Evelyne Mauret

Chemical composition and pulping of date palm rachis and Posidonia oceanica--a comparison with other wood and non-wood fibre sources.

In the present paper, the valorisation of two residues: Posidonia oceanica and date palm rachis was investigated. First, their chemical composition was studied and showed that they present amounts of holocellulose, lignin and cellulose similar to those encountered in softwood and hardwood. Extractives in different solvents and ash contents are relatively high. Moreover, ash composition assessment showed that silicon is the major component (17.7%) for P. oceanica. The high ash quantity and the low DP (about 370) may be considered as serious disadvantages of P. oceanica, in the pulping and papermaking context. Oppositely, the properties of rachis date palm and those of the ensuing pulp, obtained from a classical soda-anthraquinone cooking, demonstrated the suitability of this agricultural by-product for papermaking. Preliminary tests conducted on unrefined pulp suspensions and handsheets from date palm rachis in terms of freeness, Water Retention Value and mechanical properties allowed confirming the good quality of date palm rachis fibres.

Synthesis and characterization of cellulose carbonate using greenchemistry: Surface modification of Avicel

The development of new derivatives based on renewable natural resources using green chemistry is a concept gaining recognition in several industries. This work focused on the preparation and characterization of cellulose carbonate using dimethyl carbonate as the green reagent in ethanoic KOH solution. The effect of several reaction parameters were evaluated, i.e., temperature (25°C, 50°C, 90°C, 120°C, 150°C, and 180°C), time (6, 24, 48, and 72h), KOH concentration (15% and 30%), and the use of a catalyst (DBU). The degree of substitution (DS) of the resulting materials was evaluated by 13C CP/MAS NMR. The spectra of the prepared cellulose carbonate exhibited the main peaks associated with cellulose macromolecules (C1-C6) and those corresponding to carbonate functions at approximately 162ppm. Moreover, XPS was performed and confirmed the reaction modifications. Nevertheless, it is worth noting that 13C NMR and XPS spectra showed a significant difference in DS value, due to the difference between both techniques. However, our results from NMR and XPS experiments confirm that the major modifications during all the reactions occurred mainly at the surface. This green process opens the way for the easy production of a new class of cellulose derivatives.

Effect of Resin Acid and Hemicelluloses on Alkyl Ketene Dimer Sizing

Hydrophobisation treatment or sizing is conducted to limit the penetration of water or other liquids into papers, mainly for printing and writing or converting purposes. Internal sizing can be obtained through the addition of alkyl ketene dimer (AKD) into the pulp suspension. It is well known that AKD sizing efficiency depends on process parameters such as pulp grade, dissolved and colloidal substances, and paper drying and storage conditions, but the mechanisms involved are not totally understood. This study focused on the effect of wood extractives on sizing efficiency. First, a thermomechanical pulp (TMP) was used before and after extraction with various solvents and its response to sizing was evaluated. Then, dehydroabietic acid (DH) and hemicelluloses were added to a bleached kraft pulp (BKP) and their effect on sizing, alone or with the coupled action of calcium ions, was studied. The results obtained confirmed that TMP is more difficult to size than BKP and that extraction performed on TMP allows retaining an acceptable sizing level. DH and hemicelluloses impair AKD sizing efficiency and they decrease both retention and reaction of AKD particles onto the fibres. Finally, calcium ions, when alone, may negatively impact AKD retention, but they prevent in certain conditions the detrimental action of DH and xylan.

INFLUENCE OF COMPLEX FIBROUS MEDIA COMPOSITION ON THEIR PERFORMANCES FOR VOC AND PARTICLE REMOVAL

Amongst atmospheric pollutants, two major types can be distinguished: airborne particles such as dust, and gaseous compounds such as Volatile Organic Compounds (VOCs). Fibrous filters are commonly used to remove particles while activated carbon beds trap VOCs. In order to obtain a single-stage device as efficient at collecting particles with a size less than 10 μm (PM10) as removing VOCs, prototype fibrous media containing activated carbon fibers (ACF) associated with cellulose fibers (CF), which are non-adsorptive, have been developed. The influence of ACF ratio and the degree of beating of CF on porous structure, mechanical strength and treatment performances of the medium was studied. Experimental results show that an increase in ACF mass ratio increases the inter-fiber porosity and overall adsorption capacity (the intrinsic adsorption capacity of ACF remains constant whatever the composition), but decreases the mechanical strength and particle collection efficiency of the medium. Moreover, an increase in the beating of CF enhances the mechanical strength of the medium and its particle collection efficiency, but decreases its porosity and has no effect on adsorption capacity. Consequently, a medium containing 50 % ACF associated with CF with a low degree of beating (16 °SR) presents the best performance for combined filtration.

A New Way to Produce Cellobiose Carbonates Using Green Chemistry.

The preparation of cellulose derivatives using green (i.e., environmentally friendly) reagents would improve sustainability and reduce concerns arising from the use of non-green reagents. The objective of this work was to prepare cellobiose carbonate using a green reagent, dimethyl carbonate. The carbonation reaction was carried out in the presence of ethanolic potassium hydroxide solution and dimethyl carbonate for 6 h at a range of temperatures (25-70 °C). A cellobiose derivative was successfully prepared with a recovered yield of more than 70 % and characterized by FTIR and NMR spectroscopy techniques. The presence of a grafted disaccharide with a degree of substitution higher than 2 was determined by (13) C NMR analysis. The spectra of the prepared cellobiose carbonate exhibited peaks that were associated with cellulose molecules (C1 -C6 ) and corresponded to carbonate functions at around 159.4 ppm.

Analysis of the Strain and Stress Fields of Cardboard Box during Compression by 3D Digital Image Correlation

Corrugated boards with small flutes appear as good alternatives to replace packaging folding boards or plastic materials due their small thickness, possibility of easy recycling and biodegradability. Boxes made up of these materials have to withstand significant compressive loading conditions during transport and storage. In order to evaluate their structural performance, the box compression test is the most currently performed experiment. It consists in compressing an empty container between two parallel plates at constant velocity. Usually it is observed that buckling phenomena are localized in the box panels, which bulge out during compression [1]. At the maximum recorded compression force, the deformation localises around the box corners where creases nucleate and propagate. This maximum force is defined as the quasi-static compression strength of the box. The prediction of such strength is the main topic of interest of past and current research works. For example, the box compression behaviour of boxes was studied by Mc Kee et al. [2] and Urbanik [3], who defined semi-empirical formula to predict the box compression strength, as well as by Beldie et al. [4] and Biancolini et al. [5] by finite element simulations. But comparisons of these models with experimental results remain rather scarce and limited.

RETENTION OF CATIONIC STARCH ONTO CELLULOSE FIBRES

Three methods of cationic starch titration were used to quantify its retention on cellulose fibres, namely: (i) the complexation of CS with iodine and measurement of the absorbency of the ensuing blue solution by UV‐vis spectroscopy; (ii) hydrolysis of the starch macromolecules followed by the conversion of the resulting sugars to furan‐based molecules and quantifying the ensuing mixture by measuring their absorbance at a Ι of 490 nm, using the same technique as previous one and; finally (iii) hydrolysis of starch macromolecules by trifluoro‐acetic acid and quantification of the sugars in the resulting hydrolysates by high performance liquid chromatography. The three methods were found to give similar results within the range of CS addition from 0 to 50 mg per g of cellulose fibres.