Can wood be melted

Why does wood ignite directly while other materials melt first?

background : I boiled eggs (very difficult) with a plastic spatula which wasn't very good. When I put it on the edge of the pan, it started to melt. To keep cooking I reached for a wooden spoon that can touch the pan without melting.

This made me wonder about the behavior of the materials. For example, if I had left the plastic spatula it would have melted, but if I had raised the temperature enough it would actually have ignited and caught a flame. If I did the same with the wooden spoon, it wouldn't melt when I raised the temperature, but it would eventually ignite.

Why are certain materials (in this case plastic) melted and then ignited, but wood seems to just skip melting and ignite directly?

I'm just suspecting that wood somehow has a higher melting point than its ignition point, but I'm not even sure that makes any physical sense. A google search led me to a strange looking forum with disappointing responses. My understanding of thermodynamics is only mathematical, but I am conceptually blind in this area. Maybe someone can shed more light on the darkness.

dmckee ♦

Either the spatula was made of completely unsuitable plastic or you are boiling your eggs much too hot. Spares them; Don't burn the taste of them.

M Barbosa

@dmckee I like her well done but it was a very sad spatula indeed

David White

A polymer chemist could probably give a better answer than me. Nevertheless, wood consists of a highly cross-linked polymer with a very high molecular weight, which consists of glucose monomers. All cross-links between molecules ensure that wood does not dissolve in water and does not melt. For an "analogy" to this, vulcanized rubber is also strongly cross-linked in its chemical structure. Have you ever seen an old tire melt before it burns?

M Barbosa

@ DavidWhite a polymer chemist would make no sense, such great answer. Remember that most things that are "fibrous" don't melt before burning (meat, plants, etc.).

philip_0008

Also surprising that the liquid egg solidifies when cooking :)

Wolphram jonny

When a substance undergoes a phase change such as melting, its chemical composition remains the same. However, when heat is added to the wood, the wood will oxidize before it can melt. Wood contains long-chain organic molecules that, when heated, break down into products such as charcoal, water, methanol and carbon dioxide. The physical structure of wood is destroyed and the resulting material cannot return to its original material. Due to the chemical, irreversible degradation of its components, wood does not melt. More details can be found at http://www.yalescientific.org/2010/05/everyday-qa-can-you-melt-a-wooden-log/

user115350

When we say that a log is ignited, it is the combustible gas given off by the match, but not the wood itself (you can say that is wood ignition, but I want to point that out). Heat degradation of long-chain wood molecule and release of flame gas. Unfortunately, heat cannot melt wood until it breaks its molecule. Others like wax can melt.

Declan

An interesting side question (chemistry) in my opinion would be what would happen to wood that is continuously heated in a vacuum.

Declan

.. Oh I'm sorry. I just followed your link :)

Sean

@ user115350: Strictly speaking, both the released gases ignite and burn as well as the wood itself; The gases create the great flames that rise above the wood, and the wood itself creates the glow that comes directly from the burning logs.

Sean

@Declan: It's called destructive distillation of wood and it produces charcoal, tar, and various other volatiles.