Copolymer hydrodynamic volume distribution in a free radical copolymerization process

Molecular weight averages and copolymer composition are commonly used as pr operty indices for copolymers. In gel permeation chromatography (GPC), copo lymer molecules are separated based on their hydrodynamic volumes in dilute solutions. For a copolymer with heterogeneity in the composition distribut ion, GPC chromatogram represents the hydrodynamic volume distribution which is not identical with its true molecular weight distribution that can be c alculated from a copolymerization kinetic model. In this paper, a new metho d is presented for modeling the hydrodynamic volume distribution of a copol ymer in a batch free radical copolymerization process. The hydrodynamic vol ume distribution is calculated by computing the weight fraction of polymers over a number of hydrodynamic volume intervals. Chain length and copolymer composition are related to hydrodynamic volume using the bivariate distrib ution function and the universal calibration method with composition depend ent Mark-Houwink constants.