Polymer number-average molecular weight

On the other hand the kinetic methods suffer from experimental error connected with the evaluation of the polymer number average molecular weight. Moreover, if the kinetics are not steady from the initial moments of polymerization, the latter... 

Polymer Number-Average Molecular Weight, M (x KF3) Styrene-to-Rubber Ratio (wt/wt) Yield Stress, Vy (MPa) Engineering Fracture Stress, Vf,e,mrg (MPa) Fracture Stress, (Tf(MPa) Fracture Strain, f(%)... 

One final area for discussion is the use of NMR for the determination of polymer number average molecular weights. End group resonances were clearly visible in the 13c NMR spectrum of the ethylene-l-hexene copolymer in Figure 3. An opportunity to determine polymer degrees of polymerization or number average molecular weights should not be overlooked. 

The activity of CALB immobilized on resins 1 to 4 (see Table 1) was assessed by s-CL ring-opening polymerizations. All immobilized resins have similar CALB loading (5.1 to 5.7 %-by-wt) and water content (1.4 to 1.9%). As shown previously , different chemical shifts are observed for methylene protons (-OC//2-) of e-CL monomer, PCL internal repeat units and chain terminal -012-OH moities. Hence, by in situ NMR monitoring, monomer conversion and polymer number average molecular weight (A/ ) were determined. 

Molecular sieve type and size Re- action time (days) Stirring Unreacted iso- butylene Yield of polymer % Number average molecular weight Mn We t average molecular weight Mw... 

These values were used to calibrate GPC colunms for the polymer. Number-average molecular weights determined with modified calibration curves agreed well with those determined by embulliometry. The value of 0.96 for a was consistent with the idea that poly(3-alkylthiophene)s formed relatively stiff polymer chains in solutions. 

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