Degree of Polymerisation
The number of monomer units in an average polymer chain.
Formula / equation
DP = M_polymer / M_monomer
Unit
Dimensionless
In depth
Mechanical strength rises with the degree of polymerisation until the chains are long enough to entangle, after which it levels off while the melt becomes increasingly difficult to process. Controlling chain length is therefore central to producing usable material.
Examples in the real world
Commercial polythene with a degree of polymerisation of tens of thousands; ultra-high molecular weight grades far higher.