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Nanocomposites were processed by melt blending two reference matrices, a metallocene polyethylene and a low density maleic anhydride‐grafted polyethylene with an organo‐modified montmorillonite. It was shown that the introduction of a maleated polyethylene compatibilizer was required to improve the clay nanoplatelet dispersion in the metallocene polyethylene‐based nanocomposites. Increasing the montmorillonite content led to a significant increase of the barrier properties. Interfacial agents such as oxidized paraffins were shown to be more effective to reduce the gas permeability than maleated polyethylene and the dependence of the gas transport properties was discussed not only as a function of the clay dispersion but also as a function of the clay/compatibilizer and compatibilizer/matrix interactions. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 431–440, 2006

Epoxy–amine networks are known to be homogeneous. However, using new analysis tools that allow the observation scale to be reduced to a nanometric level, some authors have stated the opposite. In this work, the network morphology has been studied with atomic force microscopy in the tapping mode as a function of the hardener nature and the stoichiometry of the reactive blend. A very homogeneous epoxy network topography, similar to that of an amorphous thermoplastic, has been obtained. For comparison, a truly heterogeneous network topography, like that of unsaturated thermosets cured by free-radical mechanisms, has been imaged. For the observation of surfaces on a scale smaller than a nanometer, caution must be taken:(1) the tips must be freshly cleaned so that distortion on the image is prevented and (2) the surfaces must be very flat so that the phase contrast is not influenced significantly by differences in the sample topography. This works gives guidelines on using atomic force microscopy in the tapping mode for epoxy–amine network characterization and discusses epoxy–amine network homogeneity. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2422–2432, 2003

IR spectroscopy has been used to follow the transformation at different temperatures of piperidine chemisorbed on oxidic or sulfided Ni−W/Al2O3 catalysts. Formation of an intermediate species, possibly tetrahydropyridine, and pyridine is evidenced. Their formation temperature on the sulfided samples accounts for the catalyst activity in pyridine hydrogenation under H2 pressure.

IR characterization and activity measurements of a sulfided Co-Mo/Al2O3 catalyst (3.6% CoO; 14% MoO3) prepared by thermodecomposition of Co(CO)3NO on a sulfided Mo/Al2O3 sample are compared to those of the conventional Co-Mo/Al2O3 industrial catalyst. The ex-carbonyl preparation leads to a higher degree of promotion for the Co-Mo couple, as evidenced by a two-fold increase in HDS activity and by a more intense signal of adsorbed CO on the promoted sites. On the other hand, the hydrogénation activity is not sensitive to the method of preparation.

The adhesion between glass and polyethylene (high-density polyethylene (HDPE) or low-density polyethylene (LDPE)) was improved by means of polyethylene chains grafted on the glass surface. Chlorosilane-terminated polyethylene (PE) with different molar masses were synthesized in order to obtain (i) semicrystalline polymers able or not to crystallize with the free chains of the polyethylenes matrices and ( ii) polymer chains which could react with the silanol groups from the glass surface. The grafting of alkylchlorosilanes (alkyl chain length varying from C4H9 to C30H61) was considered in comparison to the polymer chains. The adhesion developed at the polyethylene/glass interface was studied as a function of the molar mass of functionalized-polyethylene grafted on the glass surface. For that purpose, the asymmetric double cantilever beam test was used to determine the fracture energy, Gi, of the interface. On both high-density and low-density polyethylene/glass joints, the fracture energy of the interface, Gi, was found to increase with the length of the interfacial connecting chains. The locus of the failure was studied by means of wettability measurements and atomic force microscopy analysis of the surfaces after separation. The higher values of the fracture energy of the interface with HDPE can be explained by a better compatibility of the tethered-PE chains with the free chains of the PE matrix which are more linear than LDPE. It was demonstrated that for the shortest chains (alkylchlorosilanes), the connectors were extracted from the bulk PE (LDPE or HDPE) whereas for the polymeric chains, a cohesive failure occurred for the glass/HDPE interfaces. Such a study can be used to design the connecting polymeric chains for improving the adhesion between glass and a semicrystalline polymer.