Impact à faible vitesse sur un composite polypropylène/fibre de verre

Définitions d'impact a faible vitesse -- Test d'impact à faible vitesse -- Contraintes et déformation associées à l'essai du poids tombant -- Endommagement causé par impact -- Propriétés résiduelles -- Influence des constituants -- Essais d'impact instrumentés -- Taux de relâchement d'énergie -- Matériaux utilisés et condition de moulage -- Essais d'impact -- Influence de la largeur des échantillons sur l'impact -- Caractérisation de l'endommagement -- Détermination des propriétés résiduelles après impact -- Détermination du taux de relâchement d'énergie -- Influence de la largeur des échantillons -- Caractérisation de l'endommagement -- Analyse des signaux d'impact -- Propriétés résiduelles après impact -- Détermination du taux de relâchement d'énergie -- Influence de la largueur des échantillons -- Etat de contrainte et endommagement -- Evolution de l'endommagement -- Propriétés résiduelles après impact -- Valeurs critiques pour l'initiagion de la délamination -- Détermination du taux de relâchement d'énergie

Experimental investigation on the consolidation of polypropylene-clay nanocomposite fibers

Peer reviewed: YesNRC publication: Ye

Experimental investigation on the consolidation of polypropylene-clay nanocomposites fibers

Peer reviewed: YesNRC publication: Ye

Polypropylene fibers nanocomposite: Properties, Structure and Process Parameters

Peer reviewed: YesNRC publication: Ye

Microtomographic Analysis of Impact Damage in FRP Composite Laminates: A Comparative Study

With the advancement of testing tools, the ability to characterize mechanical properties of fiber reinforced polymer (FRP) composites under extreme loading scenarios has allowed designers to use these materials in high-level applications more confidently. Conventionally, impact characterization of composite materials is studied via nondestructive techniques such as ultrasonic C-scanning, infrared thermography, X-ray, and acoustography. None of these techniques, however, enable 3D microscale visualization of the damage at different layers of composite laminates. In this paper, a 3D microtomographic technique has been employed to visualize and compare impact damage modes in a set of thermoplastic laminates. The test samples were made of commingled polypropylene (PP) and glass fibers with two different architectures, including the plain woven and unidirectional. Impact testing using a drop-weight tower, followed by postimpact four-point flexural testing and nondestructive tomographic analysis demonstrated a close relationship between the type of fibre architecture and the induced impact damage mechanisms and their extensions

Investigation of a postprocessing method to tailor the mechanical properties of carbon nanotube/polyamide fibers

The incorporation of carbon nanotubes to thermoplastic fibers can potentially improve mechanical, thermal and electrical properties. In this article, a methodology to tailor the mechanical properties of carbon nanotube/nylon fibers is presented. Multiwalled nanotubes (MWNT) were combined to polyamide 12 through melt compounding and twin-screw extrusion. Pellets containing between 0 and 5.0 wt % MWNT were extruded and subsequently melt spun with a capillary rheometer to produce filaments. To further promote the alignment of the polymer chains and MWNTs, postdrawing parameters were systematically investigated: temperature, drawing speed and elongation. The best improvements in terms of elastic modulus and yield strength were measured at 140\ub0C and 500% elongation, whereas drawing speed was shown to have a negligible effect. It was confirmed through electron microscopy and X-ray diffraction that these enhancements were mainly induced by the alignment of the polymer chains along the fibers' axis. Copyright \ua9 2013 Wiley Periodicals, Inc.Peer reviewed: YesNRC publication: Ye

Influence of cooling rates on microstructure and mechanical performance of continuous fiber reinforced PPS composites

In this study, the influence of the cooling rate on the crystallization temperature, level of crystallinity, spherulite size and mechanical properties was investigated for two continuous fibers reinforced polyphenylene sulfide (PPS) composites. Crystallization temperature and level of crystallinity were first studied by differential scanning calorimetry (DSC) for cooling rates comprised between 5 and 70\ub0C/min. Results obtained showed that level of crystallinity was not significantly influenced by the cooling rate, while crystallization temperature decreased with increasing cooling rate. Matrix microstructure and composite short beam shear strength were then characterized for cooling rates of 3, 15 and 20\ub0C/min. These cooling rates were chosen because they are representative of cooling rates used in autoclave manufacturing and compression molding. To enhance the microstructure of the PPS matrix, an etching solution based on potassium permanganate and orthophosphoric acid was used.Peer reviewed: YesNRC publication: Ye