Unsaturated polyesters are a type of synthetic polymer made by combining diols and dicarboxylic acids through a process called polycondensation. They contain double bonds in their molecular structure, which allows them to be cured or hardened when mixed with a crosslinking agent like styrene. This property makes them useful in various applications, including coatings, adhesives, and composite materials. These polymers are known for their durability, resistance to chemicals, and ability to be molded into different shapes. They are commonly used in industries such as automotive, construction, and marine, where strong and lightweight materials are essential for performance and longevity.