Search results for "Composite"
showing 10 items of 4584 documents
Supramolecular silver polyoxometalate architectures direct the growth of composite semiconducting nanostructures.
2009
Nanosilver on a string: Crystalline silver polyoxovanadate supramolecular architectures are employed as precursors for the synthesis of composite nanowires (see scheme). The nanostructures are composed of semiconducting vanadium oxide which forms wires with high aspect ratios, and are embedded with metallic silver nanoparticles. © 2009 Wiley-VCH Verlag GmbH & Co. KCaA.
Olive mill wastewaters decontamination based on organo-nano-clay composites
2019
Abstract Green composites for environmental applications were successfully prepared by intercalation of the biosurfactant Quillaja saponin onto montmorillonite mineral clay on varying pH and surfactant/clay ratio. Equilibrium adsorption isotherms were constructed and the system was characterized by performing TGA and XRD analyses. The efficiency of the surfactant-modified clay in the removal of the organic content present in olive mill wastewaters (OMW) was evaluated by means of spectrophotometric measurements. The interest for this cogent issue comes from the consideration that, despite their high pollutant content, OMW can be considered as a potential resource of several organic compounds…
In-line monitoring of the photooxidation behaviour of a PP/clay nanocomposite through creep measurements
2016
Abstract The photooxidation behaviour of a polypropylene/organomodified clay nanocomposite sample has been monitored by means of a new apparatus through the record of the creep curves measured while the sample is subjected to the contemporary action of temperature, tensile strength and UV radiation. The creep curves of the irradiated samples are higher than those of the non-irradiated samples and the curves diverge when the molecular weight begins to decrease because of the degradation. At the same the formation of carbonyl groups is observed. The creep curves of the non-irradiated and irradiated samples give, then, an immediate evaluation of the begin and of the development of the photooxi…
An Innovative Friction Stir Welding Based Technique to Produce Dissimilar Light Alloys to Thermoplastic Matrix Composite Joints
2016
Abstract Aluminum sheets can be joined to composite materials with different techniques. Each of them has advantages and weak points over the others. In literature, new techniques and patents are continuously developed to overcome these difficulties. In the paper a new Friction Stir Welding based approach is proposed to mechanically join AA6082-T6 to self-reinforced polypropylene. The aluminum sheet is pre-holed along both the sides of the weld line. A pinless tool generates the heat and pressure needed to activate back-extrusion of the composite. Joints have been produced with varying hole diameter and pitch. The mechanical resistance of the joint has been evaluated and the different failu…
Hygrothermal effect on moisture kinetics and mechanical properties of hemp/polypropylene composite: Experimental and numerical studies
2015
The exposition of thermoplastic composites reinforced with natural fibers to moisture and heat is likely to lower their mechanical properties and restrain their use in the design of parts. The present work is focussed on investigating the effects of hygrothermal aging on the mechanical behaviour of injected polypropylene reinforced with short hemp fibers. Moreover, the kinetic of isothermal moisture absorption has been studied for four immersion temperatures. The experimental results show that the time taken to reach saturation decreases significantly with increase in immersion temperature. These tests also reveal that moisture absorption in this type of materials does not follow Fick's law…
FEM Simulation of Laminated Lightweight Materials Processed through Single Point Incremental Forming
2015
The aim of present paper is to realize the FEM simulation of laminated lightweight material processed through single point incremental forming. Thus a laminated material, aluminum - polypropylene - aluminum (Al-PP-Al), as sheet 1.2 mm thickness was used. For these material the hardening curve was determinate. These values were used to describe elastic-plastic behavior of the material during single point incremental forming process simulation. Single point incremental forming process simulation aimed to assess the distribution of values and maximum and minimum strains, the material thickness of the specimen and the technological force for the two strategies for obtaining the truncated cone s…
Recycling of compatibilized and uncompatibilized nylon/polypropylene blends
2001
The recycling of compatibilized and uncompatibilized nylon6/polypropylene blends has been carried out by repetitive extrusions. The change of the properties of the blends is a function not only of the number of reprocessing steps but also of the type of compatibilizer. The worsening of the mechanical properties is small and, indeed, some improvement can be observed after one or two extrusion steps for some blends. It is hypothesised that the decrease of the molecular weight, the typical effect occurring during this thermomechanical treatment, is counterbalanced and overcome by the possible formation of new copolymers that act as bridges between the two phases. This behaviour is displayed by…
Model of the mechanical response of short flax fiber reinforced polymer matrix composites
2011
Abstract Natural-fiber-reinforced short-fiber composites are finding more applications lately, therefore there is a need for estimation of the mechanical properties of such composites based on the properties of the constituents. The fibers themselves also possess complicated internal structure, resulting in anisotropy of their properties. Taking into account the internal structure of bast fiber, we evaluate the elastic properties of a composite unit cell, consisting of a fiber of average length and matrix according to the fiber volume fraction in the composite. The unit cell properties are used to estimate the stiffness of a misaligned short-fiber composite by means of orientation averaging…
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…
Processing-property relationships of polypropylene/ciprofloxacin fibers
2015
In this work we prepared polypropylene (PP) fibers incorporating an antibiotic, i.e. ciprofloxacin (CFX), by melt spinning. In particular, PP has been compounded with CFX at different concentrations by using a counter-rotating twin screw compounder. The PP/CFX fibers have been spun by using a capillary rheometer operating under a constant extrusion speed. The effect of “online” hot drawing during the melt spinning or of an “offline” cold drawing on the properties of PP/CFX fibers were evaluated. In particular, the influence of the drawing conditions on the mechanical properties and the release kinetics were studied. Moreover, the rheological behavior in non-isothermal elongation flow has be…