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WOS: 000519806700073, In this study, composites composed of glass fiber reinforced-epoxy laminates interleaved with electrospun polyvinylchloride (PVC) nano-fibres were designed for radar absorption investigations. The laminated composites which were produced in special molds were obtained by placing woven glass fibers between each of PVC nanofiber mats, and the composites were produced in three different forms as pure, multi-walled carbon nanotubes doped and graphene doped. The morphologies of the PVC nanofiber mats were analyzed by scanning electron microscope. The radar absorption efficiencies of the composites in the individual and different combinations were measured in the 3-8 GHz frequency band. Experimental results show that the produced graphene-added composite material has improvable microwave absorption effect at several points in 3-8 GHz band to provide excellent absorption in future studies. The graphene doped structure was found to have a certain absorption characteristic up to 33.82% at a constant frequency. Besides, various strong absorption frequency points have been obtained in the related frequency range. The cascaded graphene doped composite layers can provide broadband absorption for stealth technology.

Presently, fiber reinforced materials are used for many industrial applications. Laser transmission welding (LTW) is a suitable method to join these materials. For multiple thermoplastics, the weld seam quality is affected by the amount of moisture content in the joining members. For LTW, heat is applied to the welding members and water in the composite changes phase from liquid to gas. Increasing the gas content can lead to detrimental cavities in the weld seam. Therefore, experiments were performed to investigate the influence of the laser focal geometry on the generation of cavities. Different focal geometries lead to different levels of process heat generation which affects the amount of vaporization. The experiments were conducted with endless glass fiber reinforced polyetherimide and endless carbon fiber reinforced polyetherimide. These samples were tested for their weld seam strength and the results were correlated to the moisture content and laser beam geometry. © 2016 The Authors.

The development of single mode chalcogenide glass fibers as wavefront filter for the DARWIN mission is reported. Melting procedures and different preform techniques for manufacturing core-cladding chalcogenide fibers are described. Bulk glass samples on the basis of Te-As-Se- and high Te-compositions have been characterized optically, by measurement of the absorption spectrum and the refractive index in the region 4 – 20 μm. Several chalcogenide core-cladding glass fiber configurations have been drawn and examined by microscopy. The mode propagation behaviour and numerical aperture of fiber samples have been determined by far field intensity distribution measurements, using a CO2 laser at 10.6 μm. Single mode waveguide performance has been demonstrated for several fiber samples, coated with an absorbing Gallium layer for stripping of cladding modes.

cited By 11; International audience; The present paper investigates glass fibre flaw size distributions. Two commercial fibre grades (HP and HD) mainly used in cement-based composite reinforcement were studied. Glass fibre fractography is a difficult and time consuming exercise, and thus is seldom carried out. An approach based on tensile tests on multifilament bundles and examination of the fibre surface by atomic force microscopy (AFM) was used. Bundles of more than 500 single filaments each were tested. Thus a statistically significant database of failure data was built up for the HP and HD glass fibres. Gaussian flaw distributions were derived from the filament tensile strength data or extracted from the AFM images. The two distributions were compared. Defect sizes computed from raw AFM images agreed reasonably well with those derived from tensile strength data. Finally, the pertinence of a Gaussian distribution was discussed. The alternative Pareto distribution provided a fair approximation when dealing with AFM flaw size. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Injection molded polymer composite gears are being used in many power and motion transmission applications. In order to widen the utilization of reinforced polymers for precision motion transmission and noise less applications, the quality or accuracy of molded gears should be increased. Since the injection molded gear quality is significantly influenced by the material shrinkage behaviour, there is a need to understand the influence of fiber orientation on part shrinkage behaviour and hence the gear quality. Unreinforced and 20% short glass fiber reinforced Nylon 6/6 spur gears were injection molded in the laboratory and computer aided simulations of gear manufacturing was also carried out. Results of the mold flow simulation of gear manufacturing were correlated with the actual fiber orientation and measured metrological parameters of the molded gears. Actual orientation of the fibers near the tooth profile, weld line region and injection points of molded gears were observed using optical microscope. Fiber alignment along the tooth profile restricts shrinkage and induces anisotropic shrinkage, which significantly decreases the deviation of involute profile parameter from the design value. Fibers embedded in the molded skin surface increases the gear tooth profile form and lead form deviations. Non-alignment of fibers across the gear tooth section increases the tooth thickness, tooth-to-tooth spacing and radial runout deviations from design values. � 2007 Elsevier Ltd. All rights reserved.

Glass fiber reinforced vinyl ester polymer composites filled with clay particles were synthesized by a hand lay-up technique with the addition of methy ethyl ketone peroxide (MEKP), cobalt napthalate and benzoyl peroxide. Mechanical and thermal properties of vinyl ester-glass fiber composite and clay particles dispersed vinyl-glass fiber hybrids were investigated in the present work. The hybridization effect of nanoclay dispersion in vinyl ester-fiber composite was discussed. Enhanced mechanical, thermal and vibration properties were observed in nanoclay dispersed composites over vinyl ester-glass fiber composite. � SAGE Publications 2008.

We theoretically demonstrate a novel approach for generating Mid-InfraRed SuperContinuum (MIR SC) by using concatenated fluoride and chalcogenide glass fibers pumped with a standard pulsed Thulium (Tm) laser (TFWHM=3.5ps, P0=20kW, νR=30MHz, and Pavg=2W). The fluoride fiber SC is generated in 10m of ZBLAN spanning the 0.9–4.1μm SC at the −30dB level. The ZBLAN fiber SC is then coupled into 10cm of As2Se3 chalcogenide Microstructured Optical Fiber (MOF) designed to have a zero-dispersion wavelength (λZDW) significantly below the 4.1μm InfraRed (IR) edge of the ZBLAN fiber SC, here 3.55μm. This allows the MIR solitons in the ZBLAN fiber SC to couple into anomalous dispersion in the chalcogenide fiber and further redshift out to the fiber loss edge at around 9μm. The final 0.9–9μm SC covers over 3 octaves in the MIR with around 15mW of power converted into the 6–9μm range.

Fluoride phosphate (FP) glass fibres have been developed for radiation dosimetry based on the mechanism of optically stimulated luminescence (OSL). Doping with Tb3+ ions improved the materials sensitivity; for samples melted in oxidising conditions, OSL intensity was increased from 8:8 × 105 cnts/g/Gy for undoped glass to 812:3 × 105 cnts/g/Gy for Tb3+-doped glass. The radiation sensor performance of Tb3+-doped glass fibres under both beta and X-ray irradiation demonstrated the capability of the fibres for radiation dosimetry applications. Refereed/Peer-reviewed

International audience; Using short natural fibers in thermoplastic composites not only improves polymer mechanical properties, but also allows making materials that are lightweight compared to composites reinforced with glass fibers. The main applications are plastic parts for automobiles,packaging and construction.Natural fibers come from renewable resources, are cheap and easily available. However, there are a lot of morphology and properties differences between glass and natural fibers. Glass fibers have a homogeneous composition and diameter, are straight, stiff and brittle, but natural fibers usually have a various chemical compositions and appear as thick and stiff bundles and/or as thin flexible elementary fibers.During injection molding process, fibers are flowing and then, after material solidification, their dispersion and orientation are "frozen". While the microstructure of glass fibers reinforced thermoplastic is well known, natural fibers case is still not studied in details. Will natural fibers take the same orientation in the injected parts as glass fibers? How natural fibers flexibility influences their orientation? Do natural fibers remain curved in composites?The work objective is to analyze and to understand the microstructure of flax fiber-polymer-composite. Fibers were mixed with polypropylene in a twin screw extruder, pelletized and injected in a rectangular-shaped mold. By optical microscopy in transmitted and reflected light accompanied by image analysis, fiber orientation and curvature were quantified, at different depths and locations in the injected parts.Results were related with shear and elongation flows experienced by the material during processing.