Which of the following has cross- linkesa.Dacron b.PVCc.polyethylened.vulcanized rubber

The material that has cross-links is vulcanized rubber.

Here's a step-by-step explanation:

1. Dacron: Dacron is a type of polyester that does not have cross-links. It is a linear polymer, which means its polymer chains do not have branches or cross-links.

2. PVC: Polyvinyl chloride (PVC) is also a linear polymer. While it can be modified to introduce some cross-linking, standard PVC does not have cross-links.

3. Polyethylene: Polyethylene is another linear polymer. It is made up of long chains of ethylene monomers and does not have cross-links.

4. Vulcanized Rubber: Vulcanization is a chemical process that introduces cross-links between the polymer chains of natural rubber. This process, invented by Charles Goodyear, makes the rubber more durable and heat-resistant. Therefore, vulcanized rubber is the material among the given options that has cross-links.