Molecular structure
adjacent chains attached via covalent bonds
Carried out during polymerization or by a non-reversible reaction aftersynthesis (referred to as crosslinking)
Materials often behave very differently from linear polymers
Many “rubbery” polymers are crosslinked to modify their mechanical
properties; in that case it is often called vulcanization
Generally, amorphous polymers are weak and cross-linking adds strength: vulcanized rubber is polyisoprene with sulphur cross-links: