Question

Which of the following is an example of a thermosetting plastic material?

• A. PVC
• B. Polyester
• C. Polypropylene
• D. Urethanes

Answer 1

The Correct Option is D

To solve the question regarding which material is an example of a thermosetting plastic, let's first understand some basic concepts of plastics.

Thermosetting Plastics: These are polymers that irreversibly harden when heated. Once set, they cannot be remelted or remolded. This property is due to the strong covalent bonds formed during the polymerization process, which create a three-dimensional network. Common examples include Bakelite, epoxy resins, and polyurethanes.

Thermoplastics: These materials can be melted and remolded multiple times. They are held together by intermolecular forces that weaken upon heating, allowing reshaping. Examples include PVC (Polyvinyl Chloride) and Polypropylene.

Let's examine each option:

1. PVC (Polyvinyl Chloride): A thermoplastic. It can be melted and reshaped multiple times. Thus, it is not a thermosetting plastic.
2. Polyester: While certain types of polyester can be crosslinked and act like thermosetting plastics, in general, common polyester used in fibers and sheets behaves as a thermoplastic. Therefore, generally, it is not considered a thermosetting plastic.
3. Polypropylene: Also a thermoplastic known for its ability to be reshaped upon heating. Not a thermosetting plastic.
4. Urethanes: These are often used in forming polyurethane foams and elastomers, which belong to the category of thermosetting plastics. Polyurethanes form a rigid crosslinked structure upon curing and are commonly used in applications requiring durable and heat-resistant materials.

Based on the explanation above, urethanes (specifically polyurethanes) are an example of thermosetting plastic materials.

Therefore, the correct answer is:

Urethanes