Search results for "Modulus"
showing 10 items of 491 documents
DEGRADATION OF MATER-BI /WOOD FLOUR BIOCOMPOSITES IN ACTIVE SEWAGE SLUDGE
2009
The mechanical properties of Mater-Bi® are, in general, not adequate for certain applications and the addition of a filler is therefore necessary. Among the different fillers, natural fibres are particularly interesting because they potentially allow improving the performance of the material without compromising its biodegradability. In order to improve the basic mechanical properties of a Mater-Bi grade and to obtain a new, fully biodegradable material, wood flour based composites were prepared by different processing methods. To simulate actual and not laboratory bacterial attack on the prepared materials, in this work we studied the biodegradation of the composites in a real active sewag…
Properties evolution of flax/epoxy composites under fatigue loading
2014
International audience; The tension-tension fatigue behaviour of flax fibre reinforced epoxy matrix composites have been investigated for specimens having [0]12, [90]12, [0/90]3S and [±45]3S lay-ups. The Probabilized Stress-Number of cycles (P-S-N) curves have been determined for each laminate type. The measured stress and strain data allowed to quantify the evolution of the mechanical properties, i.e. stiffness, damping and permanent strain as a function of imposed cycles. Especially, the stiffening phenomenon of flax reinforcements oriented parallel to the loading direction has been confirmed. However, due to the competition between damage development and the fibre stiffening, the increas…
TOWARD A DESIGN METHOD FOR METAL-COMPOSITE CO-CURED JOINT BASED ON THE G-SIFs
2013
Abstract In this work, a systematic study of the singular stress field in the zone where the interface intersects the free edge surfaces of bonded metal-composite co-cured joints, has been performed. The obtained theoretical, numerical and experimental results have permitted to detect the relationships between the joint configuration and the singular stress field, as well as to implement a new design method based on the so called generalised stress intensity factors. Such a proposed method allows the user to predict the static strength of a generic metal-composite co-cured joint, vs. the main influence parameters as the elastic modulus of the coupled materials, the overlap length, the taper…
Preparation and mechanical properties of intercalated PP/OMMT nanocomposites
2007
The preparation of polymer nanocomposites by melt compounding polypropylene (PP) with organically modified montmorillonite using maleic anhydride modified PP as compatibilizer is described. Compositions with organomontmorillonite content 0, 5, 10 wt.% were prepared and tested. Data on the influence of organomontmorillonite content on the tensile stress?strain curves, elastic modulus, strength, and ultimate elongation of the nanocomposites are obtained. The concentration dependences of elastic properties of materials with differently oriented plate like nanoparticles analyses taking into account hierarchical structure features of nanocomposites is considered. Theoretical analysis results are…
Thermal and Mechanical Properties of Unvulcanized Polypropylene Blends with Different Elastomers: Ethylene-Propylene-Diene Terpolymer, Nitrile-Butadi…
2013
In this work, composites of isotactic polypropylene (PP) with three unvulcanized elastomers – terpolymer of ethylene-propylene-dicyclopentadiene (EPDM), chlorinated polyethylene (CPE) and copolymer of acrylonitrile-butadiene (NBR) – have been investigated. The purpose of the investigation was to create PP/elastomer blend composites of significantly different compositions (with an excess of PP, intermediate ones, and with an excess of elastomer) and to study the dependence of tensile behaviour and elastic properties on the blends with different component ratio. Tensile properties have been recognized from the stress-strain curves. The changes of elastic modulus have been characterized with r…
Structure and Mechanical Properties of Melt Intercalated Po1lypropylene–Organomontmorillonite Nanocomposites
2010
The preparation and properties of polymer nanocomposites, obtained by melt-compounding of polypropylene (PP) and organomontmorillonite (OMMT) modified by different alkyl ammonium salts, are described. A copolymer of maleic anhydride and PP was used as a compatibilizing additive. Nanocomposites with OMMT content of 1, 5 and 10 wt% were prepared and tested. The influence of OMMT content on the tensile stress–strain curves, elastic modulus, yield and tensile strength, and ultimate elongation of the nanocomposites is determined. The results of measuring the microhardness and impact strength of polymer nanocomposites are presented. Long-term creep tests were performed to predict the long-term de…
Accelerated weathering of polypropylene/wood flour composites
2008
Abstract Wood–plastic composites (WPCs) have received increasing attention during the last decades, because of many advantages related to their use. Some of their main applications are represented by outdoor furnishing and decking; therefore, it is important to assess their behaviour under UV exposure. In this work, polypropylene/wood flour composites were prepared and their resistance to photooxidation investigated. The composites were prepared by extrusion and compression moulding, and were subjected to mechanical tests, FTIR analysis and molecular weight measurements. The results showed that the composites retained a higher fraction of the original mechanical properties after accelerated…
Characterization of blends of polypropylene with a semirigid liquid-crystal copolyester
1991
Abstract Blends with a liquid-crystal polymers (LCP) as one component show, in general, very interesting properties. Reduction of shear viscosity and improvement of mechanical properties are very remarkable. High melting temperatures and high costs of the LCP limit the use of these blends. A new class of thermotropic LCPs with flexible spaces, with relatively low melting temperatures, can overcome the first problem. In this work, rheological and mechanical properties of blends of polypropylene with low contents of this LCP are presented. Torque during extrusion and viscosity decrease with LCP content. Elastic modulus is remarkably increased when the LCP phase is oriented.
Modeling elastic properties of short flax fiber-reinforced composites by orientation averaging
2010
Abstract Natural fibers of plant origin, used as reinforcement in polymer matrix composite materials, exhibit highly anisotropic elastic properties due to their complex internal structure. Mechanical properties can be evaluated not only by tests but also by mechanical models reflecting the principal morphological features of fibers. Such a FEM model is applied to estimate the elastic properties of a unit cell of a short-fiber-reinforced composite, an elementary flax fiber embedded in a polymer matrix. Orientation averaging approach is used for prediction of the stiffness of short flax fiber reinforced polymer matrix composite. The numerical estimates of Young’s modulus are compared to the t…
“Effect of Filler Type and Processing Apparatus on the Properties of the Recycled “Light Fraction” from Municipal Post-Consumer Plastics”
2001
Plastic waste or scraps are generated from two main sources: industrial wastes and post-consumer wastes. By using the flotation method, generally two fractions are obtained from municipal post-consumer wastes: a light fraction, floating on water, and a heavy fraction. The former is essentially made of low and high density polyethylene—LDPE, HDPE—and polypropylene—PP; the heavy fraction is formed by poly(vinyl chloride)—PVC—and poly(ethylene terephthalate)—PET. In this work, the recycling of a light fraction from municipal post-consumer plastics has been studied, considering also the effect of filler type—glass fibres, calcium carbonate and wood fibres—and processing apparatus—discountinous …