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International audience; There is a need to find alternatives to the extraction of non-renewable mineral resources for the production of new binders. Some specific building materials such as plant-aggregate-based concretes do not require high-strength binders. In this context, the lime-pozzolan technology, inherited from Roman times, can help reduce the carbon footprint of finished materials by the use of low amounts of lime. In this paper, three different marine dredged sediments were used as natural alumino-silicate resources and blended with hydrated lime. Based on previous literature dealing with the pozzolanic activity of cristallized minerals, the sediments were reduced to micronized powders. The hydration of these systems was investigated through hardening and reaction kinetics up to 365 days at 20 °C and 50 °C. The sediments used revealed two kinds of mineral assemblages and the best pozzolanic reactivity was found with quartz-rich sediments. In addition, the optimum lime content was found to be 20 wt% until 180 days

Currently, there is a great demand for functional materials with effective pathogen-killing properties. In this research, we describe the use of green technology “reactive extrusion” for the synthesis of potent antimicrobial materials based on Ethylene-vinyl alcohol copolymer (EVOH). Herein, the antimicrobial agent, copper (II) acetate was used without pretreatment and introduced into the EVOH matrices at high temperatures. The thermal reaction of copper (II) acetate within the EVOH matrices and their effect on the thermal and thermomechanical properties of the polymer were investigated in regards to their concentration. The physicochemical, thermal, and rheological features, as well as, metal salt release kinetics were reported. The antimicrobial agent had significant effects on the properties of the matrix. Results showed a reduction in the glass transition temperatures and storage modulus of the materials in response to the incorporation of copper (II) acetate. Finally, the antimicrobial activity of the products was studied and demonstrated a possibility to create antimicrobial materials in a one-step, solvent-free extrusion process.

Environmental and ecological issues have led to the development of new sustainable channels for the recovery of dredged sediments. One of the major difficulties of sediment valorization lies in particular in its very heterogeneous composition. For example, the presences of heavy metals and organic matter have a significant influence on the environmental impact of materials formulated with sediment. Some heavy metals such as antimony, mercury, lead, and cadmium in high concentrations are dangerous to the body. Trace metals trapped in sediments are transformed through complex biogeochemical processes. They subsequently associate with organic matter to form clay-humic groups that define the degree of sediment pollution. The Harbour Dredging Sediments (HDSs) used were classified as non-hazardous waste in accordance with Directive 12/12/14/EC. The purpose of this study is to evaluate the environmental impact of the use of HDS from active lagoon in the formulation of self-compacting concrete (SCC) with the objective of incorporating a high sediment content, obtaining materials with a low environmental impact and ensuring compressive strength of a C25/30 class concrete. Three HDSs are being studied that have a significant impact their difference by their fines content at 125 μm. Sediments recovered from the active lagooning process have not undergone any physical, chemical, or thermal treatment. The DMDA (Densified Mixture Design Algorithm) method is used to optimize the composition of "sediment" SSCs. The communication focuses on mortars equivalent to these "sediment" SCCs (SCMs). Sediment represents about 20% of the granular composition with a sediment-to-cement ratio of 80%. Compressive strengths are greater than 25 MPa and tensile strengths are in the range of 3 to 8 MPa at 28 days of curing. From an environmental point of view, all heavy metals are stabilized except nickel. In particular, there has been a considerable decrease in the levels of sulfate, total organic carbon, and chloride. The different SCMs are classified as inert, clinker hydration produces hydrates that capture and stabilize heavy metals in the cementitious matrix. The results obtained show that HDSs could be used as a secondary raw material in the formulation of self-compacting concretes.

Municipal solid waste incineration generates large quantities of bottom ash that should be recycled. Current use of municipal solid waste incineration bottom ash (MSWI-BA) in cementitious materials is mostly in Ordinary Portland Cement (OPC). This paper considers using MSWI-BA as sand substitution in Calcium Sulfoaluminate Cement (CSA) as an alternative to OPC. A comparison between OPC and CSA mortars containing 0–2 mm MSWI-BA is conducted. The MSWI-BA used was treated to remove the ferrous and non-ferrous metals in order to obtain a better mineral fraction. Different percentages (0%, 25%, 50%, 75%, and 100%) of standard sand were substituted by MSWI-BA based on equivalent volume. Experimental results showed that the compressive strength and porosity of the CSA mortars were superior to OPC after substitution at 1, 7, 28, and 90 days. The compressive strength of OPC mortars with 25% substitution decreased by 40% compared to 11% for CSA mortars at 90 days. This is due to the difference in pH between the two cement pastes as OPC in contact with the MSWI-BA leads to a reaction with the aluminum content which releases hydrogen gas, increases the porosity, and decreases the compressive strength. © The Author(s) 2020.

In this work, poly(trimethylene carbonate) (PTMC)-based multiarm supramolecular polymers bearing self-complementary triuret and tetrauret hydrogen-bonding motifs (HBMs) at the chain ends were synth...

The last several decades have witnessed notable research in natural and biodegradable polymers for applications that interact with humans or the environment. This research describes the synthesis and characterization of temperature sensitive hemicellulose-based gels. Xylan type hemicellulose was converted into a thermoplastic material via the grafting of short polycaprolactone tails to enhance the material processability. The thermoplastic xylan (xylan-grafted-poly(caprolactone) was functionalized with different amounts of furan rings and allowed to react with bismaleimide through Diels–Alder reaction. The temperature dependent bonding/debonding of the designed networks was evaluated by solubility and rheological assessments. The results indicated that the temperature at which the networks disassemble varies based on the amount of the furan moieties in the initial copolymer and can range between 108.6 and 127.6 °C. The designed networks display promising molecular and synthetic features for the production...

International audience; The combination of lime with natural pozzolans for the production of binders in masonry construction dates back to ancient times. These were largely ignored with the industrialization of the building sector even though their use for specific applications is of interest. The use of lime-pozzolan binders with the least amount of lime is a relevant opportunity to reduce carbon emissions due to the decarbonation of limestone for the production of quicklime but also to introduce new alumino-silicate materials. In this context, the present investigation intends to relate marine dredged sediment to pyroclastic materials and to mix it with hydrated lime without any thermal treatment but after micronization. The blends were moist cured either at 20 °C or 50 °C and the paper will discuss the pozzolanic reactivity through the study of compressive strength and reaction kinetics from 3 days to 180 days. Reaction product assemblage, microstructure, and porosity refinement were also addressed after advanced curing ages. Results have well illustrated the long-term pozzolanic reactivity of the marine sediment cured at 50 °C through the whole combination of initially available lime after 60 days and the compressive strength development providing 12 MPa after 180 days.

In this work, thermoreversible poly(trimethylene carbonate) (PTMC) based networks with different crosslinking densities were obtained by Diels–Alder (DA) reaction between furan-functionalized PTMC precursors and a bismaleimide. Furan-grafted PTMC with various functionalities determined by 1H-NMR analyses were prepared from telechelic PTMC oligomer, glycerol, 4,4′-methylenebis(cyclohexyl isocyanate) (H12MDI) and furfuryl alcohol. The formation of network structures by DA reaction between furan and maleimide groups were proved by Fourier-transform infrared spectroscopy (FT-IR). Although both exo and endo DA adduct forms exist, the thermally more stable exo form dominates. The thermoreversibility of networks was evidenced by FT-IR, solubility, differential scanning calorimetry (DSC) and rheology experiments at different temperatures. By increasing furan functionality or node concentration, denser and stiffer networks could be formed with higher Young's modulus and true stress at break in tensile tests, as well as higher crossover temperature, which indicates a nominal transition from elastic behavior to viscous state. The disruption of networks was found to occur in high temperature ranges from 130 to 160 °C, depending on their crosslinking density.

International audience; Currently, there is very strong interest to replace synthetic polymers with biological macromolecules of natural source for applications that interact with humans or the environment. This research describes the development of drug delivery hydrogels from natural polymers, starch, lignin and hemicelluloses by means of reactive extrusion. The hydrogels show a strong swelling ability dependent on pH which may be used to control diffusion rates of water and small molecules in and out of the gel. Also the hydrogels degradation rates were studied in a physiological solution (pH 7.4) for 15 days. The results indicated that for all three macromolecules, lower molecular weight and higher level of plasticizer both increase the rate of weight loss of the hydrogels. The degradation was extremely reduced when the polymers were extruded in the presence of a catalyst. Finally the dynamic mechanical analysis revealed that the degradation of the hydrogels induce a significant reduction in the compressive modulus. This study demonstrates the characteristics and potential of natural polymers as a drug release system.

International audience; Hemicellulose materials are arguably the second most abundant renewable component of lignocellulosic biomass after cellulose. They are relatively under-utilized hetero-polysaccharides present in lignocellulosic biomass. In this research an alkaline treatment was optimized for extraction of polymeric hemicellulose from fully bleached hardwood pulp (B-HWP) and partially delignified switchgrass (SWG). The hemicellulose extracted from B-HWP was relatively pure with zero percent lignin and 89.5% xylose content whereas the partially delignified SWG hemicellulose contained about 6-3% lignin and 72–82% xylose, depending on the NaOH concentration during extraction (3–17% NaOH solution). A maximum molecular weight of SWG hemicellulose of 64,300 g/mol was achieved for the 10% NaOH solution extraction, whereas the MW of B-HWP hemicellulose at 10% NaOH solution extraction was lower at 49,200 g/mol. We have demonstrated that the residual lignin in SWG hemicellulose lowered the system Tg and this might be utilized as a way to increase the applications of hemicellulose in high value biomaterials. Furthermore, the hemicellulose could be crosslinked with zirconium to develop a water resistant gel for coating or adhesive applications. Our results showed that the loading stress required to break an hemicellulose based adhesive connection between two paper surfaces was 0.89, 2.02, 2.75, 3.46, and 3.11 (MPa) for 2, 4, 6, 8 and 10% AZC samples, indicating that up to about 8% AZC crosslinker in the hemicellulose increases the adhesive behavior of the material.

This paper aims at studying the shear behavior of mixtures of fine and coarse particles by classical triaxial tests. The work is performed both on experimental tests and computer simulations by discrete element method. The comparisons between experimental and simulation results on monosized and binary samples show that the DEM model can reproduce deviatoric curves satisfactorily in experimental conditions. The shear behavior of monosized and binary systems with the same initial void ratio differs significantly, suggesting that the state of compaction of the system is more influential than the initial void ratio. Comparison between compacted and uncompacted samples confirms that compaction increases the shear strength of granular matter. At the particle scale, the coordination number decreases with the augmentation of the volume fraction of coarse particles. The average rotation velocity of fine particles is higher than coarse particles, but their particle stress tensor is smaller than coarse ones. © 2017 The Society of Powder Technology Japan

International audience; Lime and hemp concretes are used as infill materials manually tamped in timber stud walls or more recently in the form of precast blocks. In either case, the structural design practice of wood frame construction associated with hemp concrete does not assume any contribution of the plant-based concrete whereas it may contribute towards the racking strength of the wall. This work is intended to evaluate the shear behaviour of two different bio-based concretes by means of triaxial compression. Hemp shives and whole rice husks were mixed with a lime-based binder according to the same mix proportioning and mixes were vibro-compacted in cylindrical forms. Then, samples were cured at 23 degrees C - 65%RH before being tested under unconfined and triaxial compression. The triaxial shear test was performed after 60 days of curing on unsaturated specimens under drained conditions at air pressure and for increasing effective confining pressure (from 25 to 150 kPa). It was possible to estimate the shear strength parameters (peak friction angle and cohesion) of the two plant-based concretes. Comparing results, it appears a consistent value of cohesion but a different friction angle related to the binder and the aggregate contributions respectively. This leads to a first analysis of the relationship between the composition of the concrete (plant aggregates cemented with a binder) and its shear strength. Furthermore, the ductility of plant-based concretes is markedly enhanced as the mean effective pressure increases. Finally, the shear strength of plant-based concretes should be considered as part of the design practice of building envelopes.

This paper aims at studying the shear behavior of homogeneous granular materials by conventional triaxial test. The work is performed both in laboratory tests and by discrete element method simulations. Conventional triaxial tests are performed on glass beads packing, while a cylindrical rigid wall boundary condition based on lame formula and a series of procedures are proposed to simulate the conventional triaxial test. The experimental results on dry and saturated glass beads samples have been studied to find out the effect of saturation condition on the shear behavior. The comparisons between experimental and numerical results show that the numerical model can reproduce deviatoric curves satisfactorily in experimental conditions as long as experimental sample remains cylindrical. It correctly describes the volumetric strains of a numerical sample up to the peak value. Additionally, a parametric study on the influence of main micromechanical parameters has been carried out, which has been compared to experimental tests with glass beads of different textures. The comparison highlights the significant effect of friction coefficients and rolling resistance coefficients on global behavior of granular materials. © 2016 The Society of Powder Technology Japan

The deinking paper sludge (DPS) generated by paper recycling incorporated in ceramic pastes has received significant attention to develop environmentally-friendly construction materials with a good thermal and sound insulation characteristic while maintaining a resistance mechanical acceptable by standards. The environmental risks associated with the incorporation of these sludge into clay bricks that rich in heavy metals such as Cr, Pb, Zn, Cu, Ni, etc. have been evaluated. The evaluation of these metals was carried out by performing the leaching test in order to be able to introduce this new material in the list of materials to be marketed in the field of civil engineering. Leaching tests were performed on clay, DPS and the finished product as fired bricks. Leaching results on clays show that they are non-hazardous products, while heavy metal leaching of DPS is above the limiting concentrations, which classifies DPS as a hazardous waste. In contrast, the leaching concentrations of the bricks incorporated by DPS, show that the heavy metals were immobilized in the ceramic structures of all the fired bricks. In this study, the percentages of DPS added in the composition of the bricks are 8%, 10% and 12%. Results of leaching test suggest that replacing up to 12% of clays with DPS can provide bricks to reduce the environmental impact of abundant waste and preserve non-renewable natural resources.

Stem-cell-based therapy is a promising approach for the treatment of a myriad of diseases and injuries. However, the low rate of cell survival and the uncontrolled differentiation of the injected stem cells currently remain key challenges in advancing stem cell therapeutics. Hydrogels are biomaterials that are potentially highly effective candidates for scaffold systems for stem cells and other molecular encapsulation approaches to target in vivo delivery. Hydrogel-based strategies can potentially address several current challenges in stem cell therapy. We present a concise overview of the recent advances in applications of hydrogels in stem cell therapies, with a focus particularly on the recent advances in the design and approaches for application of hydrogels in tissue engineering. The capability of hydrogels to either enhance the function of the transplanted stem cells by promoting their controlled differentiation or enhance the recruitment of endogenous adult stem cells to the injury site for repair is also reviewed. Finally, the importance of impacts and the desired relationship between the scaffold system and the encapsulated stem cells are discussed. - 2008-2011 IEEE. Manuscript received June 9, 2017; revised January 8, 2018 and March 14, 2018; accepted March 15, 2018. Date of publication April 12, 2018; date of current version February 15, 2019. This publication was made possible by the NPRP grant [NPRP 9-144-3-021] from the Qatar National Research Fund (a member of The Qatar Foundation) and the grant GCC-2017-005 from GCC research program. The statements made herein are solely the responsibility of the authors. W. Farhat would also like to acknowledge the partial funding for his work by the French Ministry of Europe & Foreign Affairs. A. Hasan would like to thank the Biomedical Research Center at Qatar University for its resources to Anwarul Hasan’s lab. (Corresponding authors: Anwarul Hasan; Firas Kobeissy.) W. Farhat is with the College of Natural Resources, Department of Forest Biomaterials, North Carolina State University, Raleigh, NC 27695 USA, with the Université de Lyon, Ingénierie des Matériaux Polymères (IMP), UMR CNRS 5223, Université Jean Monnet, Saint-Etienne F-42023, France, and also with the Faculty of Medicine, Department of Biochemistry and Molecular Genetics, American University of Beirut Medical Center, Beirut 1107 2020, Lebanon (e-mail: farhatw92@gmail.com). Scopus

The results reported in this document first contribute to the development of an innovative plant-based concrete using raw rice husk. This crop residue is available throughout the year at low cost and its use to manufacture bio-based concretes for green building provides a new recovery sector for a local by-product coming from rice farming in France.

Unlike Portland cement, the use of lime goes back much further in time. During the Greco-Roman period, walls were built of lime-based mortars blended with fine sand and pozzolanic additives (volcanic ash).

Many by-products of plant origin have been incorporated in mineral binders. However, it is important to distinguish plant fibers used as reinforcement in cement composite materials from plant-derived aggregates used for the manufacturing of lightweight insulating concretes (bio-based concretes).

Hemp concrete is obtained from the mix of hemp shiv, water and a mineral binder (which can be itself a mixture of different binders).

This paper aims at studying the shear behavior of glass beads samples through experimental triaxial tests as regards the case of 4 mm diameter glass beads. Repeated tests are systematically carried out, together with the evaluation of the repeatability. Study of numerous experimental conditions is performed: compactness state (high/medium density), variable effective confining pressure ( $$p'_0$$ = 50–200 kPa), saturation state (saturated/dry) and surface state (rough/smooth). Specifically, the influence of these parameters on the stick-slip phenomenon is reported. Equivalent study of perturbation on the mechanical response by larger size spherical inclusions is also performed. The experimental findings received from drained triaxial tests classically throw light on the shear behavior of granular media directly dependent on compactness, in addition to the application of effective confining pressure, with a more dilatant behavior with the decrease of the confining pressure. The Rowe’s law is truly verified in experiments. The modification of the surface state of glass beads results into observably different responses on both the deviatoric and the volumetric aspects. It is quite evident that the intensity of stick-slip phenomenon experienced increase with the application of confining pressure and depends on the surface roughness. No noteworthy impact on the mechanical response is taken into observation between the states of entire saturation and dry. Calculation of friction and dilatancy angles are made as well as reported in respect of different experimental configurations.

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; The compatibilization of PC/PS (70/30 wt%) blends was realized by the addition of 1.125, 2.5 and 5 wt% of SEBS-g-PC. SEM pictures revealed that the droplet-matrix microstructure was refined, from droplets of 0.787 μm diameter to 0.420 μm. The complex viscosity decreased, and, correlated to the size of the droplets, was the result of the decrease of the interfacial tension between PC and PS. The transition temperature of the PS increased for 12 °C with 5 wt% of SEBS-g-PC, showing a compatibilizing effect of this copolymer. The two maxima observed in Van Gurp-Palmen plots merger confirming the compatibilization. Finally, mechanical properties were widely improved. Impact strength evolved from 3.8 to 6.9 kJ m−2, and elongation at break was multiplied by two (from 19.6 to 40.5%) when 5 wt% of copolymer is added. The interfacial adhesion increase was due to the compatibilization effect of the SEBS-g-PC onto PC/PS blends.

This research aims at studying the shear behavior of homogeneous and heterogeneous granular materials by the triaxial test. The research work is performed on glass beads both in laboratory tests and by numerical simulations in DEM. The experimental tests are firstly performed on mono-disperses beads, then expanded to heterogeneous cases like bi-disperses mixtures. For numerical simulations, a cylindrical rigid wall boundary condition, based on Lame formula is implemented, and a series of procedures is proposed to simulate the conventional triaxial test in similar conditions to experimental tests. The numerical and experimental results are compared for both mono-disperses and bi-disperses cases. The numerical model can reproduce deviatoric curves satisfactorily in all experimental conditions.

This paper presents the results of an experimental investigation on the substitution of natural sand by municipal solid waste incineration (MSWI) bottom ash in concrete applications in order to preserve non-renewable natural resources and then, reduce the carbon footprint of buildings sector. First of all, physical, chemical and leaching test have been performed on upgraded MSWI bottom ash and the obtained results were compared to natural sand usually used in France in concrete applications. In the second time, a preliminary campaign carried out by utilizing 100% MSWI bottom ash 0-2 mm for the substitution of natural sand in the mortar applications. Physical characterization revealed that grain size distribution and specific gravity of MSWI bottom ash are similar to natural sand identified. However, water absorption content (WAb equal to 7.50%) of bottom ash is higher than natural sand. In order to improve the workability of mixing, a superplasticizer has been used at 0%, 1.5%, 2% and 3% by weight of cement. After 14 days of curing, compressive and flexural strengths were performed on hardened samples. Results showed compressive strength of bottom ash samples ranging from 19.4 MPa (without superplasticizer) to 33.3 MPa (3% of superplasticizer), following a linear trend while flexural strength ranging 4.7 MPa to 5.4 MPa. No health threat has been detected for the MSWI bottom ash 0-2 mm fraction and it was categorized as non-hazardous waste according to European legislation of waste. Study developments are currently oriented towards the analysis of physical, mechanical and thermal properties of concrete containing bottom ash and durability assessment.

International audience; Hemicelluloses, due to their hydrophilic nature, may tend to be overlooked as a component in water-resistant product applications. However, their domains of use can be greatly expanded by chemical derivatization. Research in which hydrophobic derivatives of hemicelluloses or combinations of hemicelluloses with hydrophobic materials are used with to prepare films and composites is considered herein. Isolation methods that have been used to separate hemicellulose from biomass are also reviewed. Finally, the most useful pathways to change the hydrophilic character of hemicelluloses to hydrophobic are reviewed. In this way, the water resistance can be increased and applications of targeted water-resistant hemicellulose developed. Several applications of these materials are discussed.

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.

MSWI bottom ashes constitute particular granular materials because these industrial by-products are the results from the incineration of domestic waste. The field of beneficial use of these waste mainly lies in the road engineering today, like materials of substitution for the traditional natural aggregates, which are usually used in this field. For this reason, the characterisation of the mechanical behaviour of the material—which is currently little developed—proves to be essential in order to perennalize this field of beneficial use, assuring thus the transition “waste MSWI”/“material MSWI”. This paper presents a first approach of the mechanical behaviour under shear triaxial tests. A special methodology is investigated for the realisation of tests, because of the origin and the specificity of the MSWI bottom ash. The analysis of the mechanical behaviour shows a mechanical behaviour similar to the classic granular materials initially dense.

Microstructural studies of Poly(vinyl alcohol-co-vinyl acetate)-g-polycaprolactone (PVA-Ac)-g-(PCL) were realized principally using NMR. Initial PVA-Ac has a rather blocky structure with an average sequence length of PVA units equal to 12.5. During the synthesis of the studied (PVA-Ac)-g-(PCL), alcoholysis and transesterification reactions led to PCL grafts with acetate end groups. These reactions typically concern 2–5.5% of the total acetate groups. The influence of the local tacticity on the alcohol triad reactivity was evidenced and explained the incomplete functionalization of the PVA-Ac hydroxyl groups. Alcoholysis reactions were also evidenced but with a very low rate in the tested conditions. Caprolactone homopolymerization was not observed. Other properties of the final synthesized copolymers were also presented. Crystallinity totally disappeared in the (PVA-Ac)-g-(PCL). The glass transition temperature was perfectly adjustable by the Fox law without significant modification of the viscoelastic properties characterized by dynamic rheology.

International audience; Then polystyrene supramolecular networks were prepared by radical copolymerization of styrene with monomers containing donor–acceptor (DA) moieties methacrylamide (MAAM) or 2-methacrylamidopyridine (MAP). The molar percentages of MAAM and MAP in the copolymers were, respectively, 2–20% and 6–40%. The glass transition temperatures (Tgs) of these copolymers have been modeled by the Kwei equation showing secondary interactions due to intermolecular hydrogen bonds. The DA-AD association constants (K) have been calculated by 1H NMR spectroscopy of MAAM and MAP. These constants were, respectively, 6.75 and 16.75 M−1. Dynamic mechanical analyses by frequency and temperature sweep tests, were carried out in the molten state. Styrene–MAP or styrene–MAAM copolymers had higher moduli than neat polystyrene but the MAP influences the materials’ properties distinctively from the MAAM. MAP copolymers had a second G′ plateau that appeared at 150 °C, thus showing the formation of a supramolecular network.

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

International audience; Poly (butyl methacrylate-co-methacrylic acid) copolymers/calcium carbonate (CaCO3) composites were synthesized by radical polymerization. Ca2+ cationic sites, present at the CaCO3 surface, in interaction with carboxylate groups from polymer chains structured the material, particularly above the glass transition temperature. The composites were studied by transmission electron microscopy, X-ray diffraction, and dynamic mechanical analysis. Multiplets and clusters were detected. The material's behavior is principally controlled by the methacrylic acid (MA) content in the copolymer chain and CaCO3/MA ratio. Under well-defined conditions, ionic cross-linked materials were obtained.

A one-step process is reported to directly synthesize blends of poly(trimethylene carbonate) (PTMC) with a modified granular starch. Trimethylene Carbonate (TMC) ring-opening polymerization is performed in the presence of native starch particles in bulk conditions at 150 °C and the efficiency of metal-free organic catalysts (TBD and phosphazene superbases P1-t-Oct, P2-t-bu, and P4-t-bu) are investigated to replace the organo-metallic stannous octanoate initiator. TMC monomer is successively converted into PTMC and the robustness of organic catalysts is highlighted with significant activities at very low concentrations (

International audience; Transesterification of poly(lactic acid) and poly(ethylene-co-vinylalcohol) was realized in-melt using different catalysts. Reactions were first conducted in an internal mixer and the different reaction parameters effect on exchange reactions and the obtained copolymers were optimized. Among the used catalysts, 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) and Tin(II) bis(2-ethylhexanoate) (Sn(Oct)2) were particularly efficient. In a second part, reactions were made by reactive extrusion. In most of reaction conditions, compatible blends were obtained with a fine micro phase separation. Only under extreme reaction conditions, high temperature and intensive mixing, nanostructured graft copolymers were obtained.

International audience; The reactions between polycarbonate (PC) and polystyrene-block-poly(ethylene-butylene)-block-polystyrene-grafted-maleic anhydride (SEBS–g–MAH) is a novel, convenient, solvent-free, and easy way to create SEBS–g–PC in order to compatibilize polystyrene and PC blends. This study determines the most efficient catalyst among Tin (II) bis(2-ethylhexanoate) (SnOct2), 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD), Titanium tetrabutoxide (Ti(OBu)4) and Sodium 4-hydroxybenzenesulfonate dihydrate (SHBS) in the molten state at 220 °C. From 20 to 30 wt% of SEBS-g-MAH (or KFG) chains became insoluble. The size exclusion chromatography analyses showed the formation of a double distribution due to PC chains scission and grafting reactions onto SEBS–g–MAH with the exception of the Ti(BuO)4 use. Fine microstructures with a percolation effect proved the efficiency of both the TBD and the SnOct2. The PC transition temperature decreased in at least 10 °C, confirmed that only SnOct2 and TBD were efficient to catalyze the grafting reactions. No evolution was observed with the SHBS and Ti(OBu)4.

Polypropylene (PP) was functionalized in the melt by grafting polar monomers using an internal mixer and a corotating twin-screw extruder. 2,5-Bis(tertbutylperoxy)-2,5-dimethylhexane (Luperox 101) and dicumyl peroxide (DP) were the used radical initiators. The polar monomers were itaconic acid (IAc), 2-octen-1-ylsuccinic anhydride (OY), 2-hydroxyethyl methacrylate (HEMA), and 3-allyloxy-1,2-propanediol (AP). Grafting was quantified by FTIR combined to Elemental Analysis. Grafting degree depends mainly on monomer and initiator natures and concentrations. Grafting degree maxima were 3.9, 2, 9.5, and 3.9 wt %, respectively, for IAc, OY, HEMA, and AP. Some properties of the modified PP were evaluated. Thermal analysis indicated that the polarity of PP increased by grafting reaction and size-exclusion chromatography showed that the grafting was not accompanied by a significant Mw and viscosity decrease. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

International audience; Polypropylene/poly(3-hydroxybutyrate-co-hydroxyvalerate) blend (PHBV) and polyethylene/PHBV blend were prepared by twin screw extruder using preformed copolymer (EVOH-g-PHBV) as compatibilizer or with functional polyolefins that can react in situ with the PHBV phase to form POs-g-PHBV. Scanning electron microscopy shows that by using either EVOH-g-PHBV preformed copolymer or formed copolymers in situ both emulsify the phase interface and reduce the interfacial tension, which result in an enhancement on the mechanical properties of compatibilized blends. Enhancement is more or less pronounced depending on the used PO matrix.

Municipal Solid Waste Incineration (MSWI) bottom ashes are irregular granular media because of their origin and are very heterogeneous with a large quantity of angular particles of different chemical species. MSWI bottom ash is a renewable granular resource alternative to the use of non-renewable standard granular materials. Beneficial use of these alternative granular materials mainly lies in road engineering. However, the studies about mechanical properties of such granular media still remain little developed, those being mainly based on empirical considerations. In this paper, a study of mechanical behaviour of a MSWI bottom ash under axisymmetric triaxial loadings conditions is presented. Samples are initially dense after Proctor compaction, are saturated and tested in drained conditions, under different effective confining pressures ranging from 100 to 600 kPa. The evolutions of volumetric strains show an initial contracting phase followed by a dilatancy phase, more pronounced when the confining pressure is low. The stresses ratios at the characteristic state and at the critical state appear in good agreement and with a null rate of volume variation. The angles of internal friction and dilatancy of the studied MSWI bottom ash are estimated and are similar to conventional granular materials used especially in road engineering. The dilatancy law of Rowe is well experimentally verified on this irregular recycled granular material.

International audience; Novel polyurea-urethane (PUU) supramolecular polymer networks based on triuret and tetrauret blocks were synthesized. The network formation was controlled through the conformation of hydrogen bonding moieties and their concentration. FTIR spectroscopy and solubility tests showed the presence of significant hydrogen bonds only in triuret moieties and that these bonds conducted to cross-linked materials at room temperature. Hydrogen bonding association constant, K-assn = 95 M-1, was calculated using H-1 NMR for triuret blocks' self-associations. Dynamic mechanical analysis confirmed that triuret blocks conduct to a network at room temperature and that decross-linking occurs between 105 and 135 degrees C. The tetrauret blocks had a folded conformation at room and relatively low temperatures. The polymers containing these moieties did not cross-link at room temperature and below. Temperature increase favored unfolded conformation and conducted to intermolecular hydrogen bonds and, at high temperature, to cross-linked materials.

International audience; Poly(ethylene-co-vinylalcohol)-grafted-poly(3-hydroxybutyrate-co-hydroxyvalerate) (EVOH-g-PHBV) was prepared by a catalyzed grafting of PHBV onto immiscible EVOH. These reactions were performed at high temperature in the molten state. The choices of Tin(II) bis(2-ethylhexanoate) (Sn(Oct)2) and 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD), as catalyst, were justified by a first study in an internal mixer. The catalyst quantity, reaction temperature and reaction time were optimized to apply them in the conditions of a reactive extrusion process with a co-rotating twin screw extruder. High reaction temperature, from 180 °C to 220 °C, associated to intensive mixing led to efficient grafting of PHBV onto EVOH, compatible with short residence times required. Rheological, thermal and morphological analyses were conducted to characterize the obtained copolymers. Molecular weights were determined by SEC. SEM imaging were made on cryo-fractured surfaces of blends extruded with and without catalyst. In most of reaction conditions, a compatible blend was obtained with a fine micro phase separation. Graftedcopolymers were only obtained when well defined and controlled conditions are applied.

International audience; The non-miscibility of the reactants during solvent free poly-ε-caprolactone grafting onto poly(ethylene-co-vinyl alcohol) (EVOH) dramatically affects reaction kinetics. Different solutions were proposed to accelerate the exchange reactions between poly(ethylene-co-vinyl alcohol) and poly-ε-caprolactone. Reactions were conducted in a batch reactor or a mini twin-screw extruder. The addition of a poly(ethylene-co-vinyl alcohol)-g-poly-ε-caprolactone copolymer increased the compatibility of the reactants and led to a higher reaction rate. This copolymer was either prepared separately and added at the reaction beginning or prepared in situ grafting caprolactone from EVOH. The reactive system evolution was analyzed using molar mass evolution, microstructure characterization, thermal properties and the reactive blend morphology. The compatibilization effect combined with optimized reaction conditions, such as concentration and nature of catalyst and temperature, resulted in an important increase in reaction rates. Among the tested catalysts, 1,5,7-Triazabicyclo [4.4.0]dec-5-ene was a more efficient catalyst for grafting reactions than Tin (II) 2-ethylhexanoate.

Polycaprolactone (PCL) grafting on vinyl alcohol-co-vinyl acetate) (PVA-Ac), was investigated in the melt at high temperature (170°C), below the PVA-Ac melting point, by ring opening polymerization of ϵ-caprolactone initiated by metal alkoxyde sites present in PVA-Ac: no additional initiator was used. The obtained average structures were determined by 1H NMR. As expected, small grafts, with low average polymerization degree (DP), were obtained, between 4 and 12 h of reaction. These DP are due to exchange reactions between hydroxyl groups and PCL growing chains. The PVA-Ac was shown to be partially substituted by short PCL grafts. The DP linearly increased with the initial Lactone/PVA-Ac ratio, and the substituted alcohol sites rate were limited to 63%.It was shown that the used reactive system is characterized by a quazi-living polymerization mechanism. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007