Search results for "polypropylene"
showing 10 items of 177 documents
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…
Simultaneous application of vacuum and sweep gas in a polypropylene membrane contactor for the recovery of dissolved methane from water
2021
Abstract Vacuum and nitrogen as sweep gas were used simultaneously (combination mode) to generate the driving force in a microporous polypropylene membrane contactor for the recovery of dissolved methane from water. Experiments were carried out under different liquid flow-rates (5.0–28.0 L h−1), N2 flow-rates (0.5–1.5 L h−1) and vacuum pressures (0–480 mbar). The maximum removal efficiency of methane was >90% at moderate values of gas-to-liquid ratios (G/L) and vacuum of 0.2 and ≤ 200 mbar, respectively. Removal efficiencies obtained in combination mode were usually higher than when using vacuum or sweep gas, separately. To achieve a methane content >35% in the recovered gas, G/L values low…
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…
Synthesis of PP-LCP graft copolymers and their compatibilizing activity for PP/LCP blends
1998
The aim of this work was the synthesis of new graft copolymers consisting of polypropylene (PP) backbones and liquid crystalline polymer (LCP) branches, to be used as compatibilizing agents for PP/LCP blends. The PP-g-LCP copolymers have been prepared by polycondensation of the monomers of a semiflexible liquid crystalline polyester (SBH 1 : 1 : 2), that is, sebacic acid (S), 4,4′-dihydroxybiphenyl (B), and 4-hydroxybenzoic acid (H) in the mole ratio of 1 : 1 : 2, carried out in the presence of appropriate amounts of a commercial acrylic-acid-functionalized polypropylene (PPAA). The polycondensation products, referred to as COPP50 and COPP70, having a calculated PPAA concentration of 50 and…
Structure of isotactic polypropylene/ hydrogenated oligo(cyclopentadiene) blends: 1. Polypropylene-rich blends
1998
Blends of isotactic polypropylene (iPP) and hydrogenated oligo(cyclopentadiene) (HOCP) containing 30% or less HOCP have been studied by small-angle X-ray scattering in the temperature range 25 to 160°C. The structure of blends has been analysed in terms of a pseudo two-phase model consisting of stacks of lamellae whose thickness is a function of temperature and composition. Structural parameters of the model have been derived and their temperature and composition dependences have been interpreted in the light of existing theories.
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…
Necking behavior of low-density polyethylene-isotactic polypropylene blends: A morphological investigation
1984
The tensile behavior of low-density polyethylene-isotactic polypropylene blends was investigated at room temperature. Neck formation and propagation along the whole length of the samples were observed for the whole range of composition. This behavior, which is not indicated by most data available in the literature, was examined in relation to sample morphology by scanning electron microscopy. The results of this investigation indicated some differences between the morphology of these materials and the morphology of blends which do not undergo necking propagation.