Table of Contents
List of contributing authors ix
1 Introduction of advanced functionalities in laminates for wood-based panels: surface quality evaluation Ana Henriques Cristina Coelho Joao M. Ferra Jorge Manuel Martins Fernao D. Magalhães Luísa Carvalho 1
1.1 The HPL and its manufacture 1
1.1.1 Introduction 1
1.1.2 The raw materials 4
1.1.3 HPL manufacturing process 6
1.2 HPL properties 8
1.2.1 Test methods for HPL characterization 8
1.2.2 HPL specifications 22
1.3 Upgrading HPL characteristics 23
1.3.1 Mar resistance 23
1.3.2 Abrasion resistance 24
1.3.3 Resistance against strong chemicals 24
1.3.4 Weathering resistance 26
1.3.5 Self-healing properties 27
1.3.6 Postformable laminates 28
1.3.7 Dirt repellence 28
1.3.8 Antibacterial action 28
1.3.9 Thermal comfort 29
1.3.10 Phosphorescence 29
2 Activation of natural fibers using physical routes: Applications for composites materials Stephane Molina 33
2.1 Introduction 33
2.1.1 Reinforcements 34
2.1.2 Polymer matrix 35
2.2 Surface activation of cellulosic fibers: Wave and radiation technologies 37
2.2.1 Ultraviolet (UV) technology 37
2.2.2 Plasma technologies 40
2.2.3 Corona technologies 44
2.2.4 High energy radiations technologies 49
2.3 Surface activation of cellulosic fibers: Physico-chemical technologies 53
2.3.1 Ultrasound technologies 53
2.3.2 Solvent technologies 56
2.4 Surface activation of cellulosic fibers: Thermomechanical technologies 56
2.4.1 Steam explosion (SE) technology 56
2.5 Surface activation of cellulosic fibers: Other technologies 62
2.5.1 Steam technologies 62
2.5.2 Carding technologies 63
2.6 Conclusions 65
3 Natural matrix/non wood natural fibers composites A. Pizzi 73
3.1 Comparison with UD fiber-reinforced composites 75
3.2 Water resistance of the composites 76
3.3 Influence of the layers on the composite properties 76
4 Ultrasonic press control and evaluation of wood-based composite panel properties Frank C. Beall Henrique Reis 87
4.1 Introduction 87
4.2 Background 88
4.2.1 Assessment methods 88
4.3 Main focus of this chapter 92
4.3.1 Press control 92
4.3.2 On-line measurement of board properties 96
4.4 Future research directions 97
4.4.1 Press control 97
4.4.2 On-line air coupling 98
4.4.3 Preliminary results from single-sided testing 103
4.5 Conclusions 104
5 Reconstituted composite from crop stalks Xiaozhou Song Yafang Lei Zhangjing Chen 107
5.1 Introduction 107
5.2 Characteristics of crop stalks 108
5.2.1 Cotton stalk 108
5.2.2 Tobacco stalks 111
5.2.3 Soybean stalks 112
5.2.4 Cornstalks 114
5.2.5 Capsicum pepper stalks 115
5.3 The manufacturing process 117
5.3.1 Raw material preparation 119
5.3.2 Stalk softening and combing 119
5.3.3 Crop stalk drying 119
5.3.4 Crop stalk sizing 120
5.3.5 Crop stalk forming 121
5.3.6 Hot pressing 121
5.3.7 End products 122
5.3.8 Properties of the composite 122
5.3.9 Stalk composite appearance and other performance 125
5.4 Curing mechanism of urea-formaldehyde resin in stalk composite 127
5.4.1 Infrared spectroscopy before curing 127
5.4.2 Infrared spectroscopy after curing 128
6 Wood welding without adhesives A. Pizzi 133
6.1 Systems of frictional wood welding 134
6.1.1 Linear vibration welding 134
6.1.2 High speed rotation dowel welding 137
6.1.3 Bamboo welding 139
6.2 Applications of wood welding 140
6.3 Exterior and semiexterior applications 140
6.4 Interior applications 143
7 Surface quality of mechanically processed wood José Reinaldo Moreira da Silva Anna Carolina de Almeida Andrade Jordao Cabral Moulin 147
7.1 General considerations on wood formation 147
7.2 Surface evaluation 153
7.2.1 Quality assessment by feed per tooth (fz) 153
7.2.2 Quality assessment by the depth of the cycloid arc (f) 156
7.2.3 Quality assessment by visual analysis 157
7.2.4 Quality assessment by surface roughness 158
7.2.5 Quality assessment by sunset laser 160
8 Strategies to reduce formaldehyde emissions from wood-based panels: Impact on physico-mechanical properties and machinability Jorge Manuel Martins Cristina Coelho João Pereira Joao Macias Ferra Luísa Carvalho 165
8.1 Strategies to reduce formaldehyde emissions from wood-based panels 166
8.1.1 The concern about formaldehyde and current status 166
8.1.2 Current test methods for determining formaldehyde emissions 167
8.1.3 Formaldehyde emission classes 175
8.1.4 Strategies to reduce formaldehyde emissions from wood-based panels 177
8.2 Impact of formaldehyde-reducing strategies on formaldehyde emission and physico-mechanical properties 181
8.2.1 Physico-mechanical properties of wood-based panels 181
8.2.2 Case studies 182
8.3 Impact of formaldehyde-reducing strategies on machinability 189
8.3.1 Introduction 189
8.3.2 Case studies 190
8.4 Future perspectives 202
Index 207
