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Degree of polymerization

The degree of polymerization, or DP, is the number of repeat units in an average polymer chain at time t in a polymerization reaction [1]. The length is in monomer units. The degree of polymerization is a measure of molecular weight. For most industrial purposes, lengths in the thousands or tens of thousands are desired.

For a homopolymer, the degree of polymerization may be calculated as shown bellow

DP = Total MW of the polymer/MW of the repeating unit

Mn = XnMo

In polycondensation, in order to achieve a high degree of polymerization (and hence molecular weight), Xn, a high fractional monomer conversion, p, is required, as per Carothers' equation: Xn = 1/(1−p). A monomer conversion of p = 99% would be required to achieve Xn = 100.

Correlation with physical properties


Polymers with identical composition but different total molecular weights may exhibit different physical properties. In general, increasing degree of polymerization correlates with higher melting temperature [2] and higher mechanical strength.

See also


  1. ^ Gold Book definition Link
  2. ^ Flory, P.J. and Vrij, A. J. Am. Chem. Soc.; 1963; 85(22) pp3548-3553
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Degree_of_polymerization". A list of authors is available in Wikipedia.
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