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METAL-CONTAINING NANOPARTICLES IN A MALEINIZED POLYETHYLENE MATRIX AS NANOFILLERS FOR POLYPROPYLENE
N.I.Kurbanova, Z.N.Huseynova, N.Y.Ishenko, A.T.Aliyev, T.M.Guliyeva, S.K.Ragimova, S.A.Rzaeva
Azerbaijan Cjemical Journal , 2019, DOI: 10.32737/0005-2531-2019-1-54-58
Abstract: The effect of additives of metal-containing nanofillers including nanoparticles of zinc oxide stabilized on a polymer matrix of maleinized polyethylene on the properties of nanocomposites based on isotactic polypropylene by methods X-ray phase and thermogravimetric analyses was studied. The improvement of the strength and rheological indexes, as well as the thermooxidative stability of the nanocomposites obtained was revealed
Temperature window effect and its application in extrusion of ultrahigh molecular weight polyethylene
eXPRESS Polymer Letters , 2011, DOI: 10.3144/expresspolymlett.2011.66
Abstract: Ultrahigh molecular weight polyethylene (UHMWPE) was ram extruded using a temperature window effect. The extrusion pressure abruptly drops at a very narrow extrusion temperature window which is about 10°C higher than the theoretical melting point of orthorhombic polyethylene crystals under quiescent and equilibrium states. The correlation between extrusion pressure and parameters such as extrusion temperature, annealing condition, thermal history, piston velocity, L/D ratio of the die, and molecular weight of UHMWPE, was studied. The temperature window increases with molecular weight and is unaffected by thermal history and annealing. The stable extrusion pressure and the critical piston velocity decrease with the rise in the extrusion temperature. The flow resistance reversely depends on the L/D ratio of the die. This phenomenon is attributed to an extensional flow-induced chain alignment along the streamline, which results in the formation of a metastable mesophase with higher chain mobility.
GC-MS OF POLYETHYLENE AND POLYPROPYLENE THERMAL CRACKING PRODUCTS  [PDF]
Ladislav Soják,Robert Kubinec,Helena Jurdáková,Elena Hájeková
Petroleum and Coal , 2006,
Abstract: Low-density polyethylene and polypropylene were thermally decomposed individually in a batch reactor at 450°C as a recycling route from the aspect of the production of petrochemical feedstock. The resulting transformation liquid products were analysed by high resolution gas chromatographic-mass spectrometric analysis. More detailed separation of polyalkenes splitting compounds was achieved using high resolution GC (efficiencies up to 490 000 plates) than before. The GC-MS as well as the dependence of homomorphy factors and isopropyl group increments on the number of carbon atoms of alk-1-enes, alk-2-enes, alka- , -dienes and alkanes were used for identification of separated analytes.Thermal cracking of LDPE products in the range C5-C23 were characterized by quintets of peaks in the chromatogram which were assigned to n-alkanes, alk-1-enes, (E)-alk-2-enes, (Z)-alk-2-enes and alka- , -dienes with average quantitative ratio 1 : 1.2 : 0.07 : 0.05 : 0.08. In fraction up to n-C8 140 GC peaks were separated and identified, including around 30 acyclic octenes.In contrast to the polyethylene thermal cracking which yields products with straight-chain hydrocarbon structure, polypropylene cracking is characterized by the formation of compounds with branched and high prevailingly unsaturated hydrocarbon structure. The pretention of this analytical problem lies in stereoisomerism and corresponding multicomponentity of branched alkenes, alkadienes and alkanes in a broad range of carbon atoms number as main decomposition products of polypropylene. In the liquid fraction up to n-C8 84 peaks including around 40 acyclic octenes were identified. Other 149 GC peaks were analysed in the C9-C25 fraction with quantitative ratio of alkane : alkene : alkadiene equal to 1 : 17 : 4. High resolution GC allowed more detailed and more reliable analysis of multicomponent polyalkenes cracking products.
Multifractal analysis of the fracture surfaces of foamed polypropylene/polyethylene blends  [PDF]
Chuang Liu,Xiu-Lei Jiang,Tao Liu,Ling Zhao,Wei-Xing Zhou,Wei-Kang Yuan
Physics , 2008, DOI: 10.1016/j.apsusc.2008.11.014
Abstract: The two-dimensional multifractal detrended fluctuation analysis is applied to reveal the multifractal properties of the fracture surfaces of foamed polypropylene/polyethylene blends at different temperatures. Nice power-law scaling relationship between the detrended fluctuation function $F_{q}$ and the scale $s$ is observed for different orders $q$ and the scaling exponent $h(q)$ is found to be a nonlinear function of $q$, confirming the presence of multifractality in the fracture surfaces. The multifractal spectra $f(\alpha)$ are obtained numerically through Legendre transform. The shape of the multifractal spectrum of singularities can be well captured by the width of spectrum $\Delta\alpha$ and the difference of dimension $\Delta f$. With the increase of the PE content, the fracture surface becomes more irregular and complex, as is manifested by the facts that $\Delta\alpha$ increases and $\Delta f$ decreases from positive to negative. A qualitative interpretation is provided based on the foaming process.
Mechanical and Morphological Properties of Polypropylene/Polyoxymethylene Blends  [PDF]
Sirirat Wacharawichanant, Tanakorn Siripattanasak
Advances in Chemical Engineering and Science (ACES) , 2013, DOI: 10.4236/aces.2013.33026
Abstract:

This work studies the mechanical and morphological properties of polypropylene (PP)/polyoxymethylene (POM) blends. The PP/POM blends were prepared by melting-blend with an internal mixer. The contents of PP were used at 10%, 20%, 30%, 70%, 80% and 90% by weight. The phase morphology of the blends was observed by scanning electron microscope (SEM) due to the mechanical properties depended on the phase morphology. The results show the decrease of the impact strength, Young’s modulus and tensile strength of POM/PP blends with increasing of PP content up to 30 wt% and then increase again with a high PP content. The percent strain at break of the blends increases after adding PP in a range of 70 - 90 wt%. SEM study reveals that the POM/PP blends clearly demonstrate a two-phase matrix-particle microstructure. The results also show that the domain size of dispersed PP or POM phase increases with increasing PP or POM content. The POM domain size is smaller than the PP domain size which leads to a little change of mechanical results of PP.

Investigation of MWCNT Reinforcement on the Strain Hardening Behavior of Ultrahigh Molecular Weight Polyethylene  [PDF]
Hassan Mahfuz,Mujibur R. Khan,Theodora Leventouri,Efthymios Liarokapis
Journal of Nanotechnology , 2011, DOI: 10.1155/2011/637395
Abstract: We have investigated strain hardening behavior of ultrahigh molecular weight polyethylene (UHMWPE) reinforced with 2.0?wt% loading of multiwalled carbon nanotubes (MWCNTs). A solution spinning process was used to produce neat and MWCNT-reinforced filaments of UHMWPE. Tensile tests of filaments showed 62% and 114% improvement in strength and modulus, respectively. Strain hardening tests on filaments revealed spectacular contribution by MWCNTs in enhancing strength and modulus by more than one order of magnitude. SEM micrographs showed sufficient coating of nanotube surface with the polymer that promoted interface adhesion. This intimate interfacial interaction enforced alignment of nanotubes during repeated loading-unloading sequences and allowed effective load transfer to nanotubes. Close interaction between UHMWPE and nanotubes was further evidenced by Raman spectral distribution as a positive shift in the D-band suggesting compressive stress on nanotubes by lateral compression of polymer. Nanotubes thus deformed induced the desired strain hardening ability in the UHMWPE filament. Differential scanning calorimetry (DSC) tests indicated around 15% increase in crystallinity after strain hardening—which together with nanotube alignment resulted in such dramatic improvement in properties. 1. Introduction UHMWPE is regarded as one of the most promising high performance fibers because of its low density, excellent strength to weight ratio, and outstanding impact property. Applications of this fiber have significantly increased in recent years in defense industries in manufacturing light weight ballistic plates, bulletproof helmet and vest, and shielding for armored vehicles. It is also used in composite materials for aviation and space flights, ropes for navy vessels, and in sports equipments. Such synthetic fibers typically need to have adequate tensile strength, high modulus, and long-term structural stability to satisfy a wide range of performance criteria. Its molecular chain can consist of as many as 200000 ethylene (–CH2–) repeat units forming a linear structure with a molecular weight of 3 to 6 million g/mole [1, 2]. In recent years it has been convincingly shown that inclusion of nanotubes can significantly influence the tensile properties of thermoplastic polymers including UHMWPE. [3, 4]. At identical draw ratio (~30) the strength and modulus of UHMWPE can be increased by 19% and 12%, respectively when, reinforced with 5?wt% of MWCNTs [5]. It has also been revealed that the ability of the polymer fibrils to undergo molecular orientation through
Thermal, mechanical and morphological properties of polypropylene/clay/wood flour nanocomposites
eXPRESS Polymer Letters , 2008, DOI: 10.3144/expresspolymlett.2008.11
Abstract: Nanocomposites with polypropylene/clay/wood flour were prepared by melt compounding. Thermal, mechanical and morphological properties were characterized. The addition of clay, compatibilizer and wood flour considerably improved the thermal stability (i.e., decomposition and melting temperatures) of the hybrids. The tensile modulus and strength of most hybrids were highly increased with the increased loading of clay, MAPP and wood flour, compared to the hybrids without wood flour. The wide angle X-ray diffraction (WAXD) patterns showed the increased d-spacing of clay layers, indicating enhanced compatibility between PP and clay with the addition of maleated polypropylene (MAPP). The transmission electron microscopy (TEM) photomicrographs illustrated the intercalated and partially exfoliated structures of the hybrids with clay, MAPP and wood flour.
Mechanical and morphological characterization of polypropylene toughened with olefinic elastomer
Lotti, Cybele;Correa, Carlos A.;Canevarolo, Sebasti?o V.;
Materials Research , 2000, DOI: 10.1590/S1516-14392000000200007
Abstract: the effect of incorporating (c2-c8) ethylene-octene elastomer on the mechanical properties and morphology of polypropylene copolymers has been investigated employing two types of pp copolymer, with and without nucleating agent. the results were compared to the ones presented by a commercial pp heterophase (reactor impact modified pp/epr). the addition of the elastomer increases the toughness of the blends but reduces their stiffness. pp blends in the low elastomer content region (< 20%) show low values of the izod impact strength and both, elastomer content and impact strength, are directly proportional to the area under the b damping peak or its maximum intensity of the elastomer. the morphology is a continuous pattern of segregate elastomeric particles with average particle size in the range of 0.27 mm to 0.39 mm. the average particle size and particle size distribution plotted in log-normal distribution curves, increases slightly with the increase in the elastomer content. the reactor modified pp heterophase has a broader particle size distribution and an average particle size of 0.56 mm, at the lower limit but inside the range for good impact performance, as observed.
Mechanical and morphological characterization of polypropylene toughened with olefinic elastomer
Lotti Cybele,Correa Carlos A.,Canevarolo Sebasti?o V.
Materials Research , 2000,
Abstract: The effect of incorporating (C2-C8) ethylene-octene elastomer on the mechanical properties and morphology of polypropylene copolymers has been investigated employing two types of PP copolymer, with and without nucleating agent. The results were compared to the ones presented by a commercial PP heterophase (reactor impact modified PP/EPR). The addition of the elastomer increases the toughness of the blends but reduces their stiffness. PP blends in the low elastomer content region (< 20%) show low values of the Izod impact strength and both, elastomer content and impact strength, are directly proportional to the area under the beta damping peak or its maximum intensity of the elastomer. The morphology is a continuous pattern of segregate elastomeric particles with average particle size in the range of 0.27 mum to 0.39 mum. The average particle size and particle size distribution plotted in log-normal distribution curves, increases slightly with the increase in the elastomer content. The reactor modified PP heterophase has a broader particle size distribution and an average particle size of 0.56 mum, at the lower limit but inside the range for good impact performance, as observed.
Effect of Carbon Fillers in Ultrahigh Molecular Weight Polyethylene Matrix Prepared by Twin-Screw Extrusion  [PDF]
Luiz Felipe M. Rocha, Suellem B. Cordeiro, Leonardo C. Ferreira, Flávio James H. Ramos, Maria de Fátima Marques
Materials Sciences and Applications (MSA) , 2016, DOI: 10.4236/msa.2016.712066
Abstract: Oxidized (GO) and expanded (G-Exp) graphite were employed to prepare composites with ultrahigh molecular weight polyethylene (UHMWPE) matrix using masterbatches of polyethylene with different compositions. The materials and a blend of UHMWPE/HDPE were prepared by extrusion and their properties were evaluated. The effect of carbon fillers on the crystalline structure, thermo dynamic-mechanical (DMTA) and thermal properties (melting and crystallization temperatures) of the composites were discussed. The thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) measurements showed that the addition of masterbatch with GO and G-Exp significantly increased the crystallite size of composites, increasing the temperatures of melting, degradation, glass transition and the degree of crystallinity of polyethylene. DMTA analysis indicated the storage and loss moduli of composites in relation to neat UHMWPE, the blend and UHMWPE/composites. SEM micrographs showed a flatter, continuous and uniform surface meaning a compact lamellar structure. The present work resulted in interesting findings on the effects of GO on the crystalline structures, mechanical and thermal properties of UHMWPE, which can lead to generalizations useful for future work.
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