful analysis of ‘boundary effect’, nanoindentation with sufficient small indentation force was found to enable measuring of actual interphase properties within 100 nm region close to the fibre surface. Special emphasis is placed on the effects of interphase modulus on mechanical properties and fracture behaviour. The interphase with higher modulus and transcrystalline microstructure provided simultaneous increase in the tensile strength and the impact toughness of the composites.
325 citations
TL;DR: In this article, a methodology has been developed for construction of atomistic models of crosslinked polymer networks, applied to low molecular weight water soluble epoxy resins crosslinked with different curing agents that are being considered for use as a primer coating on steel.
323 citations
TL;DR: In this article, the characterization of composite material suitable for constructing structural parts devoted to dissipate kinetic energy during impacts is discussed. But the impact behavior of the material is not investigated.
313 citations
TL;DR: In this paper, the degradation of an IM7/997 carbon fiber-reinforced epoxy exposed to ultraviolet radiation and/or condensation has been characterized based on observations of physical and chemical degradation, and it has been established that these environments operate in a synergistic manner that causes extensive erosion of the epoxy matrix, resulting in a reduction in mechanical properties.
Abstract: The degradation of an IM7/997 carbon fiber-reinforced epoxy exposed to ultraviolet radiation and/or condensation has been characterized. Based on observations of physical and chemical degradation it has been established that these environments operate in a synergistic manner that causes extensive erosion of the epoxy matrix, resulting in a reduction in mechanical properties. Matrix dominated properties are affected the most, with the transverse tensile strength decreasing by 29% after only 1000 h of cyclic exposure to UV radiation and condensation. While, the longitudinal fiber-dominated properties are not affected for the exposure durations investigated, it has been noted that extensive matrix erosion would ultimately limit effective load transfer to the reinforcing fibers and lead to the deterioration of mechanical properties even along the fiber dominated material direction.
282 citations
TL;DR: In this paper, multiwalled carbon nanotubes (MWNT) reinforced epoxy composite thin films were prepared by a microfabrication process and their elastic modulus was determined using a shaft-loaded blister test and linear and nonlinear elasticity models.
Abstract: Multiwalled carbon nanotubes (MWNT) reinforced epoxy composite thin films were prepared by a microfabrication process and their elastic modulus was determined using a shaft-loaded blister test and linear and nonlinear elasticity models. Compared to net resin thin films, a 20% increase in elastic modulus was seen when 0.1 wt % MWNTs were added, suggesting MWNT alignment by spin coating. Electron microscopic observations of the fracture surfaces suggested high interfacial shear stress between MWNTs and the epoxy matrix, a result supported by both molecular mechanics simulation and micromechanics calculations.
279 citations
TL;DR: In this article, the curing kinetics of diglycidyl ether of bisphenol A (DGEBA) and DGEHQ epoxy resins in the presence of TETA as a reactive diluent and triethylenetetetramine (TETA) as the curing agent were studied by non-isothermal differential scanning calorimetry (DSC) technique at different heating rates.
TL;DR: In Part A of the World Wide Failure Exercise (published in Composite Science and Technology, Vol 58, No 7, 1998), all contributors were given exactly the same set of material properties and were asked to predict the strength and deformation of a set of laminates under a range of specified loading conditions as discussed by the authors.
TL;DR: In this article, various amounts of micro and nano-scale particles (titanium dioxide TiO 2, 200-400 nm, calcium silicate CaSiO 3, 4-15 μm) were introduced into an epoxy polymer matrix for its reinforcement.
Abstract: It is well known that inorganic filler particles enhance the mechanical and tribological properties of polymers. The stiffness, toughness, and wear performance of the composites are extensively determined by the size, shape, volume content, and especially the dispersion homogeneity of the particles. In the present study, various amounts of micro- and nano-scale particles (titanium dioxide TiO 2 , 200-400 nm, calcium silicate CaSiO 3 , 4-15 μm) were introduced into an epoxy polymer matrix for its reinforcement. The influence of these particles on the impact strength, dynamic mechanical thermal properties, and block-on-ring wear behavior was investigated. Using only the nano-particles, the results demonstrate the best improvement in stiffness, impact strength, and wear resistance of the epoxy at a nano-particle content of 4 vol% TiO 2 . Therefore, this nanocomposite was used to act as a matrix for the CaSiO 3 micro-particles, in the hope of finding synergistic effects between the micro- and the nano-particles. Results show, in fact, a further improvement of wear resistance and stiffness, whereas the impact strength suffers. Geometrical properties of the particles, the homogeneous dispersion state, energy dissipating fracture mechanisms, and a transition of wear mechanisms mostly contribute to the increase in performance.
TL;DR: In this article, an irradiation grafting method was applied to modify nanosilica by covalently bonding polyacrylamide (PAAM) onto the particles.
TL;DR: In this article, a silicon-containing epoxy compound was obtained by reacting a bisphenol-A type epoxy and an o -cresol-formaldehyde novolac type epoxide with diphenyl-silandiol and triphenylsilanol, respectively.
TL;DR: In this article, the epoxy−amine reaction was investigated using different techniques: dynamic mechanical thermal analysis (DMTA), transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS).
Abstract: Epoxy thermoset blended with polystyrene-block-polybutadiene-block-poly(methyl methacrylate) triblock copolymers have been investigated before and after the epoxy−amine reaction, coupling different techniques: dynamic mechanical thermal analysis (DMTA), transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). Before reaction, the three blocks self-organize on a nanometer scale, in PS spheres surrounded by PB nodules while the PMMA blocks are solubilized with the epoxy precursors, forming a swollen corona. Using MCDEA as hardener, the domain sizes were found not to be affected throughout the network formation. The final structure is composed of undiluted PS and PB blocks forming a “spheres on spheres” morphology, most of the PMMA chain remaining embedded in the epoxy network. A partial deswelling of the PMMA brush does occur during the epoxy−amine reaction, resulting in a pure PMMA phase. This phase, evidenced by DMTA, is most likely located at the vicinity of the interface with the...
TL;DR: The tension-tension fatigue behavior of different natural fiber reinforced plastics was investigated in this paper, where composites used were made of flax and jute yarns and wovens as reinforcements for epoxy resins, polyester resins and polypropylene.
Abstract: The tension–tension fatigue behaviour of different natural fibre reinforced plastics was investigated. The composites used were made of flax and jute yarns and wovens as reinforcements for epoxy resins, polyester resins and polypropylene. Fibre type, textile architecture, interphase properties, fibre properties and content were found to affect the fatigue behaviour strongly as illustrated with damping versus applied maximum load curves. It was found that natural fibre reinforced plastics with higher fibre strength and modulus, stronger fibre–matrix adhesion or higher fibre fractions possess higher critical loads for damage initiation and higher failure loads. In addition, damage propagation rates were reduced. Furthermore, unidirectional composites were less sensitive to fatigue induced damage than woven reinforced ones.
TL;DR: In this article, two relaxation processes are revealed in the frequency range and temperature interval of the measurements, one is an interfacial dielectric relaxation (Maxwell-Wagner-Sillars), MWS and the other is a conductivity relaxation.
Abstract: Composites of epoxy resins and nickel particles in various amounts were prepared and their dielectric spectra were measured in the frequency range 5 Hz–13 MHz and temperature interval from ambient to 140°C. The formalism of electric modulus proved to be efficient in analysing and interpreting obtained data. For these composites two relaxation processes are revealed in the frequency range and temperature interval of the measurements. One is an interfacial dielectric relaxation (Maxwell–Wagner–Sillars), MWS and the other is a conductivity relaxation. They both follow the Cole–Davidson approach with the exponent γ reflecting a distribution of relaxation times with the characteristics of each process. AC conductivity of these composites is frequency and temperature dependant, it generally follows the exponential law σ ac ∼ ω s and reveals a conductivity relaxation process, in the low frequencies.
TL;DR: In this paper, longitudinal stiffeners were used in composite materials for use in composite composite materials, where plant fibers are of increasing interest for composite materials and waste management is easier than with glass fibers.
Abstract: Plant fibers are of increasing interest for use in composite materials. They are renewable resources and waste management is easier than with glass fibers. In the present study, longitudinal stiffn ...
TL;DR: In this paper, an unprecedented high thermal conductivity of 695 W/m K for polymer matrix composites was obtained, and the densities of all the composites are lower than 1.5 g/cc.
TL;DR: In this article, the effects of particle reinforcement, both micro and nano scale, on the response of carbon fiber/epoxy composites to cryogenic cycling were studied. But the mechanical properties of the laminates studied were not significantly altered through nanoclay modification of the matrix.
TL;DR: In this paper, the exfoliation mechanism and thermal-mechanical properties of surface-initiated epoxy nanocomposites were studied, and it was found that differences in the activation energies of interlayer expansion and of curing influence the final nanostructures of the materials.
TL;DR: In this paper, a small-diameter fiber Bragg grating (FBG) sensor was used for the detection of the delamination in carbon fiber reinforced plastic (CFRP) cross-ply laminates.
Abstract: Newly developed small-diameter fiber Bragg grating (FBG) sensors were applied for the detection of the delamination in carbon fiber reinforced plastic (CFRP) cross-ply laminates Since the diameter of the FBG sensor was very small, the sensor was easily embedded into the 0° ply along the reinforcing carbon fibers The reflection spectra from the FBG sensor were measured at various delamination lengths through four-point bending test The form of the spectrum changed sensitively, as the delamination length increased Moreover, the spectrum was calculated theoretically for confirmation of the measured spectrum The calculated result reproduced the change in the measured spectrum very well Then, we proposed the intensity ratio in the spectrum as an effective indicator for the prediction of the delamination length This indicator has a potential to be applied to other laminate configurations
TL;DR: In this paper, the surface properties of a high modulus unsized carbon fiber modified by aqueous ammonia were studied and basic groups were detected by potentiometric titration in addition to the pristine acid groups in untreated fiber.
01 Aug 2002
TL;DR: It was found that chemical treatment with phosphoric acid solution significantly affected the degree of adhesion at interfaces between fibers and resin matrix, resulting in improved mechanical interfacial strength in the composites.
Abstract: In this work, the effects of chemical treatment on Kevlar 29 fibers have been studied in a composite system. The surface characteristics of Kevlar 29 fibers were characterized by pH, acid–base value, X-ray photoelectron spectroscopy (XPS), and FT-IR. The mechanical interfacial properties of the final composites were studied by interlaminar shear strength (ILSS), critical stress intensity factor ( K IC ), and specific fracture energy ( G IC ). Also, impact properties of the composites were investigated in the context of differentiating between initiation and propagation energies and ductile index (DI) along with maximum force and total energy. As a result, it was found that chemical treatment with phosphoric acid solution significantly affected the degree of adhesion at interfaces between fibers and resin matrix, resulting in improved mechanical interfacial strength in the composites. This was probably due to the presence of chemical polar groups on Kevlar surfaces, leading to an increment of interfacial binding force between fibers and matrix in a composite system.
TL;DR: In this paper, the effect of carbon black (CB) concentration on the network structure of epoxy composites, such as volume fraction of the epoxy network (V r ), the extent of CB reinforcing, interparticle distance between conductive particles (IPD), epoxy solvent interaction parameter ( χ), average number molecular weight between cross-links (M c ), number of elastically effective chains (NEC), cross-linking density (CLD), and scanning electron microscope (SEM) was investigated in details.
TL;DR: In this article, a two component room temperature curing adhesive paste (Araldite 2014) has been selected and the characterization of the adhesive properties was conducted with respect to the curing temperature and to the elapsed time between the gluing and the testing.
TL;DR: In this article, the mechanical properties of nylon 6 and its blends with maleated ethylene-propylene rubber (EPR-g-MA) plus glass fibers were examined as a function of the chemical functionality of the silane surface treatment applied to the glass fibers.
TL;DR: In this article, a new diepoxide and a new diamine, both bearing bis-(9,10-dihydro-9-oxa-10-oxide-10phosphaphenanthrene-10yl-)-substituted methylene linkages, were prepared through the reaction of 9,10dihdro-ox a 10-phosphamide-10oxide with benzophenone derivatives via a simple addition reaction followed by a dehydration reaction.
Abstract: A new diepoxide and a new diamine, both bearing bis-(9,10-dihydro-9-oxa-10-oxide-10-phosphaphenanthrene-10-yl-)-substituted methylene linkages, were prepared through the reaction of 9,10-dihydro-oxa-10-phosphaphenanthrene-10-oxide with benzophenone derivatives via a simple addition reaction followed by a dehydration reaction. These two compounds were used as monomers for preparing cured epoxy resins with high phosphorus contents. The resultant epoxy resins showed high glass-transition temperatures (between 131 and 196 °C). All of the cured epoxy resins exhibited high thermal stability, with 5% weight loss temperatures over 316 °C, and excellent flame retardancy, with limited oxygen index values of 37-50.