Thermosetting plastics are a type of polymer that, once cured or hardened, cannot be remolded or reshaped. This process involves a chemical reaction that creates a strong, cross-linked structure, making these materials durable and heat-resistant. Common examples include epoxy resins and phenolic resins, which are often used in applications requiring high strength and stability. These plastics are widely used in various industries, including automotive, electronics, and construction. Their ability to withstand high temperatures and resist deformation makes them ideal for products like circuit boards and insulation materials. However, once set, they cannot be recycled or reused, which poses environmental challenges.