翻譯 chemistry

幫我譯做中文 一d好chemistry既字就keep番都得
thanks so much!

As
the resin becomes hotter it thermally decomposes and the smaller
molecules produced in this way join the other burning molecules and
contribute to the flame. By this stage the wood that is immediately
beneath the burning surface, where there is no oxygen, starts to undergo
a type of thermal decomposition known as pyrolysis. This is a reaction
in which the large polymer molecules of cellulose, hemicellulose and
lignin break down into smaller molecules. The absence of oxygen ensures
that ignition does not occur. This causes a large volume of gas to be
produced within the wood. As the gas pressure increases the gas forces
its way out, simultaneously opening up the structure of the wood and
making it porous. Once the small molecules from pyrolysis reach the
surface they instantly burst into flames and contribute to the heating
effect.