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This study arises on the opportunities of using flax fibers as reinforcement for polypropylene (PP) matrix composites. For this purpose, untreated flax fiber bundles obtained by a retting process have been used. For improving compatibility between flax fiber bundles and PP matrix, fiber surface treatments such as maleic anhydride, maleic anhydride polypropylene copolymer, and vinyltrimethoxy silane have been carried out. On the other hand, alkali treatment has also been carried out for fiber modification. The effect of surface modification on tensile properties of single fibers and also on fiber-matrix interfacial shear strength (IFSS) has been analyzed. Finally, both optical microscopy and atomic force microscopy have been used for characterizing flax fiber microstructural features. The current study completes previous results to elucidate the influence of treatments on fiber surface and flax fiber-PP interface. POLYM. COM-POS., 26:324 -332, 2005.

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In this study, the influence of poly(ethersulfone) (PES) as a modifying agent of a tetrafunctional epoxy matrix (TGDDM) on the mechanical behavior of composite laminates based on woven carbon fibers has been investigated. Dynamic mechanical experiments were performed on neat matrix resins and on their corresponding laminate composites. Mode‐I and Mode‐II fracture toughness tests for the bulk matrices and their composites, respectively, and also flexural and short beam shear tests (SBS) were carried out. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to investigate the morphologies obtained. A nanoscopic phase separation was obtained after PES addition, which was not able to stabilize the fracture process, leading, as a consequence, to a poor extent of improvement on fracture toughness properties. Polym. Compos. 25:480–488, 2004. © 2004 Society of Plastics Engineers.

In the present work the effect of epoxy sizings on the fracture behavior of woven carbon fiber tetrafunctional epoxy composites has been investigated. Three‐point flexural, short beam shear (SBS) and Mode‐II interlaminar fracture toughness (ENF) tests have been carried out. Wettability and Atomic Force Microscopy (AFM) studies have been performed on commercial sized, desized and 0.7 wt% TGDDM and 0.7 wt% DGEBA sized carbon fibers. Dynamic mechanical thermal analysis and Scanning Electron Microscopy (SEM) studies were also carried out on the different carbon fiber/epoxy composites. The used sizing treatments provided composites with improved mechanical properties due to the enhancement achieved in the fiber‐matrix adhesion. Polym. Compos. 25:319–330, 2004. © 2004 Society of Plastics Engineers.