Which of the following is not an elastomer?

PVC

The correct answer is option 3. PVC.

Among the options provided, PVC (Polyvinyl chloride) is not an elastomer. PVC is a thermoplastic polymer, not an elastomer. Elastomers, on the other hand, are polymers with elastic properties, meaning they can stretch and return to their original shape after being stretched.

Let us break down each option:

1. Buna-S: This is a type of synthetic rubber, specifically a copolymer of butadiene and styrene. It is commonly used in the production of tires, conveyor belts, and various rubber products. Buna-S is an elastomer because it exhibits elastic properties, meaning it can stretch and return to its original shape after deformation.

2. Buna-N: Also known as nitrile rubber or NBR, Buna-N is a synthetic rubber copolymer of butadiene and acrylonitrile. It is known for its excellent resistance to oils, fuels, and chemicals, making it suitable for use in seals, gaskets, and hoses. Like Buna-S, Buna-N is an elastomer due to its elastic properties.

3. PVC (Polyvinyl chloride): PVC is a thermoplastic polymer, not an elastomer. Thermoplastics soften when heated and harden when cooled, but they do not exhibit significant elasticity like elastomers. PVC is widely used in construction, packaging, and various other applications due to its versatility and durability, but it does not have the elastic properties characteristic of elastomers.

4. Neoprene: Neoprene is a type of synthetic rubber known for its resistance to oils, chemicals, and weathering. It is commonly used in wetsuits, gaskets, and other applications where resistance to water and abrasion is important. Neoprene is an elastomer because it can stretch and return to its original shape, making it suitable for flexible applications.

So, among the options provided, PVC is the only one that is not an elastomer. It is a thermoplastic polymer with different properties compared to elastomers like Buna-S, Buna-N, and Neoprene.