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In the last decades, the amount of dredged sediments (DS) increased in France harbours. Dredged sediments consist of fine soil collected from the deepening, broadening and maintaining of public waterways. The present study reports the investigation of the beneficial reuse of dredged sediments collected from Le Havre (France) harbour as fired material for sustainability requirements. The main challenge is the use of untreated dredged sediments from land deposit of the Seine estuary and port areas as building material, especially for fired bricks manufacture. The chemical, mineralogical and particle size compositions of the raw material were assessed using X-ray fluorescence (XRF), X-ray diffraction (XRD) and laser particle sizer, respectively. The results indicate that the main oxide components are SiO2 and CaO3, while quartz and calcite are the main mineral phases. Lesser amounts of feldspar, chlorite, kaolinite, muscovite and halite were also determined. The physical properties of the raw clay material, including plasticity, organic content and salinity, were investigated in order to assess the product suitability as building material. Ceramic properties such as linear shrinkage, water absorption, bending strength and mineral neo-formations were also investigated in fired bricks at temperatures ranging from 700 to 1000 °C. A high mechanical strength has been obtained at a temperature of 900 °C. The use of ternary diagrams indicates that the raw material falls inside the industrial domain, and ceramic tests show that the raw material could be used in brick making because of its firing behaviour and mechanical resistance. As regards environment sustainability, chemical analysis reveals that the levels of metal traces from leaching tests remain low and within regulatory limits.

Made available in DSpace on 2020-12-12T02:41:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Brazil is the second-largest world producer of pineapple and generates almost 45% of its initial mass in wastes after industrialization, mainly due to the inappropriate deposition of peel and crown, which contribute to environmental damage. In this study, pineapple crown fibers (PCF) residues were investigated as an essential alternative to produce cellulose nanocrystals (CNC). It was used a free-chlorite hydrolysis reaction combined with sulfuric acid using different times and acid concentrations to obtain CNC after obtaining of the bleached cellulose. CNC`s were characterized by zeta potential, TGA, XRD, FTIR, and TEM. The main results showed that the chemical treatments were efficient in the removal of amorphous components, increasing the fiber whiteness and the crystallinity index. The best result obtained was for a concentration of 64% of H2SO4 for two hours with values of particle size of c.a. 140 nm and Zeta potential of − 47.96 mV, validating the use of the PCF for CNC. Department of Materials and Technology State University of São Paulo-UNESP LOMC CNRS ULH Normandie University Department of Materials and Technology State University of São Paulo-UNESP FAPESP: Process n 2015/10389-9

A cotransport study of heavy metals and kaolinite particles in sand column with and without flax geotextiles was carried out. The objectives were to evaluate the potential role of kaolinite in heavy metals transfer and to analyse the influence of flax geotextiles on the transfer of these pollutants. The adsorption rates of heavy metals on the kaolinite particles were, respectively, 53%, 65% and 25% for copper, lead, and zinc. The injection of kaolinite with heavy metals resulted in a significant decrease in the retention efficiency of copper and lead in the filter. The presence of kaolinite in the injected solution has virtually no influence on the effectiveness of zinc fixation in the filter. The retention of heavy metals is in the order of Zn > Cu > Pb with a significant drop of retention efficiency of 34% for copper, 67% for lead, and less than 1% for zinc. The presence of kaolinite in the injected solution reversed the retention order of heavy metals when metals solution was injected alone. Flax geotextiles increase the ability of the filter to retain soluble and attached heavy metals. It improves the sand retention capacity and it retains soluble and attached metals in its structure.

Hypothesis The temperature dependence of the static contact angle could a priori be predicted by using surface tension partitioning. An original model based on the transition state theory is also introduced. This model considers thermocapillary fluctuations on the droplet surface near the triple line and the self-affine pinning of this triple line against a solid substrate modeled with a pseudo-periodic distribution of adsorption sites. Experiments The temperature dependence of the static contact angle was studied for a representative range of liquids with different polarities and on a wide array of solid substrates for temperatures ranging from 25 to 240 °C. Atomic force microscopy (AFM) was also used to quantify the surface roughness of the solid substrates. Findings Whereas the surface tension partitioning failed to bring consistent results above room temperature, the transition state model proved very useful, thereby opening a way to yield predictive contact angle values with temperature variations. The introduction of a topological dimension in the equations yields a unified model that covers normal wetting (perfectly bonded liquids on smooth surfaces) but also the onset of Cassie-Baxter and Wenzel states on real surfaces. Moreover, the model encompasses the transition to complete wetting.

International audience; Cellulose nanocrystals (CNC) and xyloglucan (XG) were used to construct new aerogels inspired by the hierarchical organization of wood tissue, i.e., anisotropic porous cellular solid with pore walls containing oriented and stiff cellulose nanorods embedded in hemicellulose matrix. Aerogels with oriented or disordered pores were prepared by directional and non-directional freeze-casting from colloidal dispersions of XG and CNC at different ratios. XG addition induced a clear improvement of the mechanical properties compared to the CNC aerogel, as indicated by the Young modulus increase from 138 kPa to 610 kPa. The addition of XG changed the pore morphology from lamellar to alveolar and it also decreased the CNC orientation (the Hermans’ orientation factor was 0.52 for CNC vs 0.36−0.40 for CNC-XG). The aerogels that contained the highest proportion of XG also retained their structural integrity in water without any chemical modification. These results open the route to biobased water-resistant materials by an easy and green strategy based on polymer adsorption rather than chemical crosslinking.

International audience; This work consists in an experimental investigation of forced dynamic wetting of molten polymers on cellulosic substrates and an estimation of models describing this dynamic. A previous work of Pucci et al. (2018) showed that for totally wetting liquids (as paraffin oils), temperature-induced variations in dynamic wetting are included into the capillary number (Ca) and then a master curve of dynamic contact angle (θ d) as a function of Ca can be obtained. The hydrodynamic theory (HDT) correctly describes the dynamic wetting for Ca > 2 · 10 −3. For lower Ca, a change in the dynamic wetting behavior was observed. Here, partially wetting liquids (polyethylene glycols, a.k.a. PEGs) at different molecular weight (Mn) were used at temperatures above their melting point to investigate the dynamic wetting behavior on cellulosic substrates for a large range of Ca. It was found that the dynamic curves of θ d vs. Ca depend on Mn. Moreover, the HDT correctly describes the experimental measurements for Ca > 2 · 10 −3. Below this threshold the dynamic contact angle decreases toward the static one. A linear correlation between parameters obtained fitting the HDT and the molecular weight of polymer was found. The prediction of dynamic wetting for low Ca (Ca < 2 · 10 −3) with the molecular kinetic theory (MKT) was also evaluated and discussed.

To overcome water scarcity issues in arid and semi-arid regions, Managed Aquifer Recharge (MAR) remains a viable and suitable solution to manage and restore aquifers. However, clogging represents a major issue that can affect the durability and efficiency of MAR structures. The aim of this study was to evaluate the extent of clogging in MAR sites (Berrechid, Morocco). To achieve this objective, two field-based studies were undertaken: the first one consists of implantation of sand-filled columns in the recharge sites to evaluate the surface and subsurface clogging. The second one consists of the implantation of pickets over a 750 m2 area in each recharge site to measure the extent of deposit thickness on the surface of the wadi bed. Results show that, despite the low rainfall (

International audience; Filtration tests were carried out in laboratory columns filled with crushed sand with and without flax geotextiles to study the transfer and retention of soluble heavy metals. Divalent cations of copper, zinc and lead were simultaneously and continuously injected in filtration columns. Results show that, when geotextiles discs are present the retention of metals in sand is favoured and retention profiles are modified. In addition, and unlike synthetic geotextiles, flax fibres geotextiles contribute to the retention of a significant fraction of the cationic metal pollutants in their own structure. The overall metals retention efficiency of the filter is improved. Competition between cationic metals for adsorption on retention sites occurs in the column in the order Pb > Cu > Zn. Most of the lead is retained in the inlet of the column while copper and even more zinc migrate deeper in the column.

The effects of fibre orientation and laminate stacking sequence on the mechanical anisotropy of paper-based all-cellulose composites produced via a partial dissolution route is examined. As part of this work, the fibre architecture and microstructure of the paper precursor is controlled and characterised in order to follow the anisotropy of the materials through from precursor to final composite material. The fibre orientation of the precursor was found to strongly influence the mechanical anisotropy of the final composite material. The ultimate tensile strength and Young’s modulus of the paper-based all-cellulose composite laminates was 191 MPa and 17.5 GPa in the fibre direction, respectively, compared with 104 MPa and 10.4 GPa in the transverse direction, respectively. The ACC crystal structure was assessed with powder and transmission mode Wide-angle X-ray diffraction (WAXD) to measure the changes in crystallinity and crystal orientation due to the dissolution process. The mechanical response of multi-axial all-cellulose composite laminates was also determined experimentally and compared with analytical predictions by Classical Lamination Theory, demonstrating the utility of CLT for the prediction of the elastic properties of ACC laminates.

X-ray powder diffraction is one of the most commonly used methods in cellulose science. This technique is used to identify the cellulose allomorphs, their crystallinity, and the size of their crystallites. In this paper, a novel model is introduced that implicitly takes into account the shape and size of cellulose Iβ crystallites in the interpretation of powder diffractograms. Because of the limited amount of data in cellulose powder patterns, this model focuses on a small number of adjustable parameters. The method hypothesizes that cellulose Iβ crystallites are straight crystalline rods with superelliptical cross-sections. This superellipse is a parametric curve that can, for example, describe various crystallite shapes as rectangles or ellipses. Additionally, preferred orientation along the (0 0 1) crystallographic planes can be modelled using the March–Dollase approach. The simulated background has a semi-empirical form. An initial model comprised cellulose Iβ crystallites and the amorphous background. A second model comprised a biphasic distribution of crystallites and the same amorphous background. In this second model, large cellulose Iβ crystallites coexisted with more slender crystallites, usually less than 20 A in lateral size. Cellulose IVI nanocrystals were selected as a modeling construct to represent these small and distorted forms of native cellulose. Both models produced simulations in excellent agreement with the experimental measurements.

A cotransport study of heavy metals and kaolinite particles in sand column with and without flax geotextiles was carried out. The objectives were to evaluate the potential role of kaolinite in heavy metals transfer and to analyse the influence of flax geotextiles on the transfer of these pollutants. The adsorption rates of heavy metals on the kaolinite particles were, respectively, 53%, 65% and 25% for copper, lead, and zinc. The injection of kaolinite with heavy metals resulted in a significant decrease in the retention efficiency of copper and lead in the filter. The presence of kaolinite in the injected solution has virtually no influence on the effectiveness of zinc fixation in the filter. The retention of heavy metals is in the order of Zn Cu Pb with a significant drop of retention efficiency of 34% for copper, 67% for lead, and less than 1% for zinc. The presence of kaolinite in the injected solution reversed the retention order of heavy metals when metals solution was injected alone. Flax geotextiles increase the ability of the filter to retain soluble and attached heavy metals. It improves the sand retention capacity and it retains soluble and attached metals in its structure.

Negative size effects are commonly reported for advanced composite materials where the strength of the material decreases with increasing volume of the test specimen. In this work, the effect of increasing specimen volume on the mechanical properties of all-cellulose composites is examined by varying the laminate thickness. A positive size effect is observed in all-cellulose composite laminates as demonstrated by a 32.8% increase in tensile strength as the laminate thickness is increased by 7 times. The damage evolution in all-cellulose composite laminates was examined as a function of the tensile strain. Enhanced damage tolerance concomitant with increasing specimen volume is associated with damage accumulation due to transverse cracking and strain delocalisation. A transition from low-strain failure to tough and high-strain failure is observed as the laminate thickness is increased. Simultaneously, scale effects lead to an increase in the void content and cellulose crystallinity at the core, with increasing laminate thickness.

All-cellulose composites are high performing green materials and solvent infusion processing makes their upscaled manufacturing possible. This study explored the use of aqueous 7 wt.% NaOH/12 wt.% urea solution as cost effective and environmentally friendly cellulose solvent for solvent infusion processing. A short dissolution time of 5 min led to all-cellulose composite laminates with a tensile strength of 114 ± 1.9 MPa and a Young’s modulus of 7.8 ± 0.5 GPa. A decrease of tensile strength and Young’s modulus with increasing dissolution time from 5 to 60 min was linked to changes in composite microstructure and fine structure of the reinforcing rayon fibres. It was shown that aqueous NaOH/urea solution is a promising alternative solvent, as it offers the advantages of shorter processing times and reduced solvent costs by 97%, while resulting in 25% stronger laminates, when compared to using ionic liquids.

The potential for a facile aqueous-based solvent processing route for the synthesis of all-cellulose composites (ACCs) is explored using aqueous solutions containing tertabutylphosphonium hydroxide (TBPH). Specifically, ACC laminates are prepared via the partial dissolution of a woven textile of cellulose II using aqueous TBPH solutions. The dissolved cellulose was then regenerated to reform a cellulose II matrix phase in situ that acts to bond the original undissolved fibres. The hygroscopic behaviour and dissolution analysis of the solvent system showed wide range in the choice of processing conditions suited to the production of ACC laminates via TBPH. The effect of solvent concentration on the microstructure, crystallinity and tensile properties of ACCs is reported. The use of TBPH enables reductions in the processing cycle time and improved control over the properties of ACCs, indicative of a promising solvent system for the upscaled production of ACCs and their laminates.

The processing of natural biopolymers by Fused Deposition Modeling (FDM) opens perspectives for applications in food and health domains by taking advantages of their edibility, biocompatibility and bioresorbability. Glycerol plasticized zeins (proteins from maize kernels) present thermomechanical properties matching the extrusion step requirements of FDM (at Tprinting=130°C for 20% of glycerol). The present work focuses on the fusion-bonding step of the process between adjacent filaments. Mechanisms at the root of the thermal bonding of amorphous polymers at T>Tg are governed by melt’s surface tension (Γ, driving force) and viscosity (η, limiting force). In addition, healing phenomenon, assessed by the degree of healing, Dh, increases with time as Dh∝t1/4. It originates from the diffusion of polymer chains across the interface in accordance with the reptation theory. Dynamic rheological properties of molten extruded filaments of plasticized zeins were determined in a pre-heated oscillatory rheometer at 130°C, with |η ∗ |γ˙ =1.6s−1 ranging from 0.6 to 0.8kPa.s. Γ was estimated from the evolution of the fusion-bonding neck growth between two extrudates (polymer sintering model). The 0.1mm.s−1 bonding rate observed at 130°C allowed estimating a melt surface tension of 30-40mN.m−1. Concurrently surface energy measurements were conducted on solid plasticized zein at 20°C using the sessile drop method: By varying liquids deposited on zein-based surface and following Owens and d−1 Wendt’s approach, ySV was found to amount to 39.2±1.6mN.m−1, with the dispersive component γSVd=4.2±0.4mN.m−1 and the polar one γSVp=35.0±1.2mN.m−1 These values were used to extrapolate a melt surface tension using the typical surface tension dependence dγ/dT≈-0.05mN.m−1.K−1 like for synthetic polymers following the Eotvos’ law. The extrapolated values at 130°C were in agreement with those obtained from fusion-bonding experiments.The processing of natural biopolymers by Fused Deposition Modeling (FDM) opens perspectives for applications in food and health domains by taking advantages of their edibility, biocompatibility and bioresorbability. Glycerol plasticized zeins (proteins from maize kernels) present thermomechanical properties matching the extrusion step requirements of FDM (at Tprinting=130°C for 20% of glycerol). The present work focuses on the fusion-bonding step of the process between adjacent filaments. Mechanisms at the root of the thermal bonding of amorphous polymers at T>Tg are governed by melt’s surface tension (Γ, driving force) and viscosity (η, limiting force). In addition, healing phenomenon, assessed by the degree of healing, Dh, increases with time as Dh∝t1/4. It originates from the diffusion of polymer chains across the interface in accordance with the reptation theory. Dynamic rheological properties of molten extruded filaments of plasticized zeins were determined in a pre-heated oscillatory rheometer at 13...

Four sources of cellulose with different molecular weights were dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate at 100 °C over a 10 h period. The solution densities were determined and these results were subsequently utilised to access the influence of dissolved cellulose on surface tension properties of cellulose/ionic liquid solutions. Surface tension measurements revealed increasing molecular weight and concentration reduced surface tension while temperature increases showed the opposite effect. These results are consistent with that of repulsive polymer-wall interactions near the interface in good solvent conditions. The semi-flexible nature of this carbohydrate in solution can help explain deviations of these results when compared to ideal flexible chains.

All-cellulose composites were produced by partial dissolution of two cellulosic sources in a mixture of sodium hydroxide and urea at low temperature. Filter paper (FP) and microfibrillated cellulose (MFC) were used to examine the role of the fiber dimensions of the initial reinforcing network on the final mechanical properties of thin self-reinforced all-cellulose composites. The dissolution time was used to control the extent of the transformation. The initial fiber structure was progressively transformed into a thoroughly consolidated composite material. X-ray diffraction and Fourier-transform infrared spectroscopy were able to show that the initial cellulose I allomorph was replaced with a cellulose II allomorph. FP underwent a fast crystallinity loss and transformation to cellulose II. In contrast, the crystallinity of MFC decreased slowly after dissolution. This result was also correlated with a slower allomorphic transformation. The crystallinity of MFC decreased to a level comparable to that of FP after 40 min and it remained comparatively unaffected at extended dissolution times. Comparison between powder and transmission XRD measurements demonstrated that the cellulose II present in all films after dissolution was strongly textured with its (1 $$\bar{1}$$ 0) plane lying parallel to the sample surface despite fibrous microstructural features remaining from the initial substrates. The tensile strength and elastic modulus of FP increased significantly (+690 and +528 %, respectively) after only 20 min, while that of MFC remained relatively unaltered as a function of the dissolution time.

International audience; All-cellulose nanocomposites reinforced by cellulose nanocrystals (CNC) were produced using a solvent consisting of 1-butyl-3-methylimidazolium chloride and dimethyl sulfoxide. Microcrystalline cellulose (MCC) was pre-dissolved at high temperature in the solvent. Freeze-dried CNC were then added to the slurry at room temperature, thereby avoiding complete CNC dissolution. Solid all-cellulose composite films were obtained by film casting, solvent exchange and drying. The MCC to CNC ratio was kept constant while the solvent content was incremented. The short-range and long-range cellulose–cellulose interactions in the solid materials were respectively assessed by Fourier-transform infrared spectroscopy and X-ray diffraction. The CNC used in this work contained both cellulose I and cellulose II. The cellulose concentration in the mixture drastically changed the overall crystallinity as well as the cellulose I to cellulose II ratio in the ACC. Cellulose II was formed by recrystallisation of the dissolved fractions. These fractions include the pre-dissolved MCC and the cellulose II portion of the CNC. Cocrystallisation with the cellulose I CNC acting as a template was also evidenced. This phenomenon was controlled by the initial solvent content. The correlation between the hygromechanical properties and the nanostructure features of the ACC was investigated by humidity-controlled dynamic mechanical analysis (RH-DMA). The introduction of the cocrystallisation and percolation concepts provided a thorough explanation for the humidity dependency of the storage modulus.

International audience; Clathrate hydrates are icelike crystalline compounds with encaged guest molecules trapped inside the cages of hydrogen bonded water molecules. Their growth is visualized for cyclopentane within water drops of two microliters on glass and poly-tetrafluoroethylene surfaces. The effect of the interfacial tension between water and cyclopentane is measured at different temperatures and for different concentration of an oil-soluble surfactant: sorbitan monooleate (Span 80). The drops experience a temperature sequence where they freeze into ice, form hydrates and melt. Cyclopentane hydrates crystals are affected by the concentration of surfactant. The morphology seen here could be relevant for explaining the behavior of hydrate emulsions.

International audience; The present research focuses on the alkyl polyglucoside, a non-ionic surfactant, in combination with a fatty alcohol of the same chain length used as a co-surfactant. A series of solutions were prepared, with varying both APG/ FA ratio and its concentration in water. Different structures were then obtained, depending on these two parameters: aqueous micellar solutions, normal hexagonal liquid crystalline phase, α-gel phase, as well as the mixture of normal hexagonal/α-gel phases. A specific term "auto-emulsion" was introduced to describe the pseudo emulsions formed by the APG ≤ FA containing solutions because of the fatty alcohol, which dispersion in water was similar to an emulsion representation. The presence of the liquid crystals was revealed by optical microscopy under the polarized light, as different anisotropic conformations corresponding to the lamellar phase, the hexagonal phase and the coexistence of the lamellar and hexagonal phases, mainly for the most concentrated samples, were observed. These structures were characterized at the molecular level through the wide-angle X-ray diffrac-tion technique and their macroscopic behaviour was investigated by rheology tests. Two main observations were then made: the variation of the surfactant concentration in solution promotes the transition between micellar region towards the liquid crystalline formation zone, while the APG/FA ratio impacts the formation of hexagonal phases (APG N FA) or of lamellar ones (APG b FA).

International audience; In this work, the properties of cellulose (CE)/xyloglucan (XG) biopolymer blends are investigated, taking inspiration from the outstanding mechanical properties of plant cell walls. CE and XG were first co-solubilized in an ionic liquid, 1-ethy1-3-methylimidazolium acetate, in order to blend these biopolymers with a varying CE:XG ratio. The biopolymers were then regenerated together using water to produce solid blends in the form of films. Water-soluble XG persisted in the films following regeneration in water, indicating an attractive interaction between the CE and XG. The final CE:XG ratio of the blends was close to the initial value in solutions, further suggesting that intimate mixing takes place between CE and XG. The resulting CE/XG films were found to be free of ionic liquid, transparent and with no evidence of phase separation at the micron scale. The mechanical properties of the blend with a CE:XG ratio close to one revealed a synergistic effect for which a maximum in the elongation and stress at break was observed in combination with a high elastic modulus. Atomic force microscopy indicates a co-continuous nanostructure for this composition. It is proposed that the non-monotonous variation of the mechanical performance of the films with XG content is due to this observed nanostructuration. (C) 2017 Elsevier Ltd. All rights reserved.

International audience; Seven varieties of flax (Linum usitatissimum) fibres were analyzed in order to gain a deeper insight into the morphological features of the crystalline assembly. Different spectroscopic techniques and a chemical bleaching process were used to provide an accurate description of the lateral arrangement of the polysaccharide chains within the fibre cell wall. The flax fibres were analyzed in their natural state and after an extraction treatment of the non-crystalline components such as hemicelluloses, pectins and phenolics. The chemical bleaching process consisted of a Soxhlet extraction in toluene, a sodium chlorite treatment and an alkaline extraction of the residual hemicelluloses. Solid-state 13C nuclear magnetic resonance (NMR) confirmed the sequential removal of the non-cellulosic components from the flax cell wall. Both wide-angle X-ray diffraction (WAXD) and solid-state 13C NMR provided measures of the crystallite thicknesses and overall crystallinities before and after treatment. The existence of non-cellulosic highly ordered paracrystalline domains was also evidenced by proton spin relaxation time calculation. Whereas the overall crystallinity determined by WAXD decreased after treatment, the cellulose crystallinity calculated with the help of the solid-state 13C NMR slightly increased. This is explained by the difference in chemical selectivity between these two techniques and by the paracrystalline state of both hemicelluloses and pectins. Strong adhesion between cellulose crystallites, hemicelluloses and pectins in the fibres was evidenced by low spin–spin relaxation times and by an increase in crystallite thickness after bleaching. A simple model is proposed that describes the rearrangement of the macromolecules during the bleaching process.

The objective of this study is to get a better understanding of radar signal over irrigated wheat fields and to assess the potentialities of radar observations for the monitoring of soil moisture. Emphasis is put on the use of high spatial and temporal resolution satellite data (Envisat/ASAR and Formosat-2). Time series of images were collected over the Yaqui irrigated area (Mexico) throughout one agricultural season from December 2007 to May 2008, together with measurements of soil and vegetation characteristics and agricultural practices. The comprehensive analysis of these data indicates that the sensitivity of the radar signal to vegetation is masked by the variability of soil conditions. On-going irrigated areas can be detected all over the wheat growing season. The empirical algorithm developed for the retrieval of topsoil moisture from Envisat/ASAR images takes advantage of the Formosat-2 instrument capabilities to monitor the seasonality of wheat canopies. This monitoring is performed using dense time series of images acquired by Formosat-2 to set up the SAFY vegetation model. Topsoil moisture estimates are not reliable at the timing of plant emergence and during plant senescence. Estimates are accurate from tillering to grain filling stages with an absolute error about 9% (0.09 m3 m−3, 35% in relative value). This result is attractive since topsoil moisture is estimated at a high spatial resolution (i.e. over subfields of about 5 ha) for a large range of biomass water content (from 5 and 65 t ha−1 independently from the viewing angle of ASAR acquisition (incidence angles IS1 to IS6).

[Departement_IRSTEA]Territoires [TR1_IRSTEA]SYNERGIE [Departement_IRSTEA]Territoires [TR1_IRSTEA]SYNERGIE; The present paper proposes a method for the evaluation of soil evaporation, using soil moisture estimations based on radar satellite measurements. We present firstly an approach for the estimation and monitoring of soil moisture in a semi-arid region in North Africa, using ENVISAT ASAR images, over two types of vegetation covers. The first mapping process is dedicated solely to the monitoring of moisture variability related to rainfall events, over areas in the "non-irrigated olive tree" class of land use. The developed approach is based on a simple linear relationship between soil moisture and the backscattered radar signal normalised at a reference incidence angle. The second process is proposed over wheat fields, using an analysis of moisture variability due to both rainfall and irrigation. A semi-empirical model, based on the water-cloud model for vegetation correction, is used to retrieve soil moisture from the radar signal. Moisture mapping is carried out over wheat fields, showing high variability between irrigated and non-irrigated wheat covers. This analysis is based on a large database, including both ENVISAT ASAR and simultaneously acquired ground-truth measurements (moisture, vegetation, roughness), during the 2008-2009 vegetation cycle. Finally, a semi-empirical approach is proposed in order to relate surface moisture to the difference between soil evaporation and the climate demand, as defined by the potential evaporation. Mapping of the soil evaporation is proposed.

Les donnees acquises par teledetection satellitale ont ete intensivement utilisees pour l’etude des regions agricoles. Dans le domaine spectral solaire, elles ont principalement ete acquises par deux types de systemes, soit a resolution decametrique avec des capteurs a capacite de revisite moderees (15 jours), soit quotidiennement a basse resolution (~1 km). Dans les domaines solaire et micro-onde, plusieurs missions spatiales permettant l’acquisition frequente (tous les 1 a 5 jours) d’images a haute resolution ont ete lancees recemment ou vont l’etre dans un futur proche (FORMOSAT-2, ENVISAT-ASAR, Sentinel-2, Venμs, Rapid-Eye, Terra-SAR, Cosmo-Skymed). L’objectif de cette communication est d’attirer l’attention sur certaines perspectives offertes par ces missions spatiales a hautes resolutions spatiale et temporelle pour l’etude des agro-ecosystemes. Les exemples, issus principalement de recherches menees dans des regions semi-arides a partir de donnees FORMOSAT-2, portent sur la cartographie de l’occupation du sol, la detection des operations agricoles et le suivi de la dynamique des couverts vegetaux. L’interet de ces informations pour la spatialisation de modeles agro-meteorologiques - estimation de la consommation en eau et irrigation des cultures - est egalement discute.

Novel aerogels (or aerocellulose) based on all-cellulose composites were prepared by partially dis- solving microcrystalline cellulose (MCC) in an 8 wt % LiCl/DMAc solution. During this process, large MCC crystals and fiber fragments were progressively split into thinner crystals and cellulose fibrils. The extent of the transformation was controlled by using cellulose concen- trations ranging from 5 to 20 wt % in the LiCl/DMAc solution. Cellulose gels were precipitated and then proc- essed by freeze-drying to maintain the openness of the structure. The density of aerocellulose increased with the initial cellulose concentration and ranged from 116 up to 350 kg m � 3 . Aerocellulose with relatively high mechanical properties were successfully produced. The flexural strength of the materials reached 8.1 MPa and their stiff- ness was as high as 280 MPa. V C 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 216-221, 2010

Fully bio-based and biodegradable all-cellulose composites were prepared in the form of films by partial dissolution of two cellulose sources: a commercially available microfibrillated cellulose (MFC) and filter paper (FP). The solvent selected for this work was the ionic liquid 1-butyl-3-methylimidazolium chloride ([C 4 mim]Cl). Both cellulose sources were partially dissolved at 80 °C and consolidated by partial dissolution, resulting in excellent mechanical properties. X-ray diffraction and electron microscopy demonstrated that partial dissolution was a viable path to transform FP into a continuous paracrystalline matrix reinforced with cellulose I crystallites. In contrast, partially dissolved MFC was not as thoroughly dissolved and large amounts of undissolved material were still visible along the centre line of the films after the longest dissolution times. Consequently, partially dissolved MFC retained its initially high crystallinity. The degree of polymerization of the materials after dissolution was significantly reduced.

The use of fiber from Harakeke (or New Zealand Flax plant) for the reinforcement of composites should be explored since Harakeke has similar properties to Sisal fiber. To maximize the cellulose content in the fiber, Harakeke fibers were prepared by thermal, combinative alkaline-thermal, and a novel combinative thermal-enzymatic-thermal treatments and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and wide-angle X-ray spectroscopy. The characterization method provided an efficient and systematic method to evaluate the removal of amorphous components such as lignin and hemicelluloses. In particular, a sequential thermal-enzymatic-thermal fiber treatment produced fine discontinuous whiskers that could be useful for short fiber composites, whereas a combinative thermal-alkaline treatment resulted in thorough extraction of lignin and hemicelluloses. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Novel all-cellulose composite films were prepared by partly dissolving microcrystalline cellulose (MCC) powder in an 8% LiCl/DMAc solution. Cellulose solutions were precipitated and the resulting gels dried in a vacuum bag to produce films approximately 0.2–0.3 mm thick. X-ray diffraction (XRD) was used to characterise lateral crystal size and transmission electron microscopy (TEM) was employed to assess the morphology of the composites. During dissolution, the fibrous fragments of MCC were split into thinner cellulose fibrils and crystals were progressively broken down into thinner crystals. The composites were tested in tension and fracture surfaces were inspected by scanning electron microscopy (SEM). It was found that the mechanical properties and final morphology of all-cellulose composites was controlled by the rate of precipitation, initial cellulose concentration and dissolution time. The precipitation conditions were found to play a large role in the optimisation of the mechanical properties by limiting the amount of defects that were induced by differential shrinkage. All-cellulose composites were produced with a tensile strength up to 106 MPa and a tensile modulus up to 7.6 GPa.

This paper presents a new method developed for the atmospheric correction of the images that will be acquired by the Venμs satellite after its launch expected in early 2010. Every two days, the Venμs mission will provide 10 m resolution images of 50 sites, in 12 narrow spectral bands ranging from 415 nm to 910 nm. The sun-synchronous Venμs orbit will have a 2-day repeat cycle, and the images of a given site will always be acquired from the same place, at the same local hour, with constant observation angles. Thanks to these characteristics, the directional effects will be considerably reduced since only the solar angles will slowly vary with time. The algorithm that will be implemented for the atmospheric correction of Venμs data is being developed using both radiative transfer simulations and the actual data acquired by the Formosat-2 satellite. Because of its one-day sun-synchronous repeat cycle, Formosat-2 acquires images with a sun-viewing geometry close to the one Venμs will offer. With this geometry, reflectance time series are free from directional effects on the short term, a feature which reduces the number of unknowns to retrieve. The atmospheric corrections algorithm exploits this feature and the two following assumptions: – Aerosol optical properties vary quickly with time but slowly with location. – Surface reflectances vary quickly with location but slowly with time. Consequently, the top of atmosphere reflectance short term variations (10 to 15 days) are mainly due to the variations of aerosol optical properties, and it is thus possible to use these variations to characterise the atmospheric aerosols and to retrieve surface reflectances. This paper first describes the aerosol inversion method we developed and its results when applied to simulations. In the second part, we show the first tests of the method against three data sets acquired by Formosat-2 images with constant observation angles. Aeronet sun photometers measurements were available on all sites. Formosat-2 estimates of optical thickness compare favourably with Aeronet in situ measurements, leading to a noticeable improvement of the smoothness of time series of surface reflectances after atmospheric correction.

International audience; All-cellulose composites were prepared by partly dissolving microcrystalline cellulose (MCC) in an 8.0 wt% LiCl/DMAc solution, then regenerating the dissolved portion. Wide-angle X-ray scattering (WAXS) and solid-state 13 C NMR spectra were used to characterize molecular packing. The MCC was transformed to relatively slender crystal-lites of cellulose I in a matrix of paracrystalline and amorphous cellulose. Paracrystalline cellulose was distinguished from amorphous cellulose by a displaced and relatively narrow WAXS peak, by a 4 ppm displacement of the C-4 13 C NMR peak, and by values of T 2 (H) closer to those for crystalline cellulose than disordered polysaccharides. Cellulose II was not formed in any of the composites studied. The ratio of cellulose to solvent was varied, with greatest consequent transformation observed for c < 15%, where c is the weight of cellulose expressed as % of the total weight of cellulose, LiCl and DMAc. The dissolution time was varied between 1 h and 48 h, with only small additional changes achieved by extension beyond 4 h.