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Polypropylene (PP) nanocomposites were prepared using montmorillonite with different organic modifiers, and the effect of processing aid (EMCA and PPG) on the dispersion of the nanofillers in the PP matrix was evaluated by WAXD, TEM, DSC, TGA, DMA, and mechanical tests. The present study helps to clarify the effects of the organic modifiers of clays on the intercalation and exfoliation processes. Nanocomposites of intercalated and partially exfoliated morphology were obtained, mainly when a low amount (1:1) of PP-g-MA/MMT was used. The results of the tests on mechanical properties showed that the clays with larger d 001 (C-15A and Nanofil 5) using PPG presented a more considerable gain in impact strength. The nanocomposites using clays with smaller d 001 (C-20A) presented larger modulus when compared with those of pristine PP. The heat deflection temperature, crystallization temperature, and thermal stability of the nanocomposites were improved compared to neat PP. The DMA results showed that the organoclay improved the modulus of PP, but decreased the T g .

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Poly(propylene-co-ethylene) composites with rice husk were prepared in a corotating intermeshing twin-screw extruder using four different coupling agents. While modified maleic anhydrides such as maleated polypropylene (MAPP) and maleated polyethylene (MAPE) are commonly used as compatibilizers to improve interfacial adhesion between lignocellulosic filler and matrix, in this study, polypropylene grafted with acid comonomer (CAPP) and high-density polyethylene grafted with acid comonomer (CAPE) were also used. The morphologies and the thermal and mechanical properties of the composites were characterized using scanning electron microscopy, thermogravimetric analysis, differential scanning analysis, tensile and impact tests. The results indicate that the base resin of the compatibilizer is an important factor in determining the effectiveness of compatibilizers for composites. Composites with PP-based compatibilizers are more effective than PE-based compatibilizers due to the improved wetting of the former compatibilizer in the matrix polymer.

Abstract:The viscoelastic, mechanical and morphological properties of polypropylene/exfoliated graphite nanocomposites with different contents of nanofiller were investigated. According to transmission electron microscopy results, the nanofiller particles were homogeneously dispersed in the matrix. The rheological properties indicated that incorporation of graphite improved the matrix stiffness and had a reinforcing effect. Exfoliated graphite had a weak interaction with the polypropylene. The behavior of the nanocomposites was similar to that of polypropylene in terms of the interfacial detachment inferred from the transmission electron microscopy images and of their G' (storage) and G'' (loss) moduli, and viscosity. The mechanical properties of the nanocomposites compared to the matrix improved significantly for the flexural and storage moduli with little loss of impact strength.

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