Showing papers in "Composite Interfaces in 1994"
TL;DR: The applicability of the microbond test to evaluate the interfacial properties between cellulosic fibers and thermoplastics was studied in this article, where the apparent diameters and surface free energies of the fibers were estimated by dynamic contact angle (DCA) analysis.
Abstract: The applicability of the microbond test to evaluate the interfacial properties between cellulosic fibers and thermoplastics was studied. Acetylation and heat treatment were applied to modify the surface of cellulosic fibers (rayon, cotton, and wood). The apparent diameters and surface free energies of the fibers were estimated by dynamic contact angle (DCA) analysis. Interfacial shear strengths between the cellulosic fibers and the polystyrene matrix were determined using the microbond test method. The test results indicate that acetylation increases the total surface free energy of the wood fibers, whereas heat treatment dramatically decreases the surface free energy of all cellulosic fibers tested. For heat treated and acetylated fibers, the greater the surface free energy, the greater the interfacial shear strength (ISS) regardless of fiber types. For control group fibers, a low ISS exists even though the fibers have high surface free energies because of the formation of a weak boundary layer. The high...
79 citations
TL;DR: In this paper, the authors present a review of the technology of toughening composites by fiber coating, showing the composite systems, coating materials, fiber coating methods and toughness mechanisms which have been studied.
Abstract: Continuous fiber, high-performance composites have found increased use in the design of a large number of civilian and military aircraft. However, the brittle nature of the carbon fiber and the resins used as matrices have restricted the full utilization of these materials in aerospace application. Hence, the development of toughened composites has a great potential for expanding the use of current materials, and a major effort is being undertaken in order to develop toughened composites. Due to several advantages of introducing a ductile or flexible material between the fiber and matrix, coating the fiber with polymers has recently received considerable interest and much effort has been done to understand the effect of the interlayer on composite properties. This paper reviews the technology of toughening composites by fiber coating, showing the composite systems, coating materials, fiber coating methods and toughness mechanisms which have been studied. Finally, a separate section is dedicated to reviewi...
59 citations
TL;DR: In this paper, the micro-mechanical behavior of fiber/matrix interfaces and macroscopic mechanical properties of glass fiber reinforced Nylon 6 composites have been characterized using in situ microscopic observation techniques.
Abstract: The micro-mechanical behavior of fiber/matrix interfaces and macroscopic mechanical properties of glass fiber reinforced Nylon 6 composites have been characterized for four different fiber surface treatments using in situ microscopic observation techniques. A pull-out test under an optical microscope is conducted to determine the interfacial bond strength of single-fiber embedded composites. An elasto-plastic axisymmetric finite element analysis is then used to explain the experimentally-obtained different failure mechanisms and processes at a broken fiber end. In addition, micro-deformation and failure process in injection-molded composites are observed under tensile loading in a scanning electron microscope (SEM) for specimens reinforced with randomly-oriented short glass fibers with the same fiber surface treatments. It is revealed that micro-damage and fracture characteristics in injection-molded thermoplastic composites are well correlated with micro-mechanical properties of fiber/matrix interfaces o...
27 citations
TL;DR: In this article, the effects of testing temperature and the fibre/matrix adhesion on the crushing performances of composite tubes were identified. But the main objective of this work was not to identify the effect of test temperature on composite tube performance.
Abstract: The primary objective of this work is to identify the effects of testing temperature and the fibre/matrix adhesion on the crushing performances of composite tubes. Axial compressive tests were carried out on glass cloth/epoxy resin composite tubes at different temperatures ranging from - 140°C to 150°C. Two kinds of composite tube were investigated; the first tubes were reinforced with glass cloth treated with amino-functional silane coupling agent, and the others were reinforced with glass cloth treated with acrylsilane coupling agent. The crushing performances of aminosilane-treated tubes were higher than those of acrylsilane-treated tubes. The crushing performances of both kinds of tube decreased with increasing testing temperature. Room temperature tests produced crush zones of the splaying mode in aminosilane-treated tubes and fragmentation mode in acrylsilane-treated tubes. At low temperatures both the aminosilane-treated and acrylsilane-treated tubes were crushed by splaying mode. At high temperatu...
23 citations
TL;DR: In this paper, the surface carboxyl groups are able to bind poly(methyl methacrylate) chains (Mn, 1700) of 0.86-1.29 mg/g by condensation reactions.
Abstract: Polymer modification of monodispersed colloidal silica (0.5 μm) and introduction of carboxyl groups on the surface are studied. The reactions of surface silanol with alternate copolymer silane coupling agents, prepared by maleic anhydride and styrene, methyl methacrylate or vinyl acetate, are effectively promoted by azeotropic removal of ethanol and water from the reaction system. Cross-linking of bound polymer on silica particles by esterification with diol results in simultaneous formation of carboxyl group of 0.15-0.21 mmol/g. The surface carboxyl groups are able to bind poly(methyl methacrylate) chains (Mn, 1700) of 0.86-1.29 mg/g by condensation reactions.
20 citations
TL;DR: In this paper, the effect of parameters such as wettability, mechanical interlocking due to diffusion, and specific interactions on adhesion of glass-fiber reinforced composite materials is considered.
Abstract: The performance of glass-fiber reinforced composite materials is strongly dependent on adhesion at the fiber-matrix interface. This study has considered the effect of parameters such as wettability, mechanical interlocking due to diffusion, and specific interactions on adhesion. The surface characteristics of treated and untreated glass fibers were studied by inverse gas chromatography. Donor/acceptor concepts were used to calculate a specific (acid/base) interaction parameter for fiber/matrix pairs. Tensile strengths of composites with Nylon-6,6 and polyethylene correlated with both acid-base and dispersive interactions. Initial attempts were made to separate and quantify contributions to interfacial bonding from dispersive forces, acid/base forces, diffusion and the mechanical interlocking of constituents. Findings were supported by scanning electron microscopy of the fracture surfaces of composite samples.
19 citations
TL;DR: In this paper, the authors present results for a simulation of adhesive failure at a model metal/oxide heterophase interface between an aluminum (111) face and an α-alumina (0001) face.
Abstract: We report on the development of a novel computational method for molecular dynamics simulations which explicitly includes variable charge transfer between anions and cations. This method is found to be capable of describing the elastic properties, surface energies, and surface relaxation of crystalline metal-oxides accurately. We present results for a simulation of adhesive failure at a model metal/oxide heterophase interface between an aluminum (111) face and an α-alumina (0001) face. Our results indicate that this approach can provide physically realistic empirical potentials for future simulations on mixed metal/metal-oxide systems.
14 citations
TL;DR: In this article, a study was done to increase the understanding of the mechanism responsible for fiber/matrix interaction in carbon fiber/thermoplastic composite, which suggested that the formation of the fiber/ matrix interaction was primarily related to a chemisorption mechanism.
Abstract: This work was undertaken in order to increase the understanding of the mechanism responsible for fiber/matrix interaction in carbon fiber/thermoplastic composite From results of previous study on carbon fiber/PEEK composite, which suggested that the formation of the fiber/ matrix interaction was primarily related to a chemisorption mechanism, a study was done of the conditions required to obtain efficient fiber/matrix interaction in PA-12 and PP/carbon fiber composites The interest in studying carbon fiber composite based on PP and PA-12 was that these two matrices are very different in terms of reactivity, polyamide having many more reactive groups than polypropylene As expected, due to the non-reactive chemical structure of the polypropylene, fiber/matrix interaction in carbon fiber/PP composite occurred only when the matrix was thermally degraded, ie when the composite was molded at high temperature or under long residence time at the melt temperature For the carbon fiber/PA-12 composite, strong
14 citations
TL;DR: In this paper, a series of n-alkanes with the surface of highly ordered pyrolytic graphite (HOPG) using scanning tunneling microscopy (STM) and molecular dynamics (MD) computer simulation was investigated.
Abstract: _We have conducted an investigation of the interaction of a series of n-alkanes with the surface of highly ordered pyrolytic graphite (HOPG) using scanning tunneling microscopy (STM) and molecular dynamics (MD) computer simulation. The alkanes studied in this work (CnH2n+2 with n=16, 17, 20, 28, and 32) yield STM images which are highly suggestive of an ordered quasi-two-dimensional phase on the graphite surface. Individual molecules on the graphite surface adopt a rod-like conformation and are arranged in a 'rank-and-file' structure. Analysis of the STM height profiles indicates the presence of two dominant spatial frequency components. The high-frequency component has a period of about 0.30 nm and is independent of the carbon number of the alkane. The low frequency components have periods ranging from 3 nm to 5.5 nm. These values correlate closely with those obtained from estimates of the length of fully extended alkanes and from molecular dynamics computer simulations of surface-adsorbed alkanes. These...
13 citations
TL;DR: By monitoring the peak position of strain sensitive Raman bands, Raman spectroscopy can be used to study the distribution of stress or strain along discontinuous aramid fibres fully embedded in an epoxy resin matrix from which the interfacial shear stress can be calculated as mentioned in this paper.
Abstract: By monitoring the peak position of strain-sensitive Raman bands, Raman spectroscopy can be used to study the distribution of stress or strain along discontinuous aramid fibres fully embedded in an epoxy resin matrix from which the interfacial shear stress can be calculated The technique has been used to study the effect of fibre tensile properties and applied surface treatments upon the efficiency of stress transfer from the matrix to the fibre At low levels of matrix strain the distribution of stress or strain along the fibre can be defined using classical shear lag theory from which the effect of fibre modulus can be distinguished Values of interfacial shear stress were found to be higher for those fibres pretreated with an epoxy solution This may be attributed to changes in the matrix properties in the vicinity of the fibre/matrix region In the case of the untreated fibre samples interfacial failure was initiated by yielding of the fibre/matrix interface followed by debonding at the fibre ends Th
12 citations
TL;DR: In this paper, the formation of macromolecular aggregates in dilute and semidilute solutions of the blend of two thermodynamically miscible polymers, polycarbonate and poly- Σ -caprolactone was studied.
Abstract: The formation of macromolecular aggregates in dilute and semidilute solutions of the blend of two thermodynamically miscible polymers, polycarbonate and poly- Σ -caprolactone was studied. It was found that the critical concentration of crossover in solutions of blends depends on the ratio of components. Adsorption on aerosil from solutions of blends in dilute and semidilute regimens has been investigated and is characterized by the appearance of the maxima on isotherms at concentrations near the critical concentration of crossover. Increasing concentration of the solution leads to a reduction of the fraction of bound segments. The thickness of the adsorbed layer was estimated at various concentrations, assuming that all the surface of the sorbent is saturated at low solution concentration and that the increase of adsorption associated with the increase in concentration is associated with the adsorption of aggregates and the rearrangement of the structure of adsorption layer.
TL;DR: In this paper, a fracture model of multi-fiber composites in which shear-lag-analysis, fracture mechanics and a Monte Carlo simulation method were incorporated was applied to describe the fracture process and strength of composites.
Abstract: A mesomechanical modeling approach was applied to estimate the influences of interfacial chemical reaction and interfacial bonding strength on tensile behavior and strength of fiber-reinforced metal matrix composites. First, a fracture mechanical model of single fiber coated with thin brittle surface layer was applied to describe strength of fiber on which interfacial reaction layer or artificial coating layer exists. With this model, influences of interfacial bonding strength between fiber and surface layer, difference in mechanical properties between fiber and surface layer, thickness of surface layer and discontinuity of surface layer on fiber strength were clarified. Second, a fracture model of multi-fiber composites in which shear-lag-analysis, fracture mechanics and a Monte Carlo simulation method were incorporated was applied to describe the fracture process and strength of composites. With this method, the influences of interfacial bonding strength between fiber and matrix in association with scat...
TL;DR: In this article, the thermal residual stress induced in the fiber during specimen preparation, prior to a single-fiber fragmentation experiment, is studied using various theoretical schemes, and it is found that the longitudinal component of this stress is compressive in nature, and that in some cases it is high enough to induce breaks in fiber.
Abstract: The thermal residual stress induced in the fiber during specimen preparation, prior to a single-fiber fragmentation experiment, is studied using various theoretical schemes. It is found that the longitudinal component of this stress is compressive in nature, and that in some cases it is high enough to induce breaks in the fiber. The number of such pre-existing breaks may be calculated under certain conditions, one of them being that the Weibull shape parameter of the fiber compressive strength distribution be known. Experimental data produced with high-modulus graphite/polypropylene single-fiber composites are used to substantiate the arguments presented. Implications for high fiber content composites are discussed.
TL;DR: In this paper, existing data on contact angles are reviewed and analysed in order to answer the following three questions related with the modelling of reactive wetting: (1) Does a relation between wettability, which is a 2D phenomenon, and bulk reactivity really exist? (2) If so, what are the mechanisms by which an interfacial reaction can modify wetability? (3) What are the criteria for selection of alloying elements able to act as wetting agents? From the answers to these questions, a new description of the relationship between reactivity,
Abstract: Non-reactive pure metals do not wet ionocovalent oxides like alumina and silica. It is believed generally that a strong improvement of wetting can be produced by alloying elements presenting a high reactivity with the oxide substrate. In this study, existing data on contact angles are reviewed and analysed in order to answer the following three questions related with the modelling of reactive wetting: (1) Does a relation between wettability, which is a 2D phenomenon, and bulk reactivity (3D) really exist? (2) If so, what are the mechanisms by which an interfacial reaction can modify wettability? (3) What are the criteria for selection of alloying elements able to act as wetting agents? From the answers to these questions, a new description of the relationship between reactivity, wettability and adhesion in metal/oxide systems is given.
TL;DR: In this paper, a model of finite element analysis was proposed to calculate mechanical properties of single ply of woven fabric composites considering interfacial properties, where microfracture in the fiber bundle was regarded as interfacial fracture.
Abstract: A model of finite element analysis was proposed to calculate mechanical properties of single ply of woven fabric composites considering interfacial properties. In this model, microfracture in the fiber bundle was regarded as interfacial fracture. Woven fabric structure was modeled using a pair of parallel beam elements expressing a fiber bundle and an interphase element between the two elements. Stress of the composite was calculated at the fracture of each element under tensile load, and the fracture process was simulated. The first fracture occurred in the interphase along the transverse bundle. Secondly, resin at the surface of the composite was seen to fail as did the longitudinal fiber. The stress of the composite at the interphase fracture was calculated with various properties of the interphase. The calculation showed that the lower modulus and higher strength interphase has high resistance to the microfracture. Another calculation was carried out with different weaving densities to evaluate the ef...
TL;DR: In this paper, the effect of impregnation techniques on bending properties of glass fiber reinforced polyethylene terephthalate (PET) composites was investigated using both commingled yarn and parallel yarn methods.
Abstract: An investigation was conducted to check the effect of impregnation techniques on bending properties of glass fiber reinforced polyethylene terephthalate (PET). The impregnation techniques used commingled yarn and parallel yarn methods. Holding time during fabrication varied between 1 and 20 min. The morphology and thermal properties of the composites were studied by using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The results showed that commingled yarn can be fabricated at low pressure with good impregnation characteristics whilst parallel yarn requires a high pressure before a good impregnation of matrix resin into fiber can be achieved. Bending properties of commingled yarn composites were higher than those of parallel yarn composites. This was due to different impregnation techniques. The crystallinity of the matrix resin was not affected by different holding time during compression molding.
TL;DR: In this paper, the interface microstructure between α-silicon nitride whiskers and the 6061 aluminum matrix in a squeeze cast composite was observed by transmission electron microscopy.
Abstract: The interface microstructure between α-silicon nitride whiskers and the 6061 aluminum matrix in a squeeze cast composite was observed by transmission electron microscopy. No reaction product was found at the interface. Only a strain field in the matrix near the interface was observed. The strain field induced a thin layer along the interface in which the aluminum lattice was distorted. This layer occasionally looked like an amorphous layer when observed under the exact Bragg diffraction condition of the matrix, but it seemed not to be really amorphous. After prolonged reaction at 800°C, the whiskers reacted with the matrix to produce aluminum nitride and silicon.
TL;DR: Fractal analysis of surfaces of several commercial and experimental reinforcing fibers is reported in this paper, showing that the fractal nature of the fiber surfaces implies that the interphase regions also have fractal morphology.
Abstract: Fractal analysis of surfaces of several commercial and experimental reinforcing fibers is reported. Atomic force microscope images of fiber surfaces demonstrate the self-affinity of surface topography over a range of scales. The roughness of the fiber surfaces was calculated after the cylindrical curvature was removed by subtracting a fitted second order polynomial. Fractal dimensions of surfaces were evaluated. The fractal dimension of graphite T40R fiber was 2.09. The fractal dimension of Kevlar® 149 fiber was 2.37. Fractal dimensions of high temperature polyimide BPDA-PFMB fibers decreased from 2.52 for as spun, undrawn fibers to 2.18 for a fiber with a draw ratio 8. The fractal nature of the fiber surfaces implies that the interphase regions also have fractal morphology. Study of the nature of a fractal interface is expected to lead to new insight into the transfer of stress between the fiber and the matrix.
TL;DR: In this article, pull-out experiments have been carried out with Kevlar fibres embedded in epoxy resin, and the debonding stress was about equal to the matrix strength for 80°C cured epoxies.
Abstract: Pull-out experiments have been carried out with Kevlar fibres embedded in epoxy resin. Friction accompanied debonding, and had to be allowed for in the analysis. The debonding stress was about equal to the matrix strength for 80°C cured epoxies. However, debonding appears to be a brittle fracture process, and the works of fracture corresponding to the apparent interface strengths are very low, ranging from ca. 20-40 Jm-2 depending on the surface treatment and degree of cure of the resin. Water immersion for 2300 h at room temperature reduced the apparent strengths and works of fracture with some of the surface treated fibres, but not with the untreated fibres. Interface pressures during debonding were 10-15 MPa for the 20°C cured specimens and 20-30 MPa for the 80°C cure. Water soaking markedly reduced the friction coefficients. Post-debonding friction was high, but estimates of the parameters was probably unreliable due to the fibre having a somewhat thick end due to fibrillation when being cut.
TL;DR: In this article, the effect of a variety of solvents on adhesion between polyethylene moldings and molten polyethylenes has been investigated, and the adhesive strength between the molten polyelenes and the polyethyline moldings has been shown to be stable in the range of 250 to 300°C.
Abstract: The effect of a variety of solvents on adhesion between polyethylene moldings and molten polyethylenes has been investigated. The adhesive strengths between the molten polyethylenes heated in the range of 250 to 300°C and the polyethylene moldings, on which organic solvents, such as xylene, decalin, tetralin and o-dichlorobenzene were precoated, sharply increased, and indicated stable high values. This effect was evident for such molten polyethylenes as LDPE, HDPE and HMWPE. This results from the local dissolution of the polyethylene surface and molten polyethylenes, and subsequent recrystallization of polyethylene molecules in both the surface of the molten polyethylene and polyethylene moldings as the solvents evaporate.
TL;DR: In this article, a comparative study of interfacial effects due to styrene-butadiene-based triblock copolymer (SEBS) addition and to corona treatment has been investigated for blends of polyethylene (PE) and polystyrene (PS).
Abstract: A comparative study of interfacial effects due to styrene-butadiene-based triblock copolymer (SEBS) addition and to corona treatment has been investigated for blends of polyethylene (PE) and polystyrene (PS). Blends of PS/PE covering a wide range of weight composition have been prepared in the molten state. Scanning electron microscopy demonstrated that moderate amounts of SEBS copolymer addition (2-5%) resulted in finer particle dispersion and in better interfacial adhesion between PE and PS phases. Tensile strength and elongation at break were also significantly improved. In the case of corona treatment of both polyethylene and polystyrene, the tensile strength of the blends increased while their elongation at break remained almost unchanged. The same trend was found when small amounts of corona-treated blend (5%) were added to the non-modified PS/PE blends. Rheological measurements revealed that corona treatment resulted in a decrease of dynamic shear viscosity of both PE and PS. From a view-point of m...
TL;DR: In this article, a method for the determination of moisture penetration depth at the fiber/matrix interface in graphite fiber polymer matrix composites as a function of time and degree of polarization was proposed.
Abstract: In certain engineering applications, graphite fiber polymer matrix composites may be exposed to both moisture and electrochemical polarization. The combined effect to these environmental conditions can cause fiber/matrix interfacial breakdown and matrix degradation. In previous research, electrochemical impedance spectroscopy (EIS) was used to examine the effects of electrochemical polarization on bismaleimide (BMI)/graphite fiber (GF) composites, and revealed changes in the impedance spectra that suggested porous behavior. This 'porosity' was attributed to moisture ingress at the fiber/matrix interface. At present, no techniques are available to determine the depth of moisture penetration in these materials in a nondestructive manner. This paper introduces a new method for the determination of moisture penetration depth at the fiber/matrix interface in graphite fiber polymer matrix composites as a function of time and degree of polarization. The method is a nondestructive, in situ technique which has the...
TL;DR: In this paper, the surface of aluminum plates were modified by coating with a thin layer of copper and subsequently reacting with 2-mercaptobenzimidazole (MBIH) or benzotriazole(BTAH) Chemisorption of an epoxy compound on top of adsorbed MBIH and BTAH on copper metal has been investigated by the use of surface enhanced Raman scattering (SERS) aluminum-polymer laminated composites were prepared by sandwiching aluminum plates and the epoxy resin reinforced with carbon fabrics.
Abstract: The surface of aluminum plates were modified by coating with a thin layer of copper and subsequently reacting with 2-mercaptobenzimidazole (MBIH) or benzotriazole (BTAH) Chemisorption of an epoxy compound on top of adsorbed MBIH and BTAH on copper metal has been investigated by the use of surface enhanced Raman scattering (SERS) Aluminum-polymer laminated composites were prepared by sandwiching aluminum plates and the epoxy resin reinforced with carbon fabrics Experimental data show that the laminated composites composed of the Cu-MBIH modified aluminum plates exhibit a higher strength and better water-resistance
TL;DR: In this paper, the acylium perchlorate groups were successfully introduced onto the surface of a carbon whisker, i.e. a vapor-grown carbon fiber, by the reaction of acyl chloride groups on the surface with silver perchlorates in nitrobenzene at room temperature.
Abstract: The acylium perchlorate groups were successfully introduced onto the surface of a carbon whisker, i.e. a vapor-grown carbon fiber, by the reaction of acyl chloride groups on the surface with silver perchlorate in nitrobenzene at room temperature. The cationic ring-opening polymerizations of 1,3,5-trioxane and 1,3-dioxolane were initiated by the acylium perchlorate groups on the surface and the corresponding polyacetals were grafted onto carbon whisker: the percentage of poly(oxymethylene) grafting increased to 60%. The initiating activity increased with an increase in acylium perchlorate group content. Although the grafted poly(oxymethylene) on the surface was subject to stepwise thermal depolymerization from the chain end, the thermal stability was improved by acetylation of the end group. In addition, the acylium perchlorate groups on the surface have an ability to initiate the cationic copolymerization of 1,3,5-trioxane with styrene, styrene oxide, and 1,3-dioxolane. These polyacetal-grafted carbon whi...
TL;DR: In this article, the lamination of composite elements such as sheets or fibres made from ceramic powders represents a cheap and easy way of making tough ceramics and the fabrication and failure behaviour of such layer...
Abstract: The lamination of composite elements such as sheets or fibres made from ceramic powders represents a cheap and easy way of making tough ceramics. The fabrication and failure behaviour of such layer...
TL;DR: In this article, the effect of functionalized short poly(ethylene-terephthalate) (PET) fibres, with free sulphonil azide groups, on the mechanical behaviour of low density polyethylene (LDPE) and polypropylene (PP) and their blends has been investigated by means of an experimental design.
Abstract: The effect of functionalized short poly(ethylene-terephthalate) (PET) fibres, with free sulphonil azide groups, on the mechanical behaviour of low density polyethylene (LDPE) and polypropylene (PP) and their blends has been investigated by means of an experimental design. The addition of modified PET fibres to these polymer matrices gives rise to a considerable increase in the tensile and tlexural moduli, mainly in matrices with high LDPE percentages. The strength of the composites depends principally on matrix composition. So fibres act as a reinforcing agent in matrices with high LDPE contents. However, at PP percentages above 60% in the matrix the tensile and flexural strengths decrease or remain almost constant as fibre content increases, respectively. The impact strength mainly depends on matrix composition although a minimum is observed at high both PP and fibre percentages in the composite. A comparison between natural and modified PET fibres has been carried out and the most important effect of th...
TL;DR: In this article, the interface between a polymer matrix and silica particles and two polymer components in a polymer blend was studied using nuclear magnetic resonance (NMR) in order to study the interaction between the two materials.
Abstract: Nuclear magnetic resonance is used to study the interface between (i) a polymer matrix and silica particles and (ii) two polymer components in a polymer blend.
TL;DR: In this article, a new induction time quantitative approach is applied to the transcrystalline growth of polyphenylene sulfide (PPS) spherulites on the surface of carbon fibers.
Abstract: Composite films of different molecular weight poly(phenylene sulfide) (PPS) and three types of carbon fibers (Pitch, PAN, and Rayon-based fibers) have been studied by optical microscopy and wide-angle X-ray diffraction. Transcrystallization of growing spherulites on carbon fibers is found under all thermal conditions of growth on Rayon and Pitch-based carbon fibers for all types of matrices. For composite films with PAN carbon fibers transcrystallization of growing spherulites is not uniform and sometimes is not found at all. Existence of b axial orientation of twisted lamellae for transcrystalline zone of PPS is demonstrated by X-ray diffraction technique and compared with orientation of the stretched sample. The new induction time quantitative approach is applied to the transcrystalline growth of PPS spherulites on the surface of carbon fibers. The interfacial free energy difference for fiber/crystallite and heterogeneities/ crystallite systems in the melt that is defined from growth and nucleation stud...
TL;DR: In this article, a double cantilever beam (DCB) test was carried out on glass epoxy laminate composites, using b-SGSi glass fabrics and standard glass fabrics.
Abstract: Glass fabric was treated with sol-gel transition silicate gel to modify the composite interface. Micro roughness on the surface of the glass fabric was observed clearly by the atomic force microscope (AFM) at the surface of glass fabric which had been treated with a base catalytic silicate gel (b-SGSi). The specific surface area of this glass was 1.4 times that of the original glass fabric. The double cantilever beam (DCB) test was carried out on glass epoxy laminate composites, using b-SGSi glass fabrics and standard glass fabrics. In this test, the former laminate showed two fracture modes, stable and unstable crack growth, whereas the latter laminate showed only stable crack growth. In reference to the fracture toughness of the stable crack growth, the former laminate is about 1.4 times greater than that of the latter laminate. It was suspected that the difference was caused by the different interface bonding strength in the composite. The interfacial bonding was also tested by the soldering iron test ...
TL;DR: In this paper, an in situ Fourier transform near infrared technique has been used to examine monolayer and sub-monolayer level surfactant adsorption at the silica optical fiber/solution interface.
Abstract: The use of composite materials has increased considerably in the past 30 years. However, many of the molecular level processes occurring in the interfacial region have yet to be investigated. In this regard, an in situ Fourier transform near infrared technique has been demonstrated herein. This technique utilizes a seven-fiber bundle to examine monolayer and sub-monolayer level surfactant adsorption at the silica optical fiber/solution interface. It is felt that this technique will greatly increase the knowledge of the processes involved in the improvement of mechanical properties of silane treated composites.