How can elastomer-based adhesives act as either thermoplastics or thermosets?

Elastomer-based adhesives can function as either thermoplastics or thermosets depending on whether cross-linking is required for the adhesive to perform its intended function.1

• Thermoplastic behavior: In their thermoplastic form, elastomer-based adhesives do not require permanent chemical interlinking. They rely on physical entanglements or intermolecular associations, allowing them to soften when heated and harden when cooled without degrading. This makes them suitable for applications like hot-melt adhesives, where the material is applied as a liquid at elevated temperatures.123
• Thermosetting behavior: When performance requirements demand high-temperature strength or solvent resistance, the elastomer must be converted into a thermoset. This is achieved through vulcanization or curing, a process that creates permanent covalent cross-links between polymer chains. Once these chemical bonds are formed, the adhesive creates a permanent, heat-resistant network that will not flow or dissolve, even when heated.12

Essentially, the distinction lies in the molecular structure: if the adhesive remains a viscous liquid that can be re-melted, it acts as a thermoplastic; if it is chemically cured into a solid network, it acts as a thermoset.12