evelyne mauret

ABSTRACT The complex behaviour of corrugated board packages under compression loading is investigated in this work. Original experimental data are obtained by using a Digital Image Stereocorrelation technique for measuring the displacement and strain fields of the panels’ outer liner of the tested boxes. The stress field is also estimated by accounting for the anisotropic mechanical behaviour of the outer liner, its residual stress state induced by the processing of the corrugated board and the effects of box manufacturing operations and compression. Results show that these fields are extremely heterogeneous on the panels’ surface. Most stressed areas are located along the panels’ edges. The elastic limit of the outer liner is reached quite soon during compression. Box geometry and panel flaps are of primary importance on the observed phenomena. This approach delivers useful information to improve kinematic and constitutive assumptions for buckling and post-buckling models of boxes or thin-walled sandwich structures.Highlights► Investigation of buckling behaviour of corrugated board packages under compression. ► Measurement of displacement and strain fields by Digital Image Stereocorrelation. ► Estimation of stress field accounting for anisotropic mechanical properties. ► Influence of manufacturing, processing, compression and geometry of packages’ panels. ► Highly compressed area located along vertical and horizontal panels’ edges.

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.

Different qualities of CMC were prepared from an agricultural residue (date palm rachis) and a marine waste (Posidonia oceanica). These starting lignocellulosic materials were used as such and after chemical pulping and bleaching. The carboxymethylation reaction was carried out in presence of NaOH (40%) and monochloroacetic acid (ClCH2COOH, MAC), in n-butanol as the reaction solvent. The substitution degrees (DS) of the obtained CMCs varied from 0.67 to 1.62 and between 0.98 and 1.86, for P. oceanica and date palm rachis, respectively. The CP-MAS 13C-NMR spectra of the prepared polyelectrolytes displayed the presence of the main peaks associated with cellulose macromolecules (C1–C6) and that corresponding to carboxyl functions at around 175 ppm. Unfortunately, the peak attributed to methylene groups neighbouring carboxyl moieties are overlapped by C2 and C3, which renders them hardly detectable. Nevertheless, it is worth noting that the CP-MAS 13C-NMR spectra revealed the presence of different signals originating from residual impurities (ca. 27 ppm), such as traces of lignin macromolecules (110–150 ppm) and methyl groups attributed to hemicelluloses. Work is in progress to establish a more efficient purification procedure, in order to have more accurate values of DS.

Four different fractions of phosphogypsum were characterized by several analytical techniques. The size and shape of particles were determined by scanning electron microscopy. Analyses of infrared spectroscopy and X-ray diffraction have shown that these particles are mainly composed of calcium sulfate more or less hydrated. Calcination tests were carried out showed that treatment of these powders at 600°C for one hour increase their initial britghtness to values high enough to be used as a filler in paper.

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 ...