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Chemical modification of wood by mixed anhydrides. Etude de la modification chimique du bois par des anhydrides mixtes.

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Niveau: Supérieur, Doctorat, Bac+8
THÈSE En vue de l'obtention du DOCTORAT DE L'UNIVERSITÉ DE TOULOUSE Délivré par l'Institut National Polytechnique de Toulouse Discipline ou spécialité : Sciences des Agroressources JURY M. James CLARK (Professeur, The University of York, UK, Rapporteur) M. Alessandro GANDINI (Professeur, Universidade de Aveiro, Portugal, Rapporteur) Mlle Elisabeth BORREDON (Professeur, Institut National Polytechnique de Toulouse) M. Yves CHAUVIN (Membre de l'Académie des Sciences) M. Stéphane GRELIER (Professeur, Université de Bordeaux) Mlle Silham EL KASMI (Responsable R&D LAPEYRE) M. André MERLIN (Professeur, Université de Nancy) M. Carlos VACA GARCIA (Professeur, Institut National Polytechnique de Toulouse) Ecole doctorale : Sciences de la Matière Unité de recherche : Laboratoire de Chimie Agro-industrielle (UMR 1010 INRA/INP-ENSIACET) Directeur de Thèse : Professeur Elisabeth BORREDON Codirecteur de Thèse : Professeur Carlos VACA GARCIA Présentée et soutenue par Jérôme Peydecastaing Le 26 novembre 2008 Titre : Chemical modification of wood by mixed anhydrides. Etude de la modification chimique du bois par des anhydrides mixtes.

  • has been

  • pilot treatment

  • been consumed

  • borredon codirecteur de thèse

  • growth local species

  • fatty cellulose

  • has lead

  • anhydrides mixtes


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Publié par
Publié le 01 novembre 2008
Nombre de lectures 52
Langue Français
Poids de l'ouvrage 5 Mo











THÈSE


En vue de l'obtention du

DOCTORAT DE L’UNIVERSITÉ DE TOULOUSE DOCTORAT DE L’UNIVERSITÉ DE TOULOUSE

Délivré par l’Institut National Polytechnique de Toulouse
Discipline ou spécialité : Sciences des Agroressources
Présentée et soutenue par Jérôme Peydecastaing
Le 26 novembre 2008

Titre : Chemical modification of wood by mixed anhydrides.
Etude de la modification chimique du bois par des anhydrides mixtes.


JURY

M. James CLARK (Professeur, The University of York, UK, Rapporteur)
M. Alessandro GANDINI (Professeur, Universidade de Aveiro, Portugal, Rapporteur)
Mlle Elisabeth BORREDON (Professeur, Institut National Polytechnique de Toulouse)
M. Yves CHAUVIN (Membre de l’Académie des Sciences)
M. Stéphane GRELIER (Professeur, Université de Bordeaux)
Mlle Silham EL KASMI (Responsable R&D LAPEYRE)
M. André MERLIN (Professeur, Université de Nancy)
M. Carlos VACA GARCIA (Professeur, Institut National Polytechnique de Toulouse)


Ecole doctorale : Sciences de la Matière
Unité de recherche : Laboratoire de Chimie Agro-industrielle (UMR 1010 INRA/INP-ENSIACET)
Directeur de Thèse : Professeur Elisabeth BORREDON
Codirecteur de Thèse : Professeur Carlos VACA GARCIA
General summary
Foreword ................................................................................................... 5
CHAPTER 1: The characteristics and the durability of wood
1.1 Introduction ..................................................................................................................... 9
1.2 Generalities ..................................................................................................................... 9
1.3 The wood structure ....................................................................................................... 13
1.4 The properties of wood ................................................................................................. 23
1.5 Current strategies to increase wood stability ................................................................ 34
1.6 Conclusions .................................................................................................................... 58
CHAPTER 2: Acetic-fatty anhydrides analysis and synthesis
2.1. Introduction ................................................................................................................... 68
2.2. Quantitative analysis of mixtures of various linear anhydrides and carboxylic acids .... 69
2.3. Consecutive reactions in an oleic acid and acetic anhydride reaction medium ............ 79
2.4. Conclusions .................................................................................................................... 93
CHAPTER 3: Study of the reactivity of mixed anhydrides toward cellulosics
3.1 Introduction ................................................................................................................... 97
3.2 Accurate determination of the DS of long chain cellulose esters (LCCE) ....................... 99
3.3 Mixed acetic-fatty cellulose esters. Part I. Synthesis ................................................... 115
3.4 Mixed acetic-fatty cellulose esters. Part II. Hydrophobicity ........................................ 133
3.5 Mixed acylation of Scots pine sawdust and impact on hydrophobicity ....................... 151
3.6 Conclusions .................................................................................................................. 175
CHAPTER 4: Influence of the treatment conditions on wood properties
4.1 Introduction... 179
4.2 Methodology 180
4.3 Swelling and specific gravity ........................................................................................ 181
4.4 Mechanical properties ................................................................................................. 187
4.5 Dimensional stability ................................................................................................... 195
4.6 Scanning electron microscopy ..................................................................................... 206
4.7 Surface color characteristics ........................................................................................ 208
4.8 The Wood Protect® pilot treatment ............................................................................ 212
4.9 Conclusions .................................................................................................................. 221
General conclusion .................................................................................. 225
Scientific production 2005-2008 ............................................................... 231 Foreword
The industrial era, that has begun two centuries ago, participated in the
frenetic consumption of fossil and renewable resources. In less than two
hundred years of industrial development, about 50% of the fossil resources have
been consumed. Renewable resources which the mains fields of applications are
energy, food, pharmaceutics, textile and raw material in the construction
industry are also concerned due to an increase consumption caused by a
multiplication of the population by four in less than one century.
Wood as a raw material is also concerned. A global deforestation of about
13 millions of hectares has been observed in 2005 by the Food and Agriculture
Organization of the United Nations (FAO). In the past, naturally durable local
wood species were traditionally used in the construction. But the increasing
consumption of these species that present slow growth has lead to consider
them as non renewable. Durable species have then been imported from the
fantastic resources that are the tropical forests leading to an ecological disaster.
That is why biocide treatments such as CCA and creosotes have been developed
to give to fast growth local species an acceptable durability to be use as lumber.
Nevertheless the toxicity of such treatments has lead to restrict or prohibit their
uses by application of new legislations such as the biocides directive.
A need for developing new wood treatment has therefore become urgent to
replace biocides. Wood modification has been initiated since the 1950’s and
encounter an increased interest in last decade. The main purposes of wood
modification are to increase durability by mean of increasing biological
resistance and to enhance wood properties such as dimensional stability and
photostability to respect the specifications of the wood industry and particularly
the one working on joineries.
The main objective of this dissertation will be to present the investigations
made to develop a new wood treatment based on the chemical modification of
wood. This work has been realized in collaboration with a French company
named LAPEYRE, filial of the SAINT-GOBAIN group. LAPEYRE is a joinery
maker which priorities and interest in this work has been to develop a treatment
able to give high dimensional stability to wood. The investigations were carried out in the French Laboratory of Agro-
industrial Chemistry (LCA) located in Toulouse under the direction of the
manageress of the laboratory, Professor Elisabeth Borredon as well as her
colleague, Professor Carlos Vaca-Garcia.
The treatment deals with chemical modification of wood by mixed acetic-
fatty anhydrides. The process developed during this research allowed to file
three patents, one in 2003 under the number WO2003084723 and two in 2007
under the numbers WO2007141445 and WO2007141444. These applications
found an industrial interest and have been commercialized since 2006 under the
®name of Wood Protect .
Four chapters compose this manuscript.
In the first one, an overview of the chemistry of wood and its preservation
will be presented.
The second chapter is composed of two published peer-reviewed articles;
one dealing with the development of an analytical technique to analyze mixed
anhydrides and the other one on the kinetic and thermodynamic study of their
synthesis.
Chapter three is compiling four articles. The first one describes an
analytical method to determine de degree of substitution of cellulose esters, the
second and the third one describe the esterification reaction on cellulose and the
hydrophobic properties obtained. The fourth paper explains the changes of
reactivity occurred when passing from cellulose to a lignocellulosics substrate:
wood sawdust.
Finally, chapter four presents the treatment of wood blocks at both
laboratory and pilot scales. The dimensional stability, the mechanical
properties, as well as weathering and biological protection are discussed.
Each of these chapters will be accompanied by an introduction and a
conclusion in order to facilitate the understanding of the running of the
investigations. 1 CHAPTER 1
The characteristics and the durability of wood

CONTENTS
1.1 Introduction .......................................................................................... 9
1.2 Generalities ........................................................................................... 9
1.2.1 Wood: a renewable resource .............................................................................. 9
1.2.2 The European and French forest ....................................................................... 10
1.3 The wood structure ............................................................................. 13
1.3.1 Hierarchical structure of wood .......................................................................... 13
1.3.1.1 Cross section of a tree............................................................................... 13
1.3.1.2 Structural differences between softwoods and hardwoods ..................... 15
1.3.1.3 The cell wall of wood ................................................................................ 16
1.3.2 The chemical components of wood .................................................................. 17
1.3.2.1 Cellulose .................................................................................................... 17
1.3.2.2 Hemicelluloses .......................................................................................... 18
1.3.2.3 Lignin ......................................................................................................... 19
1.3.2.4 Other macromolecules ............................................................................. 21
1.3.2.5 Extractives ................................................................................................. 22
1.4 The properties of wood ....................................................................... 23
1.4.1 Interactions with water ..................................................................................... 23
1.4.1.1 Equilibrium moisture content ................................................................... 23
1.4.1.2 The fiber saturation point ......................................................................... 24
1.4.1.3 Swelling and shrinking .............................................................................. 24
1.4.1.4 Hydrophobicity and Water repellency ...................................................... 25
1.4.2 Mechanical properties....................................................................................... 28
1.4.3 Thermal properties and photostability ............................................................. 30
1.4.4 Biological properties .......................................................................................... 31
1.4.4.1 Biological degradations ............................................................................. 31 Chapter 1. The characteristics and the durability of wood


1.4.4.2 Use classes (formerly risk classes) .............................................................33
1.5 Current strategies to increase wood stability ........................................34
1.5.1 Biocides ..............................................................................................................35
1.5.1.1 Old generation of biocides ........................................................................35
1.5.1.2 Legislation .................................................................................................37
1.5.1.3 New generation of biocides ......................................................................39
1.5.2 Bulk-effect preservatives ...................................................................................40
1.5.2.1 Formaldehyde based resins 40
1.5.2.2 Dimethyloldihydroxyethyleneurea (DMDHEU) .........................................41
1.5.2.3 Furfurylation ..............................................................................................42
1.5.2.4 Other treatments ......................................................................................43
1.5.3 Pyrolitic treatments ...........................................................................................46
1.5.4 Oleothermal treatments ....................................................................................47
1.5.5 Chemical modification of wood .........................................................................48
1.5.5.1 Reaction with acid chlorides .....................................................................49
1.5.5.2 Esterification with carboxylic acids ...........................................................49
1.5.5.3 Reaction with ketene ................................................................................50
1.5.5.4 Reaction with aldehydes ...........................................................................50
1.5.5.5 Reaction with isocyanates 51
1.5.5.6 Reaction with epoxides .............................................................................52
1.5.5.7 Cyanoethylation ........................................................................................52
1.5.5.8 Reaction with alkyl halide .........................................................................53
1.5.5.9 Reaction with β-propiolactone ..................................................................53
1.5.5.10 Reaction with cyclic anhydrides ................................................................54
1.5.5.11 Reaction with acyclic anhydrides ..............................................................55
1.6 Conclusions .........................................................................................58
References ..................................................................................................60




Peydecastaing 2008 8
Chapter 1. The characteristics and the durability of wood


1.1 Introduction
Making an extensive description of wood is a tough and long exercise. Indeed,
wood is the main source of cellulose, the most abundant biopolymer on Earth. Many
studies have been carried out on i ts formation, its diversity, its properties, its us es,
and its durability. In the framework of this dissertation , we cannot afford to go into
deep detail of all these subjects. Consequently, we will voluntarily limit to make an
introduction to wood structure and to present the techniques to modify woodto
improve its properties. We will start however with an introduction tow ood as a
renewable r esource a nd t he f orest pr oduction i n Europe a nd FThirs ance.
bibliographical review can be completed by all the comprehensive books we have
1-13consulted to compose this report .
1.2 Generalities
1.2.1 Wood: a renewable resource
Achieving solutions to environmental problems and limited fossil fuel resources
requires long-term potential actions for sustainable development. In this regard,
renewable resources appear to be one of the most efficient and effective solutions. A
gradual shift from fossil fuels to renewabl enee rgy sources seems to be the only
alternative. Unlike fossil fuels, a renewable resource can have a sustainable yield.
A na tural resource is qua lified as renewable if it is r eplenished by na tural
processes at a rate equal or faster than its rate of consumption by humans. Resources
such as solar radiation, tides, and winds re aperpetual resources that are not i n
14danger of being used in excess because of their long-term availability .
Oxygen, water, a ndphot osynthetic biomass such a s wood for i nstance can
become non-renewable r esources i f they ar e used at a r ate gr eater t han the
environment's capacity to form them.
Timber, which can be harvested sustainably at a constant rate without depleting
the existing resource pool , is a uni que and renewable materi althat has been and
remains an important substance throughout history because of its unique and useful
properties. It is not only renewable, but also recyclable and biodegradable.


Peydecastaing 2008 9
Chapter 1. The characteristics and the durability of wood


1.2.2 The European and French forest
The European region is covered with temperate or boreal forests over 37% of its
14area . The number of species in Europe is estimated at 8 000 from the 50 000 in the
world. The European fores tis largely of human creation, through theim portant
reforestation of the last 150 years that followed the extensive exploitation of forests
over previous centuries in this densely populated continent.We gr ow more trees in
Europe t han w e f ell, t hus creating a n i ncrease i n f orest a cross Europe by t he
15equivalent of 25 ha per hour .
The ecological zones of Europe range from subtropical to polar types. Countries
with the richest forest in Europe are Finland and Sweden (Figure 1.1). The said cool
temperate moist forest zone covers much of Europe, and is the most exploited. It is
composed mainly of needle-leaved trees (coniferous).

16Figure 1.1 Forest cover (%) of European countries in 2005
17
In 1830, France wooded surface was between 8.9 and 9.5 millions of hectares .
Since then, growth has been constant. The French forests surface reaches now 15.5
millions of hectares covering 28% of the country’s areTahe. y mostly belong to
private owners. Since 1980, thea nnual expansion recorded by the National Forest
Inventory (NFI) is approximately 68 000 ha.


Peydecastaing 2008 10