Question

When we burn nylon, why do we not get the smell of burning paper or burning hair?

Answer 1

Hint: Burning is the reaction of a substance with an oxidant (atmospheric oxygen) releasing energy in the form of heat and light. Nylon is an example of a polyamide. Paper is mainly composed of cellulose, hemicellulose, and lignin. Nylon is not a natural polymer. On burning, the atmospheric oxygen reacts with the material and converts it into an oxidized product.

Complete step by step answer:
When we say that a material is burned, it essentially means that it reacts with an oxidant (usually atmospheric oxygen) and energy is released in the form of heat and light. It is an exothermic reaction.
As we know the composition of paper is cellulose, hemicellulose, and lignin. It also contains small amounts of additives. The cellulose reacts with atmospheric oxygen to produce carbon dioxide, water, ash, soot, and some volatile organic compounds. These compounds are responsible for the characteristic smell of paper on burning.
Hair is mainly composed of the fibrous protein keratin.
Keratin is made up of a variety of amino acids including the sulfur-containing amino acid cysteine. This is responsible for the high disulfide content in hair. Burning of sulfur produces a characteristic pungent smell (smell of rotten eggs)
Nylon is a synthetic polymer made of repeating units connected by amide linkages. It is a polyamide usually formed by the reaction of a diamine with a dicarboxylic acid.
Unlike paper and hair which are made of natural polymers, nylon is made up of chemicals like diamine and dicarboxylic acid. This would give a characteristic smell different from that of paper or hair on burning.
Hence the smell produced on burning nylon is different from that produced by paper or hair.


Note:
Nylon is a generic designation of a class of synthetic polymers based on aliphatic or semi-aromatic polyamides. Hence, there are different types of nylons like nylon 66, nylon 6, etc. The monomers include diacids, diamines, lactams, and so on. Hence, different nylons can give a different smell of burning.