Polyreaction distribution

Exploitation of Pendant Reactive Groups. Pendant and linkage forming stabilizing moieties can be created in this way. Macromolecular stabilizers thus formed have general structures B, C, and E (Scheme 1) and are formally structurally related to stabilizers prepared by other polyreactions. The distribution mode of stabilizing moieties and the presence of foreign structures and mentioned above represent the main difference between stabilizers prepared via different synthetic approaches. 

By means of plug flow reactor in totally homogeneous phase, they were able to prove, for the very initial instants of the polyreaction, a good agreement between the experimental distributions and the theoretical ones calculated from a reaction scheme established by kinetical analysis and mathematical modelling. 

Table 10.3.b-1 Molecular weight distributions resulting from polyreactions in various reactor types (from Gerrens [20])... 

As mentioned above, there is a specific relation between the mechanism of a polyreaction and the resulting molecular weight distribution of the formed polymer. In order to apply this measuring instrument, a sequence of oligomer distributions was produced in dependence on the reaction time, ratio Al/Ti (i.e., the concentration of active species), chain length of the starting Ti-component, monomer concentration, and temperature (see Figs. 12 and 13). 

Often, size exclusion chromatograms (SEC) (compare section 11.7, Size Exclusion Chromatography) of polymers under study are expressed as differential representations of molar mass dispersity. The chromatographic retention volumes are directly transformed into the molar masses. This approach renders useful immediate information about tendencies of molar mass evolution in the course of building or decomposition polyreactions but the absolute values of molar mass can be only rarely extracted from it. As a rale, polystyrene calibrations are applied for molar mass calculation so that one deals with the polystyrene equivalent molar masses, not with the absolute values. The resulting dispersity (distribution) functions may be heavily skewed because the linear part of the calibration dependence for the polymer under study may exhibit well different slope compared with the polystyrene calibration, which was employed for the transformation of retention volumes into molar masses. 

If the polymer thus produced is tempered or annealed for an extensive period (polyreaction carried out at low temperature, heating up of injection-molded material, etc.), the molecular-weight distribution is broadened because of the transamidation which occurs. Acid-catalyzed aminolysis predominates in transamidation ... 

Many fluid mixtures encountered in chemical and hydrocarbon processing industries are ill-defined in the sense that they contain far too many components for a detailed compositional analysis and subsequent modeling in terms of pure component mass balances. Common examples of such mixtures are frequently related to processes of high economic relevance and include petroleum and reservoir fluids as well as polymer solutions and polyreaction systems [6]. The concept of continuous thermodynamics is a well-established approach for the modeling of these mixtures [2, 6]. The compositional complexity of the mixture is represented in terms of a time-dependent continuous distribution function of some characterizing fluid property (e.g. molecular weight,... 

Wulkow, M., 1996. The simulation of molecular weight distributions in polyreaction kinetics by discrete Galerkin methods. Macromol. Theory Simul. 5, 393-416. 

MOLECULAR WEIGHT DISTRIBUTIONS RESULTING FROM POLYREACTIONS PREDICTED BY VARIOUS REACTOR MODELS"... 

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