December 21, 2012 - Fluid Mechanics, Energy, Processes Ph.D. title Modeling and simulation of the recovery workshop in a kraft mill. Supervision Gérard MORTHA, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Martine RUEFF, Research Engineer, Grenoble INP-Pagora / LGP2 Abstract Chemical recovery at the kraft mill is the process whereby the valuable inorganic elements are extracted from spent kraft liquors and regenerated under their form effective to the cooking of the wood and energy is produced from the dissolved organic fraction. Many unit operations are involved and sometimes insufficiently described in terms of chemical engineering and thermodynamics. In the general framework of the conversion of kraft pulp mills into wood biorefineries, this thesis aims at developing mathematical models of the overall kraft recovery process for implementation in a decision tool. A comprehensive literature review was made regarding the models of the unit operations and the properties of the constituents. A database of the thermodynamic, physical and chemical properties of the constituents was created. The existing models were analysed and a new modelling approach for the evaporators was developed. The models were implemented in a C/C++ library which was called in an object oriented simulation platform using the Modelica language (OpenModelica/Dymola) and were validated against literature results. Several simulation scenarii have put forward the main issues for global energy gains and the directions for possible improvements of some operations. More particularly the high refinement of the evaporator model in terms of thermodynamics and chemical engineering, above the published literature on the topic, opens novel perspectives in terms of strategy for process control of the evaporator train. Other members of the jury Patrice NORTIER, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Xavier JOULIA, Professor, ENSIACET (Toulouse) ♦♦ Éric SCHAER, Professor, ENSIC (Nancy) ♦♦ Thierry MAYADE, Director R&D, Munksjö (Sweden)
December 20, 2012 - Materials, Mechanical, Civil Engineering, Électrochimique[Thesis online] Ph.D. title Development of new packaging materials based on micro- and nano-fibrillated cellulose. Supervision Alain DUFRESNE, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Florence GIRARD, Research Engineer, Centre Technique du Papier Abstract The micro- and nanofibrillated cellulose (MFC/NFC) are nanomaterials from renewable resource with a high interest and partly for the packaging development. MFC combined both interesting properties (high tensile strength, good barrier to oxygen and grease, good transparency) and the advantages of natural cellulose source. The objective of this thesis was to develop a barrier packaging board based on MFC/NFC by coating processes. Firstly, the study focussed on the characterisation of the MFC suspensions, on the manufacturing of MFC self-standing films and on the determination of their properties. Secondly, the development of MFC based composites was studied as model films. The last part was devoted to the introduction of MFC in coating colours in order to develop a barrier layer at the board surface. Trials at pilot scale demonstrated the industrial feasibility of this product. The potential of the use of MFC/NFC was demonstrated to be used as a drying additive and as a main component of barrier layer. Other members of the jury Hamid KADDAMI, Professor, Université Cadi Ayyad (Marrakech, Maroc) ♦♦ Nathalie GONTARD, Research Director, INRA Montpellier ♦♦ Marie-Pierre LABORIE, Professor, University of Freiburg (Germany) ♦♦ Noël CARTIER, Head of R&D Projects, Ahlstrom
December 17, 2012 - Fluid Mechanics, Energy, Processes[Thesis online] Ph.D. title Pure cellulose production from kraft pulp by an environmentally friendly process using catalysed hydrogen peroxide. Supervision Dominique LACHENAL, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Nathalie MARLIN, Associate Professor, Grenoble INP-Pagora / LGP2 Abstract The aim of the thesis was to develop a process for "green" pure cellulose production obtained from hardwood kraft pulp. The proposed treatment includes a first step of hot-acidolysis for reducing the content of hexenuronic acids and transition metallic cations (Cu, Fe, Mn) in the pulp. The second step is the pulp delignification using alkaline hydrogen peroxide catalyzed by the Cu-phenanthroline complex. The presence of the catalyst improves the delignification efficiency since alcohol functions carried by the lignin macromolecule in position of the aliphatic chain are selectively oxidized. To eliminate residual hemicelluloses, it is proposed to carry out a cold caustic extraction. Finally, the last unsaturated impurities are degraded by pulp ozonation. After the full sequence of treatments, the chemical composition of the produced cellulose is similar to that of market pure celluloses (for textile or plastic uses), in line with the objectives. The addition of the catalyst reduces the polymerization degree of cellulose. It thus makes it possible to adjust the value of the cellulose DP according to the targeted applications. Other members of the jury Monika EK, Professor, KTH Royal Institute of Technology (Sweden) ♦♦ Rogério SIMOES, Professor, Universidade da Beira Interior (Portugal) ♦♦ Vanessa DURRIEU, Associate Professor, ENSIACET (Toulouse) ♦♦ Alain DERONZIER, Research Director, Université Joseph Fourier (Grenoble)
December 12, 2012 - Fluid Mechanics, Energy, Processes[Thesis online] Ph.D. title Design of self-adhesive labels by microencapsulation adhesive. Supervision Naceur BELGACEM, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Didier CHAUSSY, Professor, Grenoble INP-Pagora / LGP2 Abstract The main objective of this study is to prepare innovative silicone liner-free labels. It can be achieved by the adhesive self protection', thanks to its incorporation into microcapsules. This allows the preparation of dry labels' gluing under the application of a pressure, which induces the rupture of the microcapsules, thus releasing the core material, a pressure sensitive adhesive. The first step was to analyse 3 water-based PSA in view of their encapsulation. Then, the most suitable adhesive was microencapsulated by coacervation (using biopolymer as shell) and by in situ polymerisation. Two other encapsulation processes (spray-cooling and spray-drying), were also carried out and were compared with the 2 former processes. Coating colour formulations were prepared with spray-cooling microcapsules (the most adhesive ones). Coating trials were carried out by blade coating, and by screen printing. Compatibility between microcapsules and the label making process, using a flexographic printing press, was determined. Finally, the mains characteristics of the prepared innovative products (adhesion, application pressure) were compared to industrial self-adhesive homologues, and found that they could be suitable for the preparation of silicon liner-free envelops and stamps. Other members of the jury Stéphanie BRIANÇON, Professor, LAGEP (Villeurbanne) ♦♦ Roberta BONGIOVANNI, Associate Professor, Politecnico di Torino (Italy) ♦♦ Salaheddine SKALI-LAMI, Associate Professor, LEMTA (Nancy) ♦♦ Gilles BRUAS, Director, Papeterie Gerex (Voreppe) ♦♦ Bernard PINEAUX, Research Engineer, Grenoble INP-Pagora / LGP2
November 22, 2012 - Materials, Mechanical, Civil Engineering, Electrochemistry[Thesis online] Ph.D. title Functionalization and surface modification of nanofibrillated cellulose. Supervision Naceur BELGACEM, Professor, Julien BRAS ♦♦ Julien BRAS, Associate Professor, Grenoble INP-Pagora / LGP2 Abstract Since last decades, nanocelluloses know a strong interest and they are the subject of many studies led by industrials and/or academic consortia. This study is a part of the European project SUNPAP for the industrialization of nanofibrillated cellulose (NFC). This thesis is the state of new methods for the chemical surface modification of NFC with a view of green chemistry. Several strategies have been developed such as the use of ionic liquids as reaction solvents (described as green solvents) or the use of an aqueous nanoemulsion in order to graft the surface of NFCs. Thus, the treated substrates were then used in various applications. Also, bionanocomposites were produced, the impact of the introduction of NFC (modified or not) in paper sheets has also been studied. A study on the antibacterial properties and biodegradability of modified NFC is also proposed. Several characterizations of neat and modified NFC were performed. Powerful and innovative techniques have been used to characterize these substrates such as XPS (X-ray Photoelectron Spectroscopy) or SIMS (Secondary Ion Mass Spectrometry). All these chemical modifications, applications and characterizations are offered promising prospects in the world of nanocelluloses. Other members of the jury Etienne FLEURY, Professor, INSA de Lyon ♦♦ Monika ÖSTERBERG, Associate Professor, Aalto University (Finland) ♦♦ Stéphane GRELIER, Professor, Université Bordeaux 1 ♦♦ Noël CARTIER, Senior Scientist, Ahlstrom.
October 30, 2012 - Fluid Mechanics, Energy, Processes[Thesis online] Ph.D. title Contribution to the development of a photocatalytic paper. Application to the reduction of Volatile Organic Compounds Supervision Pierre-Xavier THIVEL, Associate Professor, Université Joseph Fourier (Grenoble) Résumé The objective is to elaborate a based-paper titanium/silica photocatalysis for on stream flue gas depollution (volatile organic compounds) stemming from processes of printing. The volatile organic compound used in this study is the ethanol. Particles of hollow silica were synthesized and used as a support for nanoparticles of titanium dioxide, which were elaborated by sol-gel method. A continuous reactor was designed and used to treat the polluted gaseous flow. The ethanol passes through the photocatalytic paper irradiated by a UV lamp. Several photocatalytics papers were elaborated and characterized by several techniques (MEB, Spectroscopy Raman, DRX). A modeling of the reactor and the support (photocatalytic paper) was developed and proposed. This modeling integrates the Langmuir - Hinshelwood kinetic and the variation of the intensity with position in layer's paper using the Kublka-Munk model. Other members of the jury Jean-Claude ROUX, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Laurence LE COQ, Professor, École des Mines de Nantes ♦♦ Jean-Michel GUILLOT, Professor, École des Mines d'Alès ♦♦ Abdelkrim BOUZAZA, Associate Professor, ENS Chimie de Rennes ♦♦ Nicolas SERGENT, Associate Professor, Grenoble INP-Phelma
October 26, 2012 - Materials, Mechanical, Civil Engineering, Electrochemistry[Thesis online] Ph.D. title Elaboration of Li-ion batteries using cellulose fibers and papermaking techniques. Supervision Davide BENEVENTI, CNRS Researcher, LGP2 ♦♦ Didier CHAUSSY, Professor, Grenoble INP-Pagora / LGP2 - Claudio GERBALDI, Associate Professor, Politecnico di Torino (Italy). Abstract This work investigates the production of low cost, low environmental impact, easily up-scalable and recyclable cellulose-based Li-ion batteries. Two main research approaches were explored. At first, microfibrillated cellulose was used for the production of paper-like anodes by means of a water-based casting process. Then, a papermaking approach was adopted and the majority of the experimental work was focused on the use of cellulose fibers for the production of paper-electrodes (i.e. anodes and cathodes) and paper-separators by means of a water-based filtration process. The prepared electrodes are easy to handle and self-standing with good electrochemical characteristics, comparable with that of standard synthetic polymer-bonded electrodes. Other members of the jury Nadia EL KISSI, Research Director CNRS, Université Joseph Fourier (Grenoble) ♦♦ Lars WAGBERG, Professor, KTH Royal Institute of Technology (Sweden) ♦♦ Bernard LESTRIEZ, Associate Professor, Université de Nantes ♦♦ Hatem FESSI, Professor, Université Claude Bernard Lyon 1.
October 26, 2012 - Materials, Mechanical, Civil Engineering, Electrochemistry[Thesis online] Ph.D. title Manufacture of membrane-electrode assembly of fuel cells by printing processes. Supervision Anne BLAYO, Lecturer Researcher, Grenoble INP-Pagora / LGP2 ♦♦ Didier CHAUSSY, Professor, Grenoble INP-Pagora / LGP2 Abstract In a context of fossil fuel shortage and hydrocarbon emission reduction, fuel cells are a promising solution for energy production. However, the cost of the energy they produce remains too expensive to be competitive and the conventional manufacturing processes used limit the scaling up of the production. The core of Proton Exchange Membrane Fuel Cells (PEMFCs) is a stack composed of five constituents, in which the proton exchange membrane and the two gas diffusion layers can be considered as printing substrates, and the two catalyst layers can be printed by continuous printing processes. This work demonstrated the relevance of flexography for manufacturing fuel cell components. It allows large production with low waste of expensive elements. Despite of the poor printability of the substrates, the catalyst layers printed by flexography reached similar electrochemical properties than those made by conventional processes. Other members of the jury Yann BULTEL, Professor, Grenoble INP ♦♦ Reinhard BAUMANN, Professor, Chemnitz University of Technology (Germany) ♦♦ François LAPICQUE, Research Director CNRS, Université de Lorraine
September 28, 2012 - Fluid Mechanics, Energy, Processes[Thesis online] Ph.D. title Study of the mechanical behavior of recycled fibers. Applications to papers and paperboards. Supervision Jean-Francis BLOCH, Associate Professor, Grenoble INP-Pagora / LGP2 ♦♦ Raphaël PASSAS, Research Engineer, Grenoble INP-Pagora / LGP2 Abstract By nowadays, the environmental politic is important: the deforestation or the stress on the wood market contribute to the increased interest to improve the recovered rate in papers. Particularly, high value papers constitute a specific target due to their high amount of virgin fibres. The aim of this work was to characterise the modifications of morphological and physical properties occurring during drying and rewetting cycles. To reach this aim, experimental technics have been revisited or developed like the inverse size exclusion chromatography, the atomic force microscopy, the environmental scanning electron microscopy and the micro-tomography. This experimental study showed that the main morphological changes occur during the first cycle. Furthermore, delamination and densification of cell wall fibres were highlighted. Evolutions of the mechanical behavior of handsheets and their 3D structures were analysed in function of the proportion and the quality (number of cycles) of fibres. This work demonstrates the potential of valorisation of the recycled fibres in the paper area, especially for high value papers. Other members of the jury Christian GEINDREAU, Professor, Université Joseph Fourier (Grenoble) ♦♦ Ana Paula COSTA, Professor, Universidade da Beira Interior (Portugal) ♦♦ William SAMPSON, Professor, University of Manchester (UK)
September 27, 2012 - Fluid Mechanics, Energy, Processes[Thesis online] Ph.D. title Advanced cellulose composites, preparation and properties. Supervision Alain DUFRESNE, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Mohamed Adel YOUSEF, Professor, Helwan University, Egypt Abstract The present study deals with utilization of Egyptian bagasse in both conventional and non-conventional fields. The conventional application is devoted to papermaking, where bagasse pulp is the most appropriate pulp for this purpose due to the suitability of fiber length and high cellulose and hemicellulose contents. The non-conventional application is dedicated to the preparation of cellulosic derivatives having liquid crystalline properties.The first approach deals with using modified soy protein isolate (SPI) as binder for cellulosic fibers in paper composites. Modification of SPI was carried out through i) denaturation with urea and NaOH. ii) addition of acrylamide to the denatured SPI. iii) changing pH of SPI. These types of modification were used to improve the adhesion properties of SPI. Pronounced mechanical and physical properties of paper sheets filled with 0.5, 2.5 or 5% denatured SPI was obtained upon using 2.5%. The optimum condition of SPI addition was used in ii and iii modifications. The additional effect of acrylamide on SPI was pronounced where the mechanical and physical properties were enhanced. Correlation between the mechanical and physical properties of paper sheets with the pH of SPI was studied. The used pHs were 3, 5, 7 and 10.The results showed that the maximum breaking length was obtainedAbstract - xix -at the isoelectric point of SPI at pH 5 (at the isoelectric point (IEP) the number of positive and negative charges on the polyion is the same, giving a net charge of zero) and it began to decrease when the pH is increased to pH 10. Both the burst index and the tear index showed parallel trends.In the second approach, a series of 4- alkyoxybenzoyloxypropyl cellulose (ABPC-n) samples were synthesized via the esterification of hydroxypropyl cellulose (HPC) with 4-alkoxybenzoic acid bearing alkoxy chain with different lengths. On the other hand, cellulose was isolated in pure form from Egyptian bagasse pulp. Hydroxypropylation was then conducted on the isolated cellulose. 4-alkyoxybenzoyloxypropyl cellulose (ABPC-m) samples were synthesized via the esterification of the latter product with the same acid, bearing 2, 10 and 12 carbon atoms in the side chain and characterized.The molecular structure of both esters (ABPC-n and ABPC-m) was confirmed by Fourier transform infrared (FT-IR) and 1H NMR spectroscopy. The liquid crystalline (LC) phases and transition behaviors were investigated using polarized light microscopy (PLM), and differential scanning calorimetry (DSC), respectively. The lyotropic behavior of the derivatives was investigated in DMA solutions using PLM andAbstract - xx -the critical concentration was firstly determined via refractive index measurements. Other members of the jury Aid KHALIL, Professor, Helwan University, Egypt ♦♦ Magdi NAOUM, Professor, Cairo University, Egypt ♦♦ Étienne FLEURY, Professor, INSA Lyon, France ♦♦ Nahla EL-WAKIL, Professor, National Research Center, Egypt ♦♦ Ali SARHAN, Professor, Mansoura University, Egypt
September 7, 2012 - Fluid Mechanics, Energy, Processes[Thesis online] Ph.D. title Study of the impact of hemicellulose extraction from wood on cellulose fibres and ethanol production as part of a lignocellulosic biorefinery . Supervision Christine CHIRAT, Associate Professor, Grenoble INP-Pagora / LGP2 ♦♦ Dominique LACHENAL, Professor, Grenoble INP-Pagora / LGP2 Abstract Biofuel revival could be a great opportunity for the chemical pulp industry to widen the range of its products made from wood. This thesis deals with the integration of a softwood hemicellulose extraction step prior to the Kraft pulping process in order to produce both cellulose fibres and bioethanol. In this study the experimental work covers the entirety of the process: from the extraction of more than half of the hemicelluloses from wood either by autohydrolysis or dilute acid hydrolysis to the production of bleached cellulosic fibres as well as ethanol from fermentated wood hydrolyzates. Prehydrolyzed wood and their subsequent pulps stood out by their excellent delignification ability during Kraft cooking and oxygen bleaching. Quantitative analysis of the main constituants of the pulps showed why prehydrolysis leads to decreased Kraft pulp yields (extra lignin loss and hemicelluloses loss including xylans). A range of hypotheses to explain the good delignification ability of prehydrolyzed wood Kraft pulps during oxygen bleaching was narrowed to one by Kraft lignin analysis. The overall results of the hemicellulose extraction prior to Kraft pulping as it has been defined in this study showed that from 100 kg of softwood, 27 to 36 kg of bleached cellulosic fibres and 6 litres of ethanol could be produced. The bleached cellulosic fibres are of great interest for dissolving pulp or cellulose nanocrystals production. Other members of the jury Nicolas BROSSE, Professor, Université de Lorraine ♦♦ Ana Paula DUARTE, Professor, Universidade da Beira Interior (Portugal) ♦♦ Marie-José VILLETTE, Head of R&D, Fibre Excellence R&D Kraft.
July 20, 2012 - Fluid Mechanics, Energy, Processes Ph.D. title Delignifying chemical system based on hydrogen peroxide. Supervision Gérard MORTHA, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Vanessa DURRIEU, Associate Professor, INP Toulouse / LCA Other members of the jury Dominique LACHENAL, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Stéphane GRELIER, Professor, Université de Bordeaux 1 ♦♦ Carlos PASCOAL-NETO, Professor, Universidade de Aveiro (Portugal) ♦♦ Pierre LARNICOL, Business Manager, Arkema
June 14, 2012 - Fluid Mechanics, Energy, Processes Ph.D. title Deinking pulp fractionation: characterization and separation of fines by screening. Supervision François JULIEN SAINT AMAND, Deputy Director R&D, & Benjamin FABRY, Manager Deinking Process, Centre Technique du Papier ♦♦ Raphaël PASSAS, Research Engineer, Grenoble INP-Pagora / LGP2 Abstract Deinking is a key process in a sustainable strategy for papermaking, where the ink contained in the fine fraction (defined as passing a 76µm screen) is eliminated from the fibrous suspension. Fines sub-fractions analysed by a new manual classification method showed that the major contamination of ink occurs in the fraction which passes 11µm openings. Visual analysis of the microscopic images revealed that fibrils are in majority almost ink free whereas flakes from mineral fillers or cellulosic origin have ink deposition with varying coverage. Pulp fractionation is a viable option which opens avenues for separation of fines from pulp and offers opportunity of dedicated treatment to each fraction. Separation of fines by a pressure screening system equipped with a micro-hole screen plate showed a higher selectivity towards the separation of fines into the accepts than conventional slot-screen cylinders. Comprehensive understanding of rotor hydrodynamics helped to understand the capacity constraints and inlet concentration limits. Studies showed that such a micro-hole screen plate is well adapted to rationalize deinking operations, where dedicated treatment on different fractions could be envisaged. The study highlighted that new optimised deinking lines could be envisaged by introducing a specific fractionation technology and that pulp fines can be valorised, with an important impact in future manufacturing concepts as specifically engineered multilayer papers. Other members of the jury Evelyne MAURET, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Harald GROSSMANN, Professor, Technische Universität Dresden (Germany) ♦♦ Paulo FERREIRA, Assistant Professor, Universidade da Coimbra (Portugal) ♦♦ Frédéric VAULOT, Director R&D, Kadant-Lamort (France)
June 13, 2012 - Organic chemistry Ph.D. title Study and use of copper(II) polypyridinic complexes in catalysis of dioxygen delignification of cellulosic pulps. Supervision Alain DERONZIER, Research Director, Université Joseph Fourier (Grenoble) ♦♦ Nathalie MARLIN, Associate Professor, Grenoble INP-Pagora / LGP2 Abstract Dioxygen delignification considerably reduces the operating cost of the bleaching process and decreases the environmental impact of the bleaching effluent. Unfortunately the performance of dioxygen delignification is limited since part of the residual lignin is not reactive toward dioxygen while cellulose depolymerisation occurs. Studies suggested that dioxygen delignification could be improved thanks to the use of catalysts such as copper(II)-phenanthroline type complexes which have shown promising results on delignification efficiency. However cellulose was also more degraded. Different polypyridinyl ligands have been studied in this work, in an attempt to find copper(II) complexes that have more affinity toward lignin and less toward cellulose. Complexes have been characterised by UV/Vis spectroscopy, cyclic volammetry, and they were studied for the catalysed oxidation of various substrates: a non phenolic lignin model compound and lignocellulosic substrates (a model of cellulose, a model of native lignin and an industrial kraft pulp). It has been shown that the nature of the ligand had a significant effect on the catalytic activity of Cu(II) complexes in the oxygen oxidation of the lignin model compound. However, the active complexes only show a limited activity during the delignification of a kraft pulp and oxidize carbohydrates. This lack of selectivity prevents from an industrial application for paper pulp production but may be useful for the design of products with fewer constraints on cellulose polymerization degree. Other members of the jury Alain CASTELLAN, Professor, ENSCBP/IPB (Bordeaux) ♦♦ Joël ALBET, Associate Professor, INP Toulouse ♦♦ Jean-Marie HERRMANN, Research Director, IRCELYON (Lyon 1) ♦♦ Dominique LACHENAL, Professor, Grenoble INP-Pagora / LGP2
June 6, 2012 - Materials, Mechanical, Civil Engineering, Electrochemistry[Thesis online] Ph.D. title Surface modification of cellulose by the organosilanes. Supervision Naceur BELGACEM, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Evelyne MAURET, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Elisa ZENO, Research Engineer, Centre Technique du Papier Abstract This thesis describes the chemical modification of cellulosic fibers by organosilanes. The reactions of silanes bearing various functional groups were carried out in pure aqueous solution and followed in-situ by nuclear magnetic resonance spectrometry. The effect of pH, concentration, and temperature on the reaction kinetics was studied. Aminosilanes could be processed in conditions similar to those commonly used in the papermaking. Furthermore, the adsorption of the most promising grafting agents on model cellulose surfaces was investigated by mean of a quartz crystal microbalance, and the effect of the same parameters was evaluated. This study showed that a good surface coverage is attained rapidly, i.e., within only a few minutes. Then, a slower but continuous adsorption was observed over time. The nature of the interactions between various silanes and cellulose was tested. It was shown that the grafting was successfully performed, thus giving rise to the formation of strong interactions between the adsorbate and the adsorbent. Finally, two types of fibers (softwood and hardwood) were used in order to evaluate the effect of organosilanes on mechanical properties and the softness of paper. The results obtained showed quite modest effects, even though the success of the grafting was assessed on both type of fibers. Other members of the jury Didier LEONARD, Professor, CPE Lyon ♦♦ Antonio PIZZI, Professor, ENSTIB (Nancy) ♦♦ Maria Emília CABRAL AMARAL, Professor, Universidade da Beira Interior (Portugal)
Eder José SIQUEIRA
June 5, 2012 - Fluid Mechanics, Energy, Processes[Thesis online] Ph.D. title Polyamideamine epichlorohydrin-based papers: mechanisms of wet strength development and paper repulping. Supervision Evelyne MAURET, Professor, Grenoble INP-Pagora / LGP2 ♦♦ Naceur BELGACEM, Professor, Grenoble INP-Pagora / LGP2 Abstract Polyamideamine epichlorohydrin (PAE) resin is a water soluble wet strength additive used for preparing wet strengthened papers (WSP). Even if PAE is largely used in the papermaking industry, there is still a lack of knowledge concerning the cross-linking reactions, the effect of the operating conditions on the properties of the produced papers as well as the recycling of WSP. The first part of this work showed that the main PAE cross-linking reaction occurs by a nucleophilic attack of N atoms in the PAE structure forming 2-propanol bridges between PAE macromolecules. A secondary contribution of ester linkages to the PAE cross-linking resulting from the reaction between carboxylic groups and azetidinium rings was also observed. This reaction is important in the presence of carboxylmethyl cellulose (CMC). However, it can be postulated that ester bond formation has a negligible impact on the wet strength of PAE-based papers because the amount of carboxylic groups present in lignocellulosic fibres is considerably less high than in CMC and the resulting formed ester bonds are hydrolysable. In the second part of this work, the obtained results showed that, when PAE is added to a fibrous suspension (bleached chemical pulp - Eucalyptus), the adsorption, reconformation and/or penetration phenomena reach an apparent equilibrium after 10 min of contact time. An increase of the conductivity of the pulp suspension (from 100 to 3000 S/cm) negatively impacts the strength of the WSP, but for high dosages only (1%). Finally, the degradation of PAE films and PAE-based papers was studied in order to improve the recycling of WSP. For the tested conditions, sodium persulfate is the most effective reagent but the efficiency of the treatment is decreased when coated papers are used. Other members of the jury Ana Paula COSTA, Professor, Universidade da Beira Interior (Portugal) - Marie-Pierre LABORIE, Professor, University of Freiburg (Germany) ♦♦ Jean-Pierre JOLY, Researcher CNRS, Université Henri Poincaré (Nancy) ♦♦ Séverine SCHOTT, Engineer, Ahlstrom LabelPack (Pont-Evêque)
May 3, 2012 - Fluid Mechanics, Energy, Processes[Thesis online] Ph.D. title Printing processes dedicated to the mass production of ceramic based electronic microdevices. Supervision Anne BLAYO, Lecturer Researcher, Grenoble INP-Pagora / LGP2 & Nadège REVERDY-BRUAS, Associate Professor, Grenoble INP-Pagora / LGP2 Abstract This work demonstrates the printing processes potential for manufacturing ceramic based electronic devices. Several printing techniques were studied: screen printing, flexography, rotogravure and inkjet. Ceramic tapes surface properties were characterised: surface pore size, roughness and surface energy. These analyses allowed the selection of the inks raw materials adapted to the substrates and the printing processes. Water-based silver inks were formulated. Inks properties, rheology and surface tension, were analysed and their effect on line properties was investigated. Printed substrates were afterwards sintered. Resistivity values close to that of bulk silver were reached (2 to 12x10-8 Ohm.m). These work novelties are mainly the formulation of water-based environmentally friendly screen printing pastes and the flexography printing of silver inks onto ceramic substrates. This study offers new perspectives for the industrialisation and the mass production of electronic components on flexible ceramic substrates. Other members of the jury Didier CHAUSSY, Professor, Grenoble INP-Pagora / LGP2 - Martine LEJEUNE, Professor, Université de Limoges - Arnaud MAGREZ, Doctor, École Polytechnique Fédérale de Lausanne (Swiss) - Leszek GOLONKA, Professor, Wroclaw University of Technology (Poland) - Stéphane BREDEAU, Doctor, Commissariat à l'Énergie Atomique et aux Énergies Renouvelables
February 14, 2012 - Fluid Mechanics, Energy, Processes Ph.D. title The X-ray microtomography as a tool for solving industrial problems in pulp and paper. Supervision Jean-Francis BLOCH, Associate Professor, Grenoble INP-Pagora / LGP2 - Patrice MANGIN, Professor, Université du Québec à Trois-Rivières (Canada) Abstract The X-ray microtomography can provide useful innovative information for solving current industrial problems. Indeed, to better understand the behavior of a material during its use, we must study its structure on a microscopic scale, that allows the X-ray microtomography. In this thesis, the use of this technique was used to analyze the phenomena of flow and filtration in the pulp and paper. In the first part, flows through forming fabrics were studied by connecting the structure measured by microtomography to the flow simulations and experimental measurements. In the second part, the filtration of mineral fillers through a fibrous mat was tested in order to understand the phenomena occurring during filtration of the formation of the paper. The last part was devoted to the print quality of paper attached to its structure. Other members of the jury Christian GEINDREAU, Professor, Université Joseph Fourier (Grenoble) - Laurence SCHACHER, Professor, ENSISA (Strasbourg) - Dominique THOMAS, Professor, INPL (Nancy) - Martin DUBE, Associate Professor, Université du Québec à Trois-Rivières (Canada) - Pierre DUMONT, Associate Professor, Grenoble INP-Pagora / LGP2 - Sabine ROLLAND DU ROSCOAT, Associate Professor, Université Joseph Fourier (Grenoble)