Polymerhärdning

Polymerhärdning, also known as polymer curing or vulcanization in the context of rubber, is a chemical process that converts a polymer into a more solid, rigid, and durable material. This transformation is typically achieved by forming cross-links between polymer chains. These cross-links create a three-dimensional network structure, which restricts the movement of individual polymer chains, thereby increasing the material's strength, stiffness, and resistance to heat and solvents.

The specific method of polymerhärdning depends on the type of polymer. For thermosetting polymers, such as epoxies and polyurethanes, curing is often initiated by heat, a catalyst, or a combination of both. This process is irreversible; once cured, the material cannot be re-melted or reshaped. In contrast, thermoplastics do not undergo permanent chemical cross-linking. Their "curing" or solidification upon cooling is a physical process of chain entanglement, allowing them to be re-melted and molded multiple times.

Vulcanization is a specialized form of polymerhärdning applied to elastomers, most notably rubber. It involves heating rubber with sulfur or other curing agents, which creates cross-links between the long polymer chains. This process significantly enhances the rubber's elasticity, tensile strength, and resistance to abrasion and temperature changes, transforming it from a sticky, weak material into the versatile and durable substance used in tires, hoses, and countless other applications. The degree of cross-linking directly influences the final properties of the cured polymer.