What occurs to plywood when exposed to fire conditions?

When plywood is exposed to fire conditions, it undergoes a process known as delamination. This occurs because plywood is constructed from layers of wood veneer that are bonded together with adhesive. Under high temperatures, the adhesive that holds these layers together can break down, causing the layers of plywood to separate or "delaminate." This loss of integrity compromises the structural stability of the plywood, making it less effective in its intended application.

The other potential responses do not accurately describe the primary behavior of plywood under fire conditions. While plywood can ignite rapidly under sufficient heat—especially if it contains a high percentage of flammable adhesive—that is not the most distinctive or immediate effect. Similarly, although wood materials can exhibit expansion and warping when heated, delamination is a more pronounced and critical issue specific to plywood because of its laminated construction. Cooling down is not a relevant change that occurs during exposure to fire; instead, plywood is subjected to heat and can degrade significantly. Thus, delamination is the correct outcome that best characterizes the behavior of plywood in a fire scenario.