Resources | Subject Notes | Chemistry
This section describes two important polymers: nylon (a polyamide) and PET (a polyester). We will cover their structures and key characteristics.
A polyamide is a type of polymer where the repeating units are linked by amide bonds (-CONH-). These bonds are formed from a carboxylic acid group and an amine group.
Nylon is a polymer formed by the condensation polymerization of diamines and dicarboxylic acids. A common example is nylon-6,6, which is made from the reaction of hexamethylenediamine and adipic acid.
The structure of nylon can be represented as follows:
$$ \underbrace{-[NH(CH_2)_6NH] - [CO(CH_2)_4CO] -}_{Repeating Unit} $$
The amide linkage is crucial for the properties of nylon, providing strength and flexibility.
A polyester is a type of polymer where the repeating units are linked by ester bonds (-COO-). These bonds are formed from a carboxylic acid group and an alcohol group.
PET (polyethylene terephthalate) is a polyester made from the reaction of ethylene glycol and terephthalic acid.
The structure of PET can be represented as follows:
$$ \underbrace{-[CH_2-CH_2-O-CO-C_6H_4-COOH] - [CH_2-CH_2-O-CO-C_6H_4-COOH] -}_{Repeating Unit} $$
The ester linkage provides strength and resistance to deformation.
| Property | Nylon (Polyamide) | PET (Polyester) |
|---|---|---|
| Repeating Unit Bond | Amide (-CONH-) | Ester (-COO-) |
| Typical Monomers | Diamines and Dicarboxylic Acids | Ethylene Glycol and Terephthalic Acid |
| Strength | High | Strong |
| Elasticity | Good | Moderate |
| Resistance to Abrasion | Excellent | Good |
| Common Uses | Tires, Clothing, Ropes | Plastic Bottles, Clothing, Carpets |