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BI-MwA分子量測量應(yīng)用案例-3
閱讀：305 發(fā)布時間：2014-12-6
文獻名： Online Monitoring of the Final, Divergent Growth Phase in the Step-Growth Polymerization of Polyamines
作者： Ray S. Farinato , Joe Calbick , Gina A. Sorci , Fabio H. Florenzano , and Wayne F. Reed
Physics Department, Tulane University, New Orleans, Louisiana, Cytec Industries, Inc., 1937 W. Main St., Stamford, Connecticut, and Universidade do Vale do Sapucaí - UNIVÁS, Pouso Alegre -MG-Brazil - 37550-000
摘要：Using automatic, continuous online monitoring of polymerization reactions (ACOMP) the final, divergent growth phase (FDGP) of the condensation polymerization of dimethylamine, epichlorohydrin, and ethylenediamine was monitored, which produced a highly ramified, polyelectrolytic polyamine. The weight average mass, Mw, increased exponentially during the FDGP, whereas weight averaged intrinsic viscosity [η]w increased slowly, reaching a plateau. Multi-detector gel permeation chromatography (GPC) revealed that polymers of mass 20 000 to 106 are branched and self-similar, but above this mass, [η] increases less strongly with M. This appears to be due to higher order ramification, a precursor to gelation. The ACOMP trends in Mw and [η]w provide direct online evidence of this process. It is shown computationally that a mere increase in polydispersity cannot explain this behavior. GPC showed the mass distribution becomes highly asymmetric as conversion increases. A plausible kinetic model for the distribution asymmetry is introduced, and a complementary model for the effects of higher order ramification on [η]w.