Effect of functional groups of modified polyolefins on the structure and properties of their composites with lamellar silicates
ABSTRACT The melt mixing of functionalized polyolefins with a surface-modified layered silicate (montmorillonite) was investigated as an approach to prepare the corresponding micro/nanocomposites. The effect of the diethyl succinate groups, derived from the grafting of diethyl maleate (DEM) onto the polyolefins, on compatibility with an inorganic filler and the dispersion in a hydrophobic matrix was extensively investigated. In order to avoid possible interference by polymer multiphase morphology, the amorphous poly(propylene-ran-ethylene) (EPM) (70/30, wt/wt), functionalized with DEM (EPM-graft-DEM), was used in melt mixing with alkyl-ammonium-salt-modified montmorillonite at different weight ratios by using a Brabender mixer. Materials with a nanoscale dispersion of the inorganic phase, as revealed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses, were obtained. Specific interactions, involving the carbonyl groups of the polyolefin functional groups and the polar sites on the filler surface, appeared to assist intercalation and/or exfoliation of the layered system. Similar results were obtained by starting with an unfunctionalized EPM and by performing the grafting reaction with DEM during melt mixing according to a one-step simplified procedure. Copyright © 2005 Society of Chemical Industry
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ABSTRACT: In this work, high density polyethylene (HDPE)/organo-clay (Cloisite® 15A) nanocomposites were prepared by melt processing using a commercially available oxidized polyethylene/oxidized (ethylene-co-vinyl acetate) copolymer blend (30:70 wt%) (AC® 645 supplied from Honeywell) as compatibilizer. Clay and compatibilizer amounts were varied to optimize clay dispersion and property enhancement. Clay dispersion was investigated by X-Ray diffraction (XRD) method). Viscoelastic behavior of the nanocomposites was analyzed by a dynamic oscillatory rheometer in melt state. Oxygen permeability properties of the film samples, prepared by means of a hot compression, were tested with a gas permeability tester working by the constant volume/variable pressure method.
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ABSTRACT: The dispersion of organo-layered double hydroxides (O-LDH) in functionalized polyolefins (POs) is investigated. Two different polyethylene matrices (maleic anhydride (MAH) and diethyl maleate functionalized) are tested and a hydrogenated fatty acid modified LDH is used. The attention is focused on evidencing the interaction between the functional groups of the polymer and the O-LDH through FT-IR. Moreover, a combination of solvent fractionation, morphological, and rheological characterizations enables to gain a deeper insight into the structure of these composites. In particular, the formation of bridging bonds between the particles and MAH functionalized macromolecules is assumed, possibly due to the formation of ionic clusters, characteristics of ionomers, with formation of crosslinked/aggregated structures.Macromolecular Reaction Engineering 02/2014; 8(2). DOI:10.1002/mren.201300154 · 1.54 Impact Factor