Spray polyurethane does not give off gases or fumes when dry, due to its chemical polymerization reaction and curing process. Here’s a detailed explanation:
- Chemical reaction: Spray polyurethane is formed by the reaction of two chemical components: a polyol and an isocyanate. When mixed, they react to form a polyurethane foam.
- Polymerization and curing: This reaction is polymerization, where the molecules of the two components bond to create long polymer chains. This polymerization process transforms the liquids into a solid, stable foam. Once this reaction is complete and the foam has hardened, the chemical structure is stable and no longer releases significant gases or vapors.
- Closed-cell formation: In many spray polyurethane formulations, particularly closed-cell foams, the bubbles or cells created during expansion and solidification are hermetically sealed. This means that the gases used to expand the foam are trapped in these cells, preventing any subsequent release of gases or vapors.
- No volatility: Once spray polyurethane has fully cured, it becomes inert: its components are no longer volatile. This means it will not release chemicals into the air in the form of gases or vapors.
Compliance with safety standards: modern spray polyurethane formulations are designed to be safe and comply with environmental and safety standards, reducing the risk of harmful fumes after application.