Which of the following materials is NOT allowed for floor sealant?

The correct answer indicates that butyl is not an acceptable material for floor sealant in the context of dry van containers. The materials typically used for floor sealants in dry vans are chosen based on their durability, weather resistance, and compatibility with other materials present in the container.

Chloroprene, urethane, and polyurethane are all commonly used sealants due to their strong adhesion and resistance to various environmental factors such as moisture and temperature fluctuations, which are essential for maintaining the integrity of the flooring in transport conditions.

Butyl, while it does have some useful properties such as excellent flexibility and resistance to aging, is generally not preferred for floor sealant applications in dry vans. This is largely due to its susceptibility to damage under certain conditions, which may not provide the necessary durability required for the heavy-duty use typical in shipping and transporting goods.

Understanding the properties and suitability of each material helps in determining why butyl is excluded from acceptable sealants for dry van flooring.