CHEM-E2105 - Wood and Wood Products, 08.01.2019-12.04.2019
This course space end date is set to 12.04.2019 Search Courses: CHEM-E2105
Topic outline
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A lightweight honeycomb structural material, with a specific strength three times greater than that of mild steel, made from an advanced, self-assembling, nano-composite synthesised from abundant, renewable resources and using only solar energy in its manufacture. Damage tolerant, long-lasting, but completely biodegradable when triggered to do so, this material is also widely available and can be further processed into a vast array of products and structures with minimal fuss or further energy input. This really sounds like a futuristic material, yet it is already being produced and has been for hundreds of millions of years – it is, of course, wood!
Wood has been used for so long by humankind that we rarely, if ever, stop to think about what wood really is, yet when we start to study wood, we realise that is an extremely complex and elegant material that we really do not know much about. Wood is not without its problems that is for sure! It has a nasty habit of biodegrading when you least want it to – just add water and it will happily rot away, acting a food source to a wide variety of micro-organisms. It reacts to changes in the ambient humidity by altering its dimensions and sometimes its shape as well. However, as building material it is in many ways unparalleled, and by re-constituting wood in the form of a composite, many of its less desirable properties can be eliminated. In addition to wood’s interesting and very useful physical properties, of one the most attractive features of wood, in the drive for a more sustainable future, is its ability to store carbon from the atmosphere as part of its structure. During photosynthesis atmospheric carbon dioxide is sequestered and is used to form the wood structure. Approximately 1.75 kg of CO2 is required to make 1 kg of dry wood and this ‘captured’ CO2 is only released to back to the atmosphere when wood is burned or when it biodegrades. This means that long-lasting structures built of wood and wood-based composites actively store carbon, removing it from the atmosphere for as long as they exist, which can be for decades or even centuries, and in the end the wood can be burned for energy recovery or, better still, used as the basis for chemicals, or other products.
Wood’s propensity to interact with moisture can be put to good effect in helping to mediate the interior environments of buildings. As the humidity level rises, wood adsorbs moisture from the surroundings and, when the humidity drops, the stored moisture is released. In this way wood acts as a buffer, helping to reduce large fluctuations in relative humidity, arguably making for a more comfortable living environment. These attributes and others are gradually being recognised and there is greater and greater interest in the use of wood for construction as well as for a range of other applications. Many of the properties of wood - which are sometimes viewed as problems - can be altered by creating composites and engineered wood materials, like glue laminated timber – glulam, plywood and laminated veneer lumber. Wood can also be extremely resource efficient. By forming wood-composites, small dimensioned timbers, manufacturing wastes like sawdust or recovered wood can be used to create useful functional material. Wood can also be modified in one of a number of ways to reduce its susceptibility to bio-deterioration and dimensional changes; by altering the chemical structure of wood new functionality can be added. Modified wood products such as ThermoWood is just one example of how research is now able to give a new lease of life to a very traditional material. Wood still has much to teach us and as we learn more we will find new ways in which it can be utilised in a sustainable future.
Welcome to the Wood and Wood products course, where you will learn more about the intriguing properties of wood and what can be done with it!
Period III
Date
Topic/activity
Content
8.1
Lecture: introduction
Information about the course and background, wood formation, environmental factors, wood structure, basic terms and concepts
11.1
Lecture: wood structure
The anatomy of wood and relationship to properties
15.1
NO LECTURE
18.1
Lecture: mass-volume relationships
Bulk density, cell-wall density, porosity and fluid flow in wood
22.1
NO LECTURE
25.1
Lab: wood anatomy practical
Introduction to task and familiarization (students will complete the assignment in own time as pairs)
29.1
NO LECTURE
1.2
Lecture: wood-water relationships I
States of water in wood; moisture content; fibre saturation point; sorption; equilibrium moisture content
5.2
Lecture: wood-water relationships II
Moisture buffering; heat of sorption; dimensional changes; effect on mechanical and physical properties
8.2
Lecture: mechanics of wood I - elastic and strength properties
The orthotropic nature of wood; elastic properties of the wood cell wall and wood; tensile, compressive and shear properties
12.2
Lecture: mechanics of wood II - fracture and failure in wood
Toughness; cracks and crack-like defects; the nature of cracks; fracture mechanics; interfaces as crack stoppers; energy absorbing mechanisms
15.2
NO LECTURE
Period IV
Date
Topic/activity
Content
26.2
Lecture: mechanics of wood III - creep, stress relaxation and fatigue
Creep and stress relaxation, fatigue: viscoelasticity, mechano-sorption, S-N curves etc.
27.2
Lab: wood mechanics - fracture
Introduction to the assignment and theoretical background to the assignment (students will complete the assignments in pairs at times agreed with the teacher/instructor)
5.3
Lecture: manufacture of solid wood products
Scanning, sawing, grading, drying
6.3
NO LECTURE
12.3
NO LECTURE
13.3
Lecture: manufacture of veneer-based wood products
Plywood and LVL, soaking, peeling, drying, gluing, pressing and properties
19.3
NO LECTURE
20.3
NO LECTURE
26.3
Lecture: manufacture of wood-based panels
Structure-property relationships, size reduction, drying , pressing physics,
27.3
Exam revision