Effect of functional groups of modified polyolefins on the structure and properties of their composites with lamellar silicates
Dipartimento di Chimica e Chimica Industriale, Università di Pisa, via Risorgimento 35, 56126 Pisa, Italy Polymer International
(Impact Factor: 2.41).
11/2005; 54(11):1549 - 1556. DOI: 10.1002/pi.1881
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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Available from: Ahmet Kasgoz
- "Recently, the effects of various types of modified polypropylenes grafted with different groups such as diethyl maleate (DMA)  , sulfonated chlorine groups (SO 2 Cl) , glycidyl methacrylate (GMA), acrylic acid (AA) , and itaconic acid (IA)  on the nanocomposite formations have been reported. It was shown that each of these groups grafted onto the PP backbone create the interfacial interactions between the polymer and clay layers necessary for good clay dispersion into the PP phase. "
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ABSTRACT: In this study, the use of low molecular weight oxidized polyethylenes (OxPE) with different molecular weight and acid number as a new type of compatibilizer in low density polyethylene (LLDPE)/org-clay nanocomposite preparation was examined. Nanocomposites having 5 phr (part per hundred) org-clay were prepared by melt processing. The effect of compatibilizer polarity and clay dispersion on the thermal, mechanical and barrier properties of the nanocomposites was investigated. It was observed that oxidized polyethylenes created a strong interfacial interaction between the clay layers and polymer phase based on the analysis of the linear viscoelastic behavior of the samples by small amplitude oscillatory rheometry. We showed that physical performance of the nanocomposites is not only affected by clay dispersion but also both melt viscosity and polarity of the oxidized polyethylene compatibilizers. It was found that oxygen permeability values of the nanocomposite samples prepared with the oxidized polyethylenes were lower than that of a sample prepared with conventional compatibilizer, maleic anhydride grafted polyethylene (PE-g-MA).
Available from: Ali Durmus
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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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