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The use of reactions between polycarbonate (PC) and polystyrene-block-poly(ethylene-butylene)-block-polystyrene- grafted-maleic anhydride (SEBS-g-MAH) is a convenient way to create SEBS-g-PC. Grafting was realized by reactive extrusion at three temperatures using SnOct2 or TBD catalysts. SEC analyses showed the apparition of a double distribution when the TBD was used. The mean residence time widely increased when this catalyst was used, and the rheological curves depicted a percolation effect of the SEBS nodules in the PC matrix. No explicit evolution was found with the use of SnOct2. The thermal analyses showed the disappearance of the PC phase transition temperature. The Van Gurp-Palmen plots confirmed the efficiency of the TBD catalyst and that 260°C was the optimal reactive extrusion temperature. POLYM. ENG. SCI., 54:2660–2668, 2014. © 2013 Society of Plastics Engineers

International audience; Polymer materials with antimicrobial activity are prepared by UV polymerization of acrylate and methacrylate mixture at room temperature. The antimicrobials are silver acetate and copper (II) acetate, used without pretreatment. Their chemical stability in the acrylate matrix and their effect on the thermal and mechanical properties of the polymer matrix are investigated as a function of their concentration up to 15 wt%. Physico-chemical, thermal, rheological, and morphological analyses as well as the surveillance of metal salts release in aqueous medium are conducted. A significant decrease in the thermal stability of the salts introduced into the acrylate matrix is observed after UV treatment. The metal salts also have significant effects on the properties of the matrix. A plasticization and densification of the material associated with an aggregation of salts up to the percolation at the highest concentration are highlighted. At equal concentrations, the effects are more pronounced in the presence of copper salts. The latter was released more slowly than silver salts from acrylate material.

To create reversible supramolecular ionic networks, ionic cross-links were formed from acid pendant functions in poly(styrene-co-methacrylic acid) copolymers by the addition of calcium carbonate. The random dispersion of acid functions in the polystyrene chain is ensured by NMR analysis. The partial reaction of the calcium carbonate with the carboxylic acids is highlighted by a limewater test. The influence of methacrylic acid and calcium-carbonate contents on the formation of an ionic network has been studied through solubility tests. Two main effects were obtained: the exfoliation of the unreacted calcium carbonate characterized by TEM is due to ionic interactions at the surface of nanometric particles that form the first level of organization of the calcium carbonate. Another part of the calcium carbonate reacts with carboxylic acid and is detached from particles to form clusters as shown by x-ray analysis. Finally, by analyzing the dynamic rheological spectrum, the conclusion that the strength of the ionic bonds arises with the calcium content is made. The interest of such an approach with a wide range of observed phenomena in the material is a one-batch process to make thermoreversible nanocomposite networks. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Dynamic covalent reorganization of polycaprolactone (PCL) and poly(ethylene-co-vinyl alcohol) (EVOH) were realized by solvent free transesterification reactions. Organometallic and organic catalysts effect on these reactions was first evaluated from kinetic studies on small molar mass model reactants. Kinetic constants and activation energies of these second order reverse reactions were calculated. At the higher temperatures, side reactions were observed; they were identified as being principally dehydration reactions. Reactions conducted onto polymers were slower than those on model reactions. This was due to the immiscibility of the used polymers resulting in diffusion controlled reactions. Two competitive types of reactions were detected, since at the catalyst addition, fast induced reorganization of PCL leading to low PCL molar mass decreases the mixing torque, followed by grafting reactions of PCL onto EVOH, resulted in an important increase of the mixing torque. Substitution rate of the EVOH hydroxyl groups were measured up to 14% by 1H-NMR spectroscopy. Increasing substitution rate leaded to a decrease of the copolymer crystallinity and the more substituted copolymers were amorphous. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

International audience; Chemical modification of EVOH in the molten state at 185 degrees C by a grafting from process of poly(epsilon-caprolactone) in batch was studied. (1)H NMR was used to characterize the structure evolutions of PCL grafts. In addition to grafting reactions, dynamic covalent transesterification reactions between EVOH residual alcohols and the polyester grafts led to a redistribution of the PCL grafts length. (Dp) over bar (n) up to 27 and SR up to 80% were obtained. Experiments made in a corotating mini twin-screw extruder also confirmed these results. The effect of the alcohol to caprolactone ratio and catalyst concentration (SnOct(2)) on kinetic evolution showed that few minutes were necessary to complete the polymerization. A kinetic model was proposed and adequate conditions for the synthesis by reactive extrusion were defined.

International audience; EVOH-g-PCL were prepared by a solvent-free reactive extrusion process using a co-rotating twin screw extruder. Kinetic simulations were made of selected reaction conditions at 185 degrees C. Changes in the screw rotation rate resulted in evolution of the residence time distribution and slightly changed the monomer conversion. An increase of the [OH](0)/[Cl](0) ratio made the reactive system more viscous and decreased the overall pumping capacities of the extruder. Increase of the mean residence time, combined with a positive kinetic effect of [OH](0) increase, leaded to an important increase in conversion. For all the conducted experiments, equivalent distribution dispersions and good agreements between calculated conversion and those measured were obtained. An increase in temperature from 185 to 200 degrees C resulted in total conversion.

The diffusion study of a carbonate mixture composed of ethylene and propylene carbonates in poly(vinyl alcohol-co-vinyl acetate) (PVA–Ac) was studied. The diffusion occurred in the solid state and the effect of the carbonate mixture on the PVA–Ac properties are presented as well as the homogeneity of the diffusion. Due to the complexity of the diffusion kinetics with temperature, a model was made using the free volume theory at 75 °C. This temperature was chosen for modelling because the physical properties of the polymer are relatively stable at this point. Swelling heterogeneity, due to the particle size distribution of the powder, were estimated. Copyright © 2004 Society of Chemical Industry