In sealing technology, mainly representatives of two groups of macromolecular (polymeric) substances are used, i.e. substances of the groups of elastomers and thermoplastics.

Macromolecular substances are organic compounds whose molecules exist of several thousands, often even millions, of atoms which are known as macro, giant, string or chain molecules. They can be created either by modification of highly molecular natural materials (e.g. natural rubber) or by depositing low-molecular elements (so called monomers) through various chemical reactions (synthetic materials, plastics).