Principles of Wood Science and Technology

The principal author published the first edition of a book entitled in German "Technologie des Holzes" (Springer-Verlag) in the year 1936. This book was available only in photostat copy form in the United States during World War n. A translation into the English language was later made in Australia. Due to many hampering factors caused by World War n it was not unti11951 that the second edition of the first volume of thir:; book with the enlarged title (translated) "Technology of 'Vood and W ood Based Materials" was published. The se co nd volume followed in 1955. The enormOllS expansion of wood seience and technology within less than two deeade,: is evident from a comparison of the number of pages of these two editions. The first edition eomprises 764 pages, the two volumes of the second edition 2231 pages. More recently, it becamc evident that an English version in a condensed up­ to-date form was needed. Therefore, the principal author decided to publish a book on "Principles of W ood Science and Technology" in English. The first volume dealt with solid wood, this second volume deals with wood based materials. U sing the ward "Principles" in the title of the condensed book this led directly to abandoning ft11 detailed historie al reviews, explanations, ftnd discussions of mftchines and processes.

1. Adhesion and Adhesives for Wood.- 1.0 General Considerations about Gluing.- 1.1 Physical-Chemical Principles of Gluing.- 1.1.1 Cohesion and Adhesion.- 1.1.2 Intermolecular Forces, Polarity.- 1.1.3 Influence of Temperature, Concentration and Amount of Polymerization.- 1.1.4 Influence of pH Value on the Hardening of Glue Joints.- 1.1.5 Colloidal State of Wood Glues, Sols and Gels.- 1.1.6 Rheology of Glues.- 1.1.7 Phenomena of Hardening.- 1.1.8 Fortifying (Upgrading), Filling, Extending of Glues for Wood.- 1.2 Strength Improvement and Stresses in Glue Joints.- 1.3 Testing of Glue Joints.- 1.4 Summarized Results of Tests for Various Glues.- 1.5 Effect of Wood Species and Moisture Content on the Strength of Glue Joints.- 1.6 Pretreatment of Wood Prior to Gluing.- 1.7 Glue Spreading.- 1.8 Pressing of Glued Parts and of Laminated Wood.- 1.9 Difficulties and Defects in Gluing 2S.- 1.10 Natural Glues.- 1.10.1 Starches, Dextrins and Natural Gums.- 1.10.2 Protein Glues.- 1.10.2.1 Animal Glues, Manufactured from Hide, Sinews, Bones.- 1.10.2.2 Casein Glues.- 1.10.2.3 Blood Albumin Glues.- 1.10.2.4 Soyahean (or Soybean) Glues and Peanut-Meal Glues.- 1.10.3 Shellac.- 1.10.4 Asphalt (Bitumen) and Mastic.- 1.10.5 Natural and Synthetic Rubber (Neoprene).- 1.10.6 Glues on Cellulose Basis.- 1.10.6.1 Cellulose Acetates.- 1.10.6.2 Cellulose Esters.- 1.10.7 Silicate of Soda.- 1.11 Synthetic Glues.- 1.11.0 General Considerations.- 1.11.1 Phenol-Formaldehyde Resin Glue.- 1.11.1.1 History of Phenolic Resin Glues.- 1.11.1.2 Manufacture and Chemistry of Phenol-Formaldehyde Resins.- 1.11.1.3 Application of Phenolic Resin Glues.- 1.11.1.4 Properties of Phenolic Resin Glue Joints.- 1.11.2 Resorei nol -Formaldehyde Adhesives.- 1.11.3 Urea-Formaldehyde Resin Adhesives.- 1.11.3.1 History of Urea Resin Glues.- 1.11.3.2 Manufacture and Chemistry of Urea-Formaldehyde Glues.- 1.11.3.3 Hardening of Urea-Formaldehyde Resins.- 1.11.4 Melamine-Formaldehyde Resin Adhesives.- 1.11.4.1 History, Chemistry, and Manufacture of Melamine-Formaldehyde Adhesives.- 1.11.4.2 Application of Melamine-Formaldehyde Adhesives.- 1.11.4.3 Hardening of Melamine Adhesives.- 1.11.4.4 Properties of Melamine-Formaldehyde Resin Glue Joints.- 1.11.4.5 Fortifying or Upgrading of Urea Adhesives.- 1.11.4.6 Surface Coating of Wood Based Materials.- 1.11.5 Thermoplastic Resin Adhesives.- 1.11.5.1 General Properties and Manufacture.- 1.11.5.2 Cellulose Adhesives.- 1.11.5.3 Polyvinyl Acetates (PV A).- 1.11.6 Other Synthetic Organic Adhesives.- 1.11.6.1 Epoxy Glues.- 1.11.6.2 Polyurethane Adhesives.- Literature Cited.- 2. Solid Modified Woods.- 2.0 Introduction.- 2.1 Fundamentals of Impregnation.- 2.1.1 Flow through True Capillaries.- 2.1.2 Flow through Softwoods.- 2.1.2.1 Structure Involved.- 2.1.2.2 Permeability to Liquids and Gases.- 2.1.2.3 Longitudinal versus Transverse Flow.- 2.1.2.4 Mean Pit Membrane Pore Numbers and Radii.- 2.1.2.5 Effect of Gas-Liquid Interphases.- 2.1.3 Diffusion in Wood.- 2.2 Treating Methods.- 2.2.1 Sap Displacement.- 2.2.2 Capillary Absorption and/or Diffusion.- 2.2.3 Pressure Methods.- 2.3 Wood Preservation against Attack by Organisms.- 2.3.1 General.- 2.3.2 New and Modified Treating Methods.- 2.3.2.1 Double Diffusion.- 2.3.2.2 Modified Boucherie Process.- 2.3.2.3 Predrying Methods.- 2.3.2.4 Cellon Process.- 2.4 Wood Preservation against Fire.- 2.4.1 Fire Hazards.- 2.4.2 Fire Retardant Treatment.- 2.5 Dimensional Stabilization.- 2.5.1 Cross-Laminating.- 2.5.2 External Coatings.- 2.5.3 Internal Coatings.- 2.5.4 Reduction in Hygroscopicity.- 2.5.4.1 Heat Stabilization.- 2.5.5 Cross-Linking.- 2.5.6 Bulking Treatments.- 2.5.6.1 Salt Treatments.- 2.5.6.2 Sugar Treatment.- 2.5.6.3 Polyethylene Glycol Treatment.- 2.5.6.4 Wax Treatment.- 2.5.6.5 Phenolic Resin Treatment (Impreg).- 2.5.6.5.1 Treating Processes.- 2.5.6.5.2 Properties of Impreg.- 2.5.6.5.3 Uses for Impreg.- 2.5.6.6 Vinyl Resin Treatment.- 2.5.6.6.1 Strength Properties.- 2.5.6.7 Acetylated Wood.- 2.5.6.8 Other Treatments.- 2.6 Densified Wood.- 2.6.1 Densifying by Impregnation.- 2.6.1.1 Metalized Wood.- 2.6.2 Densifying by Compression.- 2.6.2.1 Plasticizing Wood.- 2.6.2.1.1 Bending Wood.- 2.6.2.2 Resin-Treated Compressed Wood (Compreg).- 2.6.2.2.1 Making Compreg.- 2.6.2.2.2 Properties and Uses of Compreg.- 2.6.2.3 Stable Untreated Compressed Wood (Staypak).- Literature Cited.- 3. Veneer, Plywood and Laminates.- 3.1 Introduction.- 3.1.1 History, Status and Trends in Germany and North America.- 3.1.2 World Production and Analysis of Consumption.- 3.2 Veneer.- 3.2.1 Wood Species.- 3.2.2 Pretreatment of Logs Prior to Slicing and Peeling.- 3.2.2.1 Protection of Logs against Decay and Checking.- 3.2.2.2 Steaming and Boiling (Cooking) of Round Logs.- 3.2.2.3 Debarking or Cleaning.- 3.2.3 Veneer Sawing.- 3.2.3.1 Introduction.- 3.2.3.2 Circular Sawing of Veneer.- 3.2.3.3 Band Sawing of Veneer.- 3.2.3.4 Horizontal Gang Saws for Veneer Manufacturing.- 3.2.4 Veneer Slicing.- 3.2.4.1 Introduction.- 3.2.4.2 Horizontal Slicing of Veneer.- 3.2.4.3 Vertical Slicing of Veneer.- 3.2.5 Veneer Rotary-Peeling.- 3.2.6 Veneer Handling from the Slicer or Lathe.- 3.2.7 Trimming and Clipping.- 3.2.8 Veneer Peeling Lines.- 3.2.9 Veneer Drying.- 3.2.9.1 Introduction.- 3.2.9.2 Types of Veneer Dryers, Conventional Drying Times.- 3.2.9.3 Physics of Veneer Drying.- 3.3 Plywood.- 3.3.0 General Considerations.- 3.3.1 Principles of Manufacture.- 3.3.1.1 Veneer Jointing and Repairing.- 3.3.1.2 Applying the Adhesive.- 3.3.1.3 Pressing.- 3.3.1.4 Conditioning.- 3.3.1.5 Panel Finishing (Sizing and Thicknessing).- 3.3.1.5.1 Sizing or Trimming.- 3.3.1.5.2 Thicknessing (Sanding or Scraping).- 3.4 Properties of Plywood.- 3.4.0 Preamble.- 3.4.1 Density, Weight per Unit Area.- 3.4.2 Moisture Content, Absorption and Swelling.- 3.4.3 Thermal Conductivity, Acoustical Properties.- 3.4.4 Mechanical Properties.- 3.4.4.1 Elasticity and Rigidity.- 3.4.4.2 Strength Properties.- 3.4.4.2.0 General Considerations.- 3.4.4.2.1 Tensile Strength.- 3.4.4.2.2 Compressive Strength.- 3.4.4.2.3 Bending Strength.- 3.4.4.2.4 Shear Strength.- 3.4.4.2.5 Hardness.- 3.4.5 Technological Properties.- 3.4.6 Resistance against Destruction.- Literature Cited.- 4. Sandwich Composites.- 4.0 Introduction.- 4.1 Basic Design Principles.- 4.1.1 Sandwich Bending Stiffness.- 4.1.2 Sandwich Extensional Stiffness.- 4.1.3 Sandwich Shear Stiffness.- 4.1.4 Facing Stresses.- 4.1.5 Core Stresses.- 4.1.6 Minimum Weight Sandwich Composites.- 4.1.7 Local Failure Modes.- 4.2 Materials and Fabrication.- 4.2.1 Facings.- 4.2.2 Cores.- 4.2.3 Adhesives.- 4.2.4 Sandwich Assembly.- 4.2.5 Inspection.- 4.2.6 Test Methods.- 4.2.7 Repair.- 4.3 Structural Components.- 4.3.1 Beams.- 4.3.2 Columns.- 4.3.3 Plates.- 4.3.3.1 Plates under Normal Load.- 4.3.3.2 Plates under Edge Loads.- 4.3.3.2.1 Flat Panels under Edgewise Compression or Bending.- 4.3.3.2.2 Flat Panels under Edgewise Shear.- 4.3.3.3 Combined Loads.- 4.3.4 Cylindrical Shells.- 4.3.4.1 Cylindrical Shells under External Radial Pressure.- 4.3.4.2 Cylindrical Shells under Torsion.- 4.3.4.3 Cylindrical Shells under Axial Compression or Bending.- 4.3.4.4 Cylinders of Sandwich under Combined Loads.- 4.4 Dimensional Stability.- 4.5 Durability.- Literature Cited.- 5. Particleboard.- 5.0 History of Production, Consumption and Use of Particleboard.- 5.1 Raw Materials.- 5.1.1 Wood and Other Ligno-Cellulose Materials.- 5.1.1.0 General Considerations.- 5.1.1.1 Unprocessed Forest Products.- 5.1.1.2 Industrial Wood Residues.- 5.1.1.3 Flax Shives.- 5.1.1.4 Bagasse.- 5.1.2 Adhesives.- 5.1.2.1 Urea- and Melamine-Formaldehyde Resins.- 5.1.2.2 Phenolic Resin Binders.- 5.1.2.3 General Rules for Chip Resination.- 5.1.3 Additives.- 5.1.3.1 Water Repellents.- 5.1.3.2 Extenders.- 5.1.3.3 Fungicides, Insecticides.- 5.1.3.4 Fire Retardants.- 5.2 General Technology.- 5.2.0 Introduction.- 5.2.1 Particle Preparation.- 5.2.1.0 General Considerations.- 5.2.1.1 Wood Yard, Conveying of Raw Wood, Metal Detection.- 5.2.1.2 Moisture Content.- 5.2.1.3 Barking (Debarking).- 5.2.1.4 Reduction of Wood.- 5.2.1.4.1 Crosscutting, Splitting.- 5.2.1.4.2 Primary Reduction, Knife Hogs.- 5.2.1.4.3 Secondary Reduction, Hammer-Mill Hogs, Toothed Disk-Mills, Impact Disk-mills.- 5.2.1.4.4 Shaving or Flake Production, Disk Type Chippers, Cutter Spindle and Cutter Cylinder (Cutter Head) Chippers.- 5.2.1.4.5 After-Reduction.- 5.2.1.4.6 Summary.- 5.2.2 Drying of Chips.- 5.2.2.0 General Considerations.- 5.2.2.1 Dryer Types.- 5.2.3 Size Separation (Classifying) by Screening or Sifting.- 5.2.4 Conveying of Chips.- 5.2.5 Storage of Chips (Wet and Dry Bins or Silos).- 5.2.5.0 General Considerations.- 5.2.5.1 Horizontal Storage Bins.- 5.2.5.2 Vertical Storage Bins.- 5.2.5.3 Rotating Storage Bins.- 5.2.6 Dosing (Weighing and. Volumetric Dosing).- 5.2.7 Chip Blending.- 5.2.7.0 General Considerations.- 5.2.7.1 Batch Operation.- 5.2.7.2 Continuous Operation.- 5.2.8 Mat-Laying (Chip-Spreading).- 5.2.8.0 General Considerations.- 5.2.8.1 Distribution of the Particles, Manually or by Auxiliary Devices.- 5.2.8.2 Terms, Failures, Volumetric and Gravimetric Dosing of the Material.- 5.2.8.3 Spreading Machines and Spreader Heads.- 5.2.8.4 Resultant Mat.- 5.2.9 Prepressing, Wetting, Flat Pressing (Presses and Associated Equipment), Methods of Operation.- 5.2.9.0 General Considerations.- 5.2.9.1 Prepressing.- 5.2.9.2 Single and Multi-Daylight Presses.- 5.2.9.2.0 General Considerations.- 5.2.9.2.1 Relative Investment Costs.- 5.2.9.2.2 Technological Aspects.- 5.2.9.2.3 Effect of Chip Moisture Content.- 5.2.9.2.4 Effect of Press Platen Temperature.- 5.2.9.2.5 Effect of Curing Time on Physical Properties of Particleboard.- 5.2.9.2.6 Influence of Quantity of Hardener and Proportion of Formaldehyde in the Urea Resin on Quality of Particleboard.- 5.2.9.2.7 Other Technological Aspects.- 5.2.9.3 Caulless Pressing Systems.- 5.2.9.3.0 General Considerations.- 5.2.9.3.1 Tray-Belt Molding System.- 5.2.9.3.2 Tablet System.- 5.2.9.3.3 Continuous Belt System.- 5.2.9.3.4 Calender Particleboard Process; System Mende-Bison.- 5.2.10 Board Finishing (Sizing and Sanding or Thicknessing).- 5.2.10.0 General Considerations.- 5.2.10.1 Sizing.- 5.2.10.2 Sanding.- 5.2.11 Particleboard — Plastic Combinations, Printing on Particleboard.- 5.2.11.0 General Considerations.- 5.2.11.1 Types of Laminates for Particleboard.- 5.2.11.2 Structure, Manufacture, and Testing of Laminated Particleboard.- 5.2.11.3 Printing on Particleboard.- 5.2.12 Extruded Particleboard.- 5.2.12.0 General Considerations.- 5.2.12.1 Vertical Extruders.- 5.2.12.2 Horizontal Extruders.- 5.2.13 Molded Particle Products.- 5.2.13.0 General Considerations.- 5.2.13.1 Thermodyn Process.- 5.2.13.2 Collipress Process.- 5.2.13.3 Werzalit Process.- 5.3 Some Additional Layouts.- 5.4 Properties of Particleboard.- 5.4.0 General Considerations.- 5.4.1 Factors Affecting the Properties of Particleboard.- 5.4.2 Testing of Particleboard, Standards.- 5.4.3 Density, Weight per Unit Area.- 5.4.4 Moisture Content, Absorption and Swelling.- 5.4.5 Thermal Conductivity.- 5.4.6 Acoustical Properties.- 5.4.7 Mechanical Properties.- 5.4.7.0 General Considerations.- 5.4.7.1 Theoretical Approach to Particleboard Mechanics.- 5.4.7.2 Elasticity and Rigidity.- 5.4.7.3 Tensile Strength.- 5.4.7.3.1 Tensile Strength, Parallel to Board Plane.- 5.4.7.3.2 Tensile Strength Perpendicular to Board Plane, Face Strength.- 5.4.7.4 Compressive Strength.- 5.4.7.5 Bending Strength, Creep, Fatigue.- 5.4.7.5.1 Bending Strength, Modulus of Rupture.- 5.4.7.5.2 Deflection, Modulus of Elasticity.- 5.4.7.5.3 Creep, Relaxation.- 5.4.7.5.4 Fatigue, Endurance.- 5.4.7.6 Impact Strength, Punetural Resistance.- 5.4.7.7 Shear Strength.- 5.4.7.7.0 General Considerations.- 5.4.7.7.1 Compression-Shear Tests.- 5.4.7.7.2 Tension-Shear Tests.- 5.4.7.7.3 Torsion-Shear Tests.- 5.4.7.8 Hardness.- 5.4.8 Technological Properties.- 5.4.8.0 General Considerations.- 5.4.8.1 Surface Quality.- 5.4.8.2 Accuracy of Dimensions, Surface Texture and Stability.- 5.4.8.3 Machining Properties.- 5.4.8.4 Nail-Holding and Screw-Holding Ability.- 5.4.8.4.1 Nails.- 5.4.8.4.2 Screws.- 5.4.9 Resistance to Destruction.- 5.4.9.1 Abrasion (Wear) Resistance.- 5.4.9.2 Resistance to Biological Attack.- 5.4.9.2.1 Fungi (Decay).- 5.4.9.2.2 Insects, Termites.- 5.4.9.3 Reaction to Fire.- 5.4.9.3.0 General Considerations.- 5.4.9.3.1 Aspects of Tests.- 5.4.9.3.2 Wood and Wood Based Panels in Fire.- Literature Cited.- 6. Fiberboard.- 6.0 Types of Fiberboard.- 6.1 History and Development.- 6.2 General Outline of Processes.- 6.3 Raw Materials.- 6.3.1 Wood.- 6.3.2 Bark.- 6.3.3 Modified Wood Raw Materials.- 6.3.4 Non-Wood Fibrous Raw Materials.- 6.4 Storage of Raw Material.- 6.5 Raw Material Preparation.- 6.5.1 Debarking of Wood.- 6.5.2 Chipping, Magnetic Separating, Screening.- 6.5.3 Storing.- 6.5.4 Wetting.- 6.6 Pulping (Wet Processes).- 6.6.1 Mechanical Pulping.- 6.6.2 Chemical-Mechanical Pulping.- 6.6.3 Thermal-Mechanical Pulping.- 6.6.3.1 General Considerations.- 6.6.3.2 Asplund Process (Defribrator Method).- 6.6.4 Explosion Process.- 6.7 Manufacture of Insulation Board.- 6.7.1 Sizing.- 6.7.2 Mat or Sheet Formation.- 6.7.3 Drying.- 6.7.4 Additional Processing Operations.- 6.8 Manufacture of Hardboard.- 6.8.1 Sizing.- 6.8.2 Mat or Sheet Formation.- 6.8.2.1 Wet Felting.- 6.8.2.2 Air Felting.- 6.8.3 Hot Pressing.- 6.8.4 Heat Treatment and Oil Tempering.- 6.8.5 Humidification and Conditioning.- 6.8.6 Trimming and Additional Processing.- 6.8.7 Losses and Yield in Manufacture, Production Costs.- 6.8.8 Special Fiberboards.- 6.9 Properties of Fiberboard.- 6.9.0 General Considerations, Tests, Uses.- 6.9.1 Density, Weight per Unit Area.- 6.9.2 Moisture Content, Absorption and Swelling.- 6.9.3 Thermal Conductivity.- 6.9.4 Acoustical Properties.- 6.9.5 Mechanical Properties.- 6.9.5.0 General Considerations.- 6.9.5.1 Elasticity.- 6.9.5.2 Bending Strength, Creep, Fatigue.- 6.9.5.2.1 Bending Strength or Modulus of Rupture.- 6.9.5.2.2 Creep and Relaxation.- 6.9.5.2.3 Fatigue, Endurance.- 6.9.5.3 Impact Strength, Puncture Resistance.- 6.9.5.4 Tensile Strength.- 6.9.5.5 Compressive Strength.- 6.9.5.6 Shear Strength (Delamination).- 6.9.5.7 Hardness.- 6.9.6 Technological Properties.- 6.9.6.0 General Considerations.- 6.9.6.1 Surface Quality.- 6.9.6.2 Accuracy of Dimensions, Surface Texture and Stability.- 6.9.6.3 Working, Machining, Moldability of Hardboard.- 6.9.6.4 Nail- and Screw-Holding Ability.- 6.9.7 Resistance to Deterioration.- 6.9.7.1 Abrasion (Wear) Resistance.- 6.9.7.2 Resistance to Biological Attacks.- 6.9.7.3 Behavior in Fire.- Literature Cited.- Conversion Factors.- Author Index.