Cross-Linking
The formation of covalent bonds between separate polymer chains.
Unit
Dimensionless
In depth
Cross-links tie the chains into a network, greatly increasing rigidity, strength and resistance to solvents and heat while reducing flexibility. A few cross-links give elasticity, as in rubber, while extensive cross-linking gives a hard, brittle thermoset.
Examples in the real world
Sulfur bridges in vulcanised rubber; disulfide bonds set into hair during a permanent wave.