Barhoumi N.,CNRS Laboratory for Polymer Materials Engineering |
Maazouz A.,CNRS Laboratory for Polymer Materials Engineering |
Jaziri M.,University of Sfax |
Abdelhedi R.,University of Sfax
Express Polymer Letters | Year: 2013
A reactive rotational molding (RRM) process was developed to obtain a PA6 by activated anionic ring-opening polymerization of epsilon-caprolactam (APA6). Sodium caprolactamate (C10) and caprolactam magnesium bromide (C1) were employed as catalysts, and difunctional hexamethylene-1,6-dicarbamoylcaprolactam (C20) was used as an activator. The kinetics of the anionic polymerization of ε-caprolactam into polyamide 6 was monitored through dynamic rheology and differential scanning calorimetry measurements. The effect of the processing parameters, such as the polymerization temperature, different catalyst/activator combinations and concentrations, on the kinetics of polymerization is discussed. A temperature of 150°C was demonstrated to be the most appropriate. It was also found that crystallization may occur during PA6 polymerization and that the combination C1/C20 was well suited as it permitted a suitable induction time. Isoviscosity curves were drawn in order to determine the available processing window for RRM. The properties of the obtained APA6 were compared with those of a conventionally rotomolded PA6. Results pointed at lower cycle times and increased tensile properties at weak deformation. © BME-PT.
Zhang X.,CNRS Laboratory of Chemistry, Catalysis, Polymers and Process |
Boisson F.,CNRS Laboratory for Polymer Materials Engineering |
Colombani O.,University of Maine, France |
Chassenieux C.,University of Maine, France |
Charleux B.,CNRS Laboratory of Chemistry, Catalysis, Polymers and Process
Macromolecules | Year: 2014
The batch copolymerization of n-butyl acrylate (50 mol %) and acrylic acid (50 mol %) - two monomers with close reactivity but with very different water solubility - was performed under RAFT (reversible addition-fragmentation chain transfer) control, in heterogeneous conditions in water or water/ethanol mixtures. The polymerizations were conducted in the presence of poly(acrylic acid) end-capped with a trithiocarbonate reactive group, serving as a control agent, a precursor for the in situ synthesis of amphiphilic block copolymers and a stabilizer for the formed particles. Good control over the polymerization and stable colloidal suspensions were achieved under such conditions. The kinetic study demonstrated that the polymerization rates of each monomer varied upon a change of the water/ethanol volumetric ratios and of the overall comonomer concentrations. The compositional microstructure of the copolymers was characterized by NMR analysis and by potentiometric titration. This work demonstrates that the distribution of the comonomer units in a copolymer formed under heterogeneous conditions can be controlled by the solubility of the monomers in the medium, hence leading to various types of compositional gradient structures. © 2013 American Chemical Society.
Bendaoud A.,Jean Monnet University |
Bendaoud A.,CNRS Laboratory for Polymer Materials Engineering |
Chalamet Y.,Jean Monnet University |
Chalamet Y.,CNRS Laboratory for Polymer Materials Engineering
Carbohydrate Polymers | Year: 2013
The purpose of the present work was to investigate the relationship between the glass transition temperature of the materials produced by the melting method and the water content, as well as the nature and concentration of the plasticizer used. Native starch was successfully treated with ionic liquid to obtain thermoplastic starch (TPS). Ionic liquids have shown a better plasticization, and low absorption of water compared to glycerol, which means a better interaction of starch with ionic liquids. The water binding properties of TPS were studied by commenting the water absorption for the plasticized starch at different % RH and with different ratios of plasticizers. An amount of 22.5 wt% AMIMCl is the maximum that can act as a plasticizer. Above this composition, an increase in the wt% water and wt% AMIMCl induces a phase separation. This value corresponds to a chemical interpretation, which corresponds to a ratio of 1:3 AMIMCl/anhydro-glucose. A schematic representation of the different binding between starch, plasticizer and water has been proposed. © 2013 Elsevier Ltd. All rights reserved.
Taguet A.,Ecole des Mines d'Ales |
Cassagnau P.,CNRS Laboratory for Polymer Materials Engineering |
Lopez-Cuesta J.-M.,Ecole des Mines d'Ales
Progress in Polymer Science | Year: 2014
Hybrid ternary blends comprising two polymers and one mineral (nano)filler are increasingly studied because they are starting to be widely used to respond to industrial issues. The objective of this review is to gather information on these particular systems. Concerning first thermodynamic effects of fillers on the phase separation of an immiscible polymer blend, Flory-Huggins theory demonstrate stabilization. This theory was particularly taken up and developed for the case of two polymers and one filler by Lipatov and Nesterov in the 90s. More recently, Ginzburg generalized this theory to the case of unfavorable enthalpic interactions between a particle and the two polymers. They showed that the amount of particles had to attain a certain threshold to stabilize the system and the lower the particle radius, the higher the stable zone area. Generally speaking, all the phenomena regarding the morphology of polymer blends are governed by thermodynamics and/or kinetic effects, as well as the localization of nanoparticles. The main discussed thermodynamically controlling parameter of the localization is the wetting parameter ωAB. However, because of the viscosity of the system, the equilibrium dictated by ωABmay never be reached. Hence, concerning the kinetic effects, the final localization of fillers in a polymer pair is guided by the sequence of mixing of the components, the viscosity ratio, the composition, the temperature, the shear rate and the time of mixing. When the particles are placed at the interface between two polymers, coalescence can be suppressed or/and interfacial tension can be reduced. In that case, particles are known to play the role of a compatibilizer. In a ternary system, (i) the shape of the particle (spheres, rods or "onions-shape"), (ii) the particle radius (Rp) versus the radius of gyration of the polymers (Rg) and (iii) the surface chemistry of the particles affect the final localization of the particles (thus, the compatibilizing effect) and the final properties of the material, such as mechanical, conductive, magnetic and thermal properties. This review details recent works for which those four above mentioned properties are improved by incorporating different kind of fillers in polymer blends. © 2014 Elsevier Ltd.
Lamnawar K.,University of Lyon |
Bousmina M.,Hassan II Academy of Science and Technology |
Maazouz A.,University of Lyon |
Maazouz A.,Hassan II Academy of Science and Technology |
Maazouz A.,CNRS Laboratory for Polymer Materials Engineering
Macromolecules | Year: 2012
The aim of the present work has been to gain a fundamental understanding of the mechanisms governing encapsulation in the multiphase systems as a blend or multilayer structures. The model systems chosen for this study are based on (i) Newtonian poly(dimethylsiloxane) polymers of varying molar masses and (ii) high molecular weight, viscoelastic, and compatible pair polymers of PVDF and PMMA. The same approach was applied to functionalized polymers to investigate the effect of physicochemical affinity on two pairs of asymmetrical reactive polymers based on PE-GMA (glycidyl methacrylate)/PVDF-g-MA (maleic anhydride) and a PE/PVDF as a reference. The linear viscoelastic and surface properties of the neat and bilayer model systems structures have been investigated. The optical obeservations of the encapsulation kinetic of two drops were recorded using a homemade device. Specific experiments were carried out to follow up the kinetic of encapsulation, and the results were rationalized as a function of the effect of the viscosity, elasticity ratios, drop geometry, the interfacial tension, and the physicochemical affinity. Throughout all the experiment, the mechanisms were purposed for each system and discussed based on the theories of molecular forces or Brownian motion governing diffusion and Ostwald ripening, in contrast to the theories of coalescence. The viscosity ratio coupled to the drop geometry of the material was found to be a key parameter and that it has to be linked to the interfacial tension and spreading parameters. Furthermore, the encapsulation appeared to be hindered by the interdiffusion process in the case of compatible pair system despite their elasticity and surface tension contrast. Finally, the encapsulation kinetic could be reduced or eliminated by the creation of a copolymer at the interface for a reactive system. The results obtained by the optical investigation of two drops corroborated the rheological data of the bilayer systems. Hence, the obtained results rendered it possible to decouple the influence of the viscoelastic parameters to flow, interfacial tension, thereby highlighting a number of macroscopic effects that were governed by the interdiffusion or reaction of macromolecular chains at the interface to give a better understanding of encapsulation phenomenon in multiphase systems. © 2011 American Chemical Society.
Serghei A.,CNRS Laboratory for Polymer Materials Engineering |
Zhao W.,University of Massachusetts Amherst |
Miranda D.,University of Massachusetts Amherst |
Russell T.P.,University of Massachusetts Amherst
Nano Letters | Year: 2013
Polymer systems having one, two, or three dimensions on the nanometer length scale can exhibit physical properties different from the bulk. The degree of disorder characteristic for large amounts of matter is strongly reduced and changes in symmetry are imposed by means of geometrical confinement. This could be used to induce - through orientation and order - enhancement in the material properties. Experiments on extremely small amounts of matter, however, are naturally characterized by large fluctuations in the measured signals, especially in the case of polymer objects having three dimensions on the nanometer length scale. This imposes the necessity of repeating the measurements until a statistical distribution is obtained. Here we show that investigations on statistical ensembles of attograms of material (1 ag = 10-18 g) are possible in a single experiment by employing highly ordered arrays of identical, independent, additive nanocontainers. Phase transitions corresponding to attograms of a ferroelectric polymer are measured by this approach. As compared to one- or two-dimensional confinement, significant changes in the Curie transitions are found. © 2013 American Chemical Society.
Benaniba M.T.,Ferhat Abbas University Setif |
Massardier-Nageotte V.,CNRS Laboratory for Polymer Materials Engineering
Journal of Applied Polymer Science | Year: 2010
Sunflower oil (SO) is a renewable resource that can be epoxidized, and the epoxidized SO has potential uses as an environmentally friendly in polymeric formulations, especially for poly (vinyl chloride) (PVC). Epoxidized sunflower oil (ESO) was prepared by treating the oil with peracetic acid generated in situ by reacting glacial acetic acid with hydrogen peroxide. Epoxidation was confirmed using spectroscopic and titration methods. ESO was used as a coplasticizer in PVC for the partial replacement of di-(2-ethyl hexyl) phthalate (DEHP). The effect of ESO on the thermal stability of plasticized PVC was evaluated by using synmero scale for the sheets. In presence of ESO plasticized PVC samples showed a reduction in discoloration and the number of conjugated double bonds. By using thermogravimetry, the incorporation of 15/45 of ESO/DEHP in PVC presents the lowest weight loss. The results of the shore hardness and mechanical properties showed that a proportion of DEHP could be substituted by ESO. By use of DMA, the formulation which contains 25 % wt of ESO in plasticizer system shifts the glass transition temperature (Tg) to ambient temperature. The migration phenomenon was studied on PVC based samples plasticized with DEHP and ESO in varying amounts. The migration was monitored by the weight loss percentage of the samples immersed into nhexane or heated in an oven. The amount of extracted or volatilized DEHP is proportional to the added ratio of ESO in plasticizer system. All of this favored the partial replacement of DEHP by ESO as biobased plasticizer for flexible PVC. © 2010 Wiley Periodicals, Inc.
Obadia M.M.,CNRS Laboratory for Polymer Materials Engineering |
Drockenmuller E.,CNRS Laboratory for Polymer Materials Engineering
Chemical Communications | Year: 2016
Poly(ionic liquid)s (PILs) are a unique class of polyelectrolytes having properties suited for modern technological applications such as electrochemical devices (batteries, supercapacitors, light-emitting electrochemical cells), ion-gated field effect transistors, electrochromic devices, fuel cells, dye sensitized solar cells, catalysis, or soft robotics. Their structure and properties can be finely tuned by unlimited combinations issued from extended pools of cationic and anionic building blocks. In a constant quest for the development of solid polymer electrolytes with enhanced physical, mechanical and (electro)chemical properties, a new class of PILs based on 1,2,3-triazolium cations has been recently developed. Their preparation takes advantage of the beneficial features of the multiple combinations between the Click chemistry philosophy with macromolecular engineering techniques to afford tunable and highly functional ion conducting materials thus stretching out the actual boundaries of PILs macromolecular design. This feature article summarizes the different strategies developed so far for the synthesis of 1,2,3-triazolium-based PILs (TPILs) since their first introduction in 2013. © 2016 The Royal Society of Chemistry.
Jouni M.,CNRS Laboratory for Polymer Materials Engineering |
Boiteux G.,CNRS Laboratory for Polymer Materials Engineering |
Massardier V.,CNRS Laboratory for Polymer Materials Engineering
Polymers for Advanced Technologies | Year: 2013
The present work focuses on the study of the electrical properties of high-density polyethylene (HDPE)/multiwalled carbon nanotube (MWCNT) nanocomposites. The samples were produced by melt mixing by diluting a masterbatch of HDPE/MWCNT using two types of mini-extruders in order to see the influence of the shear processing on the electrical properties. The dielectric relaxation spectroscopy was used for the investigation of the electrical properties in the studied samples. The composites dc conductivity (σdc) follows the scaling low derivate from the percolation theory of the form σdc~(p-pc)t. A low electrical percolation (pc≈0.3-0.4vol.%) was found in both cases. The critical exponent t had a value very close to the theoretical one for a percolation network in three dimensions (t≈2). The analysis of the morphology of the nanocomposites showed a good and homogeneous dispersion of the fillers in the PE matrix. The effect of the incorporation of MWCNTs on the dynamic mechanical and thermal behaviors was also presented. The MWCNTs have improved the mechanical properties of the polyethylene matrix and increased the crystallization temperatures. © 2013 John Wiley & Sons, Ltd.
Polexe R.C.,Cytosial Biomedic |
Delair T.,CNRS Laboratory for Polymer Materials Engineering
Molecules | Year: 2013
In this study, we describe the elaboration of multifunctional positively charged polyelectrolyte complex (PEC) nanoparticles, designed to be stable at physiological salt concentration and pH, for effective targeted delivery. These nanoparticles were obtained by charge neutralization between chitosan (CS) as polycation and hyaluronic acid (HA) as polyanion. We showed that the course of the complexation process and the physico-chemical properties of the resulting colloids were impacted by (i) internal parameters such as the Degree of Acetylation (DA, i.e., the molar ration of acetyl glucosamine residues) and molar mass of CS, the HA molar mass and (ii) external parameters like the charge mixing ratio and the polymer concentrations. As a result, nonstoichiometric colloidal PECs were obtained in water or PBS (pH 7.4) and remained stable over one month. The polymer interactions were characterized by thermal analysis (DSC and TGA) and the morphology was studied by scanning electron microscopy. A model antibody, anti-ovalbumine (OVA) immunoglobulin A (IgA) was sorbed on the particle surface in water and PBS quantitatively in 4 h. The CS-HA/IgA nanoparticles average size was between 425-665 nm with a positive zeta potential. These results pointed out that CS-HA can be effective carriers for use in targeted drug delivery. © 2013 by the authors.