Search results for "SITE"
showing 10 items of 8388 documents
Rheological Properties of Different Film Blowing Polyethylene Samples Under Shear and Elongational Flow
2005
Summary: The rheological behavior of polyethylenes ismainly dominated by the molecular weight, the molecularweight distribution and by the type, the amount and thedistribution of the chain branches. In this work a linearmetallocenecatalyzedpolyethylene(m-PE),abranchedme-tallocene catalyzed polyethylene (m-bPE), a conventionallinear low density polyethylene (LLDPE) and a low densitypolyethylene (LDPE) have been investigated in order tocompare their rheological behavior in shear and in elonga-tional flow. The four samples have similar melt flow indexand in particular a value typical of film blowing grade.The melt viscosity has been studied both in shear and inisothermal and non-isothermal elonga…
Nanocomposites with polyhedral oligomeric silesquioxane nanofillers - characterization of morphology, thermal and mechanical properties
2016
High-density polyethylene nanocomposites with hydroxy-hepta(iso-butyl)-octasilsesquioxane (POSS-(i-Bu)7OH) and hydroxy-hepta(iso-octyl)-octasilsesquioxane (POSS-(i-Oct)7OH) as nanofillers were prepared by melt blending. The morphological, thermal and mechanical properties as well as processability of obtained nanocomposites were characterized. POSS nanofillers were homogenously dispersed in polymeric matrix. High compatibility between nanofiller and polymer induced enhanced thermal stability, Charpy impact strength and melt flow rate for composite materials. POSS particles acted also as a nucleating agent for polyethylene crystallization in the nanocomposite.
Low-temperature single crystal X-ray diffraction and high-pressure Raman studies on [(CH3)2NH2]2[SbCl5]
2007
The structure of bis(dimethylammonium) pentachloroantimonate(III), [(CH{sub 3}){sub 2}NH{sub 2}]{sub 2}[SbCl{sub 5}], BDP, was studied at 15 K and ambient pressure by single-crystal X-ray diffraction as well as at ambient temperature and high pressures up to 4.87(5) GPa by Raman spectroscopy. BDP crystallizes in the orthorhombic Pnma space group with a=8.4069(4), b=11.7973(7), c=14.8496(7) A, and Z=4; R{sub 1}=0.0381, wR{sub 2}=0.0764. The structure consists of distorted [SbCl{sub 6}]{sup 3-} octahedra forming zig-zag [{l_brace}SbCl{sub 5}{r_brace}{sub n}]{sup 2n-} chains that are cross-linked by dimethylammonium [(CH{sub 3}){sub 2}NH{sub 2}]{sup +} cations. The organic and inorganic substr…
Durability of multi-phase polymer based nanocomposites
2010
Influence of the morphology on the photo-oxidation behaviour of polymer based nanocomposites
2011
The use of in-line quantitative analysis to follow polymer processing
2009
In this work it is presented three applications of real time analysis during extrusion process using an optical device developed by our research group, which applies the concepts of light extinction. Monitoring of polymer blends morphology takes place to infer data concerned to dispersed phase size and concentration. The detector also enables information about melting temperature of polymer during extrusion and the level of viscous heating, and the exfoliation step during processing of a polymer-clay nanocomposite.
Effect of the processing on polyethylene/clay nanocomposites
2008
Characterization and biodegradability of biodegradable polymer-wood flour composites
2008
Functional Bionanocomposite Fibers of Chitosan Filled with Cellulose Nanofibers Obtained by Gel Spinning
2021
Extremely high mechanical performance spun bionanocomposite fibers of chitosan (CHI), and cellulose nanofibers (CNFs) were successfully achieved by gel spinning of CHI aqueous viscous formulations filled with CNFs. The microstructural characterization of the fibers by X-ray diffraction revealed the crystallization of the CHI polymer chains into anhydrous chitosan allomorph. The spinning process combining acidic–basic–neutralization–stretching–drying steps allowed obtaining CHI/CNF composite fibers of high crystallinity, with enhanced effect at incorporating the CNFs. Chitosan crystallization seems to be promoted by the presence of cellulose nanofibers, serving as nucleation sites for the gr…