As a result, the dispersity of the reactor lies between that of a batch and that of a homogeneous CSTR.
12.
Dispersity ( ) or polydispersity index ( PDI ) is an indication of the broadness in the distribution of polymer chains.
13.
The effects of reactor type on dispersity depend largely on the relative timescales associated with the reactor, and with the polymerization type.
14.
In conventional bulk free radical polymerization, the dispersity is often controlled by the proportion of chains that terminate via combination or disproportionation.
15.
As a result, reactor type does not affect dispersity for free radical polymerization reactions in any noticeable amount as long as conversion is low.
16.
Thus, for the similar reasons as anionic polymerization, the dispersity for heterogeneous CSTRs lies between that of a batch and a homogeneous CSTR.
17.
The use of low dispersity standards allows the user to correlate retention time with molecular mass, although the actual correlation is with the Hydrodynamic volume.
18.
When introduced into a CSTR however, the residence time distribution for reactants in the CSTR affects the dispersity of the anionic polymer due to the anion lifetime.
19.
Such is the case also in biological polymers, where the dispersity can be very close or equal to 1, indicating only one length of polymer is present.
20.
By dissolving a polymer an insoluble high molar mass fraction may be filtered off resulting in a large reduction in M m and a small reduction in M n thus reducing dispersity.
