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In this study, a polyethylene grade used for applications in the insulation of energy cables was crosslinked by the peroxide crosslinking route. The impact of dicumyl peroxide (DCP) crosslinking on the polymer microstructure was studied. The different byproducts formed during the crosslinking reaction [acetophenone, α-cumyl alcohol, and α-methyl styrene (aMS)] were identified and quantified. Another molecule, 2,4-diphenyl-4-methyl-1-pentene, regarded as an aMS dimer, was detected for the first time. Some amounts of residual DCP were also detected. A detailed study of the diffusion mechanism of each byproduct under different desorption conditions (e.g., samples exposed to vacuum or atmospheric conditions) and temperatures was performed. The diffusion coefficient values were determined and are discussed as a function of the desorption conditions and byproduct characteristics. Through this study, essential diffusion parameters were provided as a first step for further modeling development to allow the definition of optimized desorption conditions for a large range of sample geometries and thicknesses. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44525.

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.

Polylactic acid was bioconjugated with glutathione (GSH) in a solvent-free one step process. Thermo-reversible networks were first obtained as a consequence of the supramolecular interactions induced by GSH moieties. Then dynamic covalent reactions were added to the networks' synthesis process using dialcohol-functionalized Diels−Alder (DA) adducts. The main properties of these networks were analyzed in relation with their structures and the proportions of supramolecular and DA reactions. The thermo-mechanical properties of the obtained transparent materials and their healing efficiency were evaluated by dynamic mechanical spectroscopy and tensile analyses. Crosslinking/de-crosslinking temperatures varied from 36 to 112°C. The obtained networks showed self-healing ability without external stimuli. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43436.

Poly(e-caprolactone) (PCL)-based thermoreversible networks with self-healing properties were prepared through Diels- Alder (DA) and retro-DA reactions. Bis- or Tris-maleimide compounds and a series of copolymer(caprolactone-diene) PCLXFY (X: degree of polymerization and Y: furan-average functionality) with Y between 2.4 and 4.9 were used. The successive sequences of for- mation and dissociation of polycaprolactone networks via DA and retro-DA reactions were observed repeatedly by dynamic mechani- cal analyses (DMA) and their gel-temperatures determined. The cross-linking densities, thermal properties, and thermal reversibility of the PCLXFY/multimaleimide polymers have been modulated by the structure and functionalities of the used diene and dienophile moieties. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 000: 000-000, 2012

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

International audience; Monodisperse styrene/methyl methacrylate/acrylic acid (St/MMA/AA) copolymer microspheres have been prepared with surfactant-free emulsion polymerization in air. The presence of oxygen in the system not only caused an induction period but also decreased the average particle size (D(p)). However increasing AA concentration ([AA]) gave a reduction in the induction period. The FTIR and NMR analysis of the latex copolymer confirmed that the correlation of the copolymer compositions with the feed compositions was much better at the lower [AA] than at the higher levels. The AA contents of the copolymers obtained in air were much lower than those of the copolymers obtained under N(2) protection. Decreasing [AA] led to decrease in the copolymer molecular weight and broadening of the molecular weight distribution, but the particle size distribution (delta/D(p)) was unaffected. In addition, the average particle diameter (D(p)) was proportional to [AA](-0-2.55), and increasing comonomers feed content caused linear increase of D(p), and a monodisperse sample with final solids contents up to 34.2 wt % was obtained.

Poly(n-butyl methacrylate) (PBMA) composites with calcium carbonate (CaCO3) were prepared by in situ radical copolymerization of butyl methacrylate (BMA) and methacrylic acid (MA) with precipitated calcium carbonate. To compare the different rheological behaviors of the monomer mixtures with CaCO3 and the composites, the steady and dynamic viscosities of BMA/MA/CaCO3 and poly(BMA/MA/CaCO3) were measured by means of steady and oscillatory shear flows. The viscosity of the mixture BMA/MA/CaCO3 was found to increase evidently with the increasing of CaCO3%. The influence of MA% on viscosity of BMA/MA/CaCO3 was slight. During the in situ polymerization, the viscosity of the reacting system was measured to be enhanced by a factor of about 104 from the monomer/CaCO3 mixture to composites. The dependency of zero-shear viscosity on molar mass of PBMA was also investigated. The relation between the zero-shear viscosity and molar mass is η0 = 10−15Mw3.5. The evolution of the viscosity with the temperature for both PBMA and its composites was obtained and time–temperature superposition was used to build master curves for the dynamic moduli. The flow activation energies were found to be 115.0, 148.6, and 178.7 kJ/mol for PBMA, composite PBMA/CaCO3 (90/10), and PBMA/MA/CaCO3 (89/1/10), respectively. The viscosity of the composites containing less than 10% CaCO3 was lower than that of pure PBMA with the same molar mass. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1376–1383, 2003

Poly(ethylene terephthalate) (PET) was melt-blended at 270°C with two epoxy monomers, diglycidyl ether of bisphenol A (DGEBA) and 3,4-epoxycyclohexyl-methyl-3,4-epoxycyclohexyl carboxylate (ECY). Intermediate proportions of the epoxy in the range of 20–0.5 wt % were used. If the epoxy monomers were added in a high proportion (10–20%), a large fraction did not react with PET. Calorimetric experiments showed that the unreacted fractions of both epoxies were miscible with the amorphous phase of the polyester. Only one glass-transition temperature was detected. It was depressed as the epoxy content was increased. The transition was broad when the PET component was crystalline, and it was narrow when the PET component was made amorphous by quenching of the blend. These features were confirmed by dynamic thermal mechanical analysis. As is often the case for crystalline blends, the crystallization and melting temperatures decreased when the proportion of the epoxy was increased. Concerning the reactivity of the epoxy with PET, the behavior differed according to the nature of the epoxy. The DGEBA monomer showed a low reactivity. It was not effective for the chain extension of PET, and no increase in the intrinsic viscosity was observed under the experimental conditions. However, some functionalization of the chain ends may be possible at a high concentration of the epoxy. ECY was more reactive, and the molecular weight of the processed PET increased, although the value of the commercial untreated polyester was not attained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1995–2003, 2003

PCL-segmented multiallyl-functionalized poly (ester urethane) prepolymers (PEUs) were prepared in a two-step process. First, hydroxyl-terminated PCL and glycerol simultaneously reacted with an excess of a diisocyanate, the obtained isocyanate functionalized prepolymers then reacts with allyl amine. PEUs structure choice mainly focused on two aspects: the PCL segments concentration and the allyl functionality that, respectively, affects the biodegradability and the density of the issued networks. The concentrations of the different reactants were fixed, taking into account the desired mean structure and also to prevent crosslinking during the synthesis of the prepolymers. FTIR was principally used to monitor the synthesis of allyl functionalized PEUs. The carbonyl absorption of PCL, initially located at 1720 cm−1, reaction of the PCL and shifted toward 1730 cm−1, due to a decrease in crystallinity as confirmed by DSC. The structure of allyl-functionalized PCL-segmented PEU analyzed by 1H NMR, double bond content was between 0.2 and 1.2 mmol g−1. Networks were obtained by UV-initiated radical copolymerization of allyl-functionalized PEUs and HEMA. The effects of PCL concentration and molar mass on their thermomechanical and thermal properties were analyzed. Particular damping properties were obtained. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41295.

A rheological method to assess the diffusion behavior of liquids in molten polymers above their boiling point is presented in this article. The evaporation of the liquid and the evolution of the blends complex modulus are followed by rheological measurement. Identification of the Fick's diffusion coefficient and the rate of evaporation of butylmethacrylate in low density polyethylene is done. The values of the diffusion coefficient are in agreement with those obtained by classical methods. The method developed here appears as complementary to the existent ones. It allows the measurement of diffusion coefficient of liquid/polymer system at high temperatures even for volatiles liquids. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010