Which of the following is NOT a property of plastics?

Plastics are known for being lightweight materials, which is a significant advantage in various applications, such as automotive and packaging industries. They are typically much lighter than metals and other materials, contributing to their widespread use in design and manufacturing.

The correct answer highlights that "heavyweight" is not a property associated with plastics. Instead, plastics generally offer a low density, making them easy to handle and transport. This characteristic, along with their other properties—such as being good electrical insulators, having a good strength to weight ratio, and being resistant to corrosion—contributes to their versatility in different product designs. By understanding the properties of plastics, designers can make informed choices when selecting materials for specific applications.