Measurement rate polymer microstructure

Measurements of polymerization rate and parallel measurements on the resultant polymer microstructure in the butadiene/DIPIP system cannot be reconciled with the supposition that only one of the above diamine solvated complexes (eg. Pi S) is active in polymerization 162). This is probably true of other diene polymerizations and other diamines. The observations suggest a more complex system than described above for styrene polymerization in presence of TMEDA, This result is clearly connected with the increased association number of uncomplexed diene living ends which permits a greater variety of complexes to be formed. 

In the present case, the electron hopping chemistry in the polymeric porphyrins is an especially rich topic because we can manipulate the axial coordination of the porphyrin, to learn how electron self exchange rates respond to axial coordination, and because we can compare the self exchange rates of the different redox couples of a given metallotetraphenylporphyrin polymer. To measure these chemical effects, and avoid potentially competing kinetic phenomena associated with mobilities of the electroneutrality-required counterions in the polymers, we chose a steady state measurement technique based on the sandwich electrode microstructure (19). 

Copolymers with sites for association in aqueous solutions were pre-pared by copolymerizing acrylamide with N-alkylacrylamides or with the ampholytic monomer pairs sodium 2-acrylamido 2 methylpro-panesulfonate (NaAMPS) and 2-acrylamido-2-methylpropane-dimethylammonium chloride (AMPDAC). The copolymers were characterized by elemental analysis, NMR and Fourier transform infrared spectroscopy, and lowhangle laser and quasielastic lightscattering measurements. Rheological properties were studied as a function of microstructure, molecular weight, polymer concentration, electrolyte concentration, and shear rate. On the basis of those results, a conceptual model that is based on microheterogeneous domain formation in aqueous solutions is proposed. 

Most concentrated structured liquids shown strong viscoelastic effects at small deformations, and their measurement is very useful as a physical probe of the microstructure. However at large deformations such as steady-state flow, the manifestation of viscoelastic effects—even from those systems that show a large linear effects—can be quite different. Polymer melts show strong non-linear viscoelastic effects (see chap. 14), as do concentrated polymer solutions of linear coils, but other liquids ranging from a highly branched polymer such as Carbopol, through to flocculated suspensions, show no overt elastic effects such as normal forces, extrudate swell or an increase in extensional viscosity with extension rate [1]. 

Microindentation with a point indenter, causing deformations on a very small scale, is one of the simplest ways to measure the mechanical properties of a material [64]. The method uses a diamond pyramid that penetrates the surface of a specimen upon application of a given load at constant rate for a given time (Figure 8). Because of its simplicity, microindentation has become a common technique to measure the micromechanical behavior of polymers and its correlation with microstructure [65,66], Microhardness, H, is obtained... 

A polymer chain is a permanent record of the statistical chain of events which constituted the polymerization process. From its microstructure, it is possible to identify the various monomer reactions modes, to measure their relative rates, and even — at least in principle — to infer their interdependence the longer the chain segment that can be examined, the richer is its message. 

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