What is Wood (1) Wood components

[0:13]start off with the very basics of where wood comes from in the first place. So, what is wood? Wood is produced by trees from a process of photosynthesis where carbon dioxide and water and sunlight go to make carbohydrate, which we give the generic formula CH2O plus oxygen, which of course is in the air that we breathe. So this process of photosynthesis takes atmospheric carbon dioxide and puts it into the wood material. Wood itself is made up of three polymers, cellulose, hemicelluloses and lignin. And these are all derived from the basic carbohydrate that is produced during the photosynthesis process. Each of these polymers has a different role to play. Structurally, cellulose is responsible for giving the wood its strength. So it's very strong in tension. The hemicelluloses give wood its flexibility and the lignin is responsible for giving wood its stiffness. And combined together, they give wood its remarkable physical mechanical properties. There's one other component that we should never forget which is also in wood and which affects its behavior, and that's water. So really, water is the fourth component in wood. So in the next part of this lecture, I'll be talking about what water is.