1,720,974 research outputs found
Thermal Behaviour of Polymer/Cellulose Fibre Composites. Effect of Chemical Modification and Interfacial Interactions,
No full textThermal and Dynamic Mechanical Analysis of Polycarbonate-Linear Low Density Polyethylene Blends
No full textDeterminazione del contenuto di unità eseniche in copolimeri (Etilene/1-Esene) mediante microspettroscopia FT-IR
No full textProperty tuning of poly(lactic acid)/cellulose bio-composites through blending with modified ethylene-vinyl acetate copolymer
No full textThe effect of addition of an ethylene-vinyl acetate copolymer modified with glycidyl methacrylate (EVA-GMA) on the structure and properties of poly(lactic acid) (PLA) composites with cellulose micro fibres (CF) was investigated. Binary (PLA/CF) and ternary (PLA/EVA-GMA/CF) composites obtained by melt mixing in Brabender mixer were analysed by SEM, POM, WAXS, DSC, TGA and tensile tests. The miscibility and morphology of PLA/EVA-GMA blends were first examined as a function of composition: a large rise of PLA spherulite growth rate in the blends was discovered with increasing the EVA-GMA content (0-30 wt%) in the isothermal crystallization both from the melt and the solid state. PLA/EVA-GMA/CF ternary composites displayed improved adhesion and dispersion of fibres into the matrix as compared to PLA/CF system. Marked changes of thermodynamic and tensile parameters, as elastic modulus, strength and elongation at break were observed for the composites, depending on blend composition, polymer miscibility and fibre-matrix chemical interactions at the interface.Fil: Pracella, Mariano. Istituto per i Polimeri, Compositi e Biomateriali; ItaliaFil: Haque, Md Ahsanul. Università degli Studi di Pisa; ItaliaFil: Paci, Massimo. Università degli Studi di Pisa; ItaliaFil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin
“ Polymer composites with HEMP fibres: compatibilization, Morphology, Thermal And mechanical properties
No full text
FTIR Microanalysis and Phase Behaviour of Ethylene/1-Hexene random copolymers
No full textEthylene/1-hexene random copolymers with 1-hexene content in the range of 1-5 mol-%, synthesised in the presence of new heterogeneous catalyst systems based on bis-carboxylato and -bis-chloro-carboxylato titanium chelate complexes, have been characterised by FTIR microspectroscopy (FTIR-M), DSC calorimetry and X-ray scattering. The co-monomer content and sequence distribution in the various samples were determined by means of both FTIR-M and C-13 NMR spectroscopy. The deformation bands of methyl groups in the region of 1400-1330 cm(-1) were used for the structural analysis of these copolymers. The effect of composition on the crystallinity and phase transitions of copolymers was analysed both in 1500-1300 and 760-690 cm(-1) frequency ranges as a function of the annealing temperature. A neat variation of the absorbance ratio of methyl band at 1378 cm-1 was recorded between 110 and 130 degrees C corresponding to the melting range of the copolymer crystals. The crystallisation behaviour of the copolymers was examined by DSC in dynamic and isothermal conditions; the isothermal kinetics were analysed according to the Avrami model. A marked decrease in the bulk crystallisation rate, accompanied by changes in the nucleation and growth of crystals, was found with an increase in the co-monomer content. The melting behaviour of isothermally crystallised samples was also investigated and the melting temperatures of the copolymers at equilibrium conditions were related to the composition; the experimental data were consistent with the Flory exclusion model of side branches from the crystalline phase. The lowering of crystal growth rate in the copolymers has been accounted for by an increase in the free energy of formation of critical size nuclei due to the effect of the side branches
Preparation and Properties of Biodegradable Polymer/Polyolefin-Natural Fibers Ternary Composites Systems,
No full textLinear low-density polyethylenes by co-polymerization of ethylene with 1-hexene in the presence of titanium precursors and organoaluminium co-catalysts
No full textThe co-polymerization of ethylene with 1-hexene has been performed with titanium precursors based on carboxylato ligands in the presence of organoaluminium compounds as activators to afford linear low-density polyethylenes (LLDPEs). The influence of the polymerization parameters was studied with particular reference to the type and amount of catalyst components, solvent, temperature, ethylene pressure, 1-hexene concentration. The chloro-substituted bis-carboxylato titanium complex resulted the most active precursor in the co-polymerization, allowing to obtain copolymers with modulable composition in the 1-5 mol% range of 1-hexene units. The obtained copolymers were characterized by thermal analysis, X-ray diffraction spectroscopy, FTIR and NMR techniques. (c) 2007 Elsevier Ltd. All rights reserved
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