New functionalized polypropylenes as controlled architecture compatibilizers for polypropylene layered silicates nanocomposites.

Polypropylene (PP) samples functionalized with Maleic Anhydride (MAH) were used as interfacial coupling agents during the preparation of PP based layered silicate nanocomposites (PP-LSN). To prepare these functionalized PP samples, butyl 3-(2-furyl)propenoate (BFA) was used as coagent during the radical post-functionalization with MAH to avoid the polymer degradation. The obtained materials, differing from the functionalization degree (FD) and structure (MW and molecular weight distribution), were accurately characterized and firstly employed as polymer matrices for PP-LSN preparation to study the influence of their architecture on clay dispersion and thus on their intercalation capability. Successively, PP-LSNs were prepared by using PP as matrix and 5 phr of the above compatibilizers. Morphological, thermal, mechanical and thermo-mechanical analyses of the nanocomposites pointed out that the higher molecular weight PP-g-MAH samples allow to achieve simultaneously a good intercalation within the filler and a significant compatibilization with pristine PP chains, leading to high performances PP-LSNs.

Organophilic Boehmite nanoparticles by ATRP methacrylates polymerization: synthesis, characterization and dispersion in polypropylene.

Boehmite nanoparticles covered with a polymer shell enhancing the organophilicity of the surface were prepared by physical adsorption of a polyelectrolyte atom transfer radical polymerization (ATRP) macroinitiator followed by graft-polymerization of methyl methacrylate or 2-hydroxyethyl methacrylate. The presence of polymer chains adsorbed/grafted on the Boehmite was confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy and by thermo-gravimetric analysis (TGA), which showed a significant amount of polymer covering the particles. The methodology of polymerization and the kinetics suggested the possibility to modulate the amount, type and thickness of grafted polymer shell. These organic-inorganic hybrid materials were melt compounded in a Brabender mixer with isotactic polypropylene in the presence of functionalized polypropylene. The dispersion degree of Boehmite nanoparticles in the polypropylene matrix as well as their reinforcing effect were studied by morphology characterization [scanning electron microscopy (SEM) and X-ray diffraction (XRD)], whereas thermal and thermo-mechanical properties were assessed by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA).