Chemical blowing agents are substances that produce gas when heated or chemically reacted, creating a cellular structure in materials like plastics and rubber. They are commonly used in the manufacturing of foams, providing lightweight and insulating properties. These agents can be classified into two main types: endothermic and exothermic. Endothermic agents absorb heat to generate gas, while exothermic agents release heat during the reaction. The choice of blowing agent affects the final product's density, strength, and thermal insulation properties, making them essential in various applications, including packaging and construction materials.