End-group contents of poly

Table 14.2. End-Group Contents of Poly(Amic Acid)s Synthesized from Perfluorinated Diamines and 6FDA Dianhydride...

Carboxyl end group contents of poly(lactide) were determined by a dye interaction technique proposed by Palit and Mandal (21). A dilute solution of the polymer in benzene is reacted with a dilute benzene solution of a basic dye (e.g., Rhodamine 6G) in its unionized basic... 

The chemistry of the solid-state polycondensation process is the same as that of melt-phase poly condensation. Most important are the transesterification/glycolysis and esterification/hydrolysis reactions, particularly, if the polymer has a high water concentration. Due to the low content of hydroxyl end groups, only minor amounts of DEG are formed and the thermal degradation of polymer chains is insignificant at the low temperatures of the SSP process. 

Fig. 9. Transient absorption spectra observed at ambient temperature on pulse radiolysis of MTHF solution containing 5 base-m mol dm " 3 poly(4-vinylbiphenyl-co-l-vinylpyrene). The content of pyrenyl group is 0.15% against the total number of the side groups. (O) pulse end ( ) 0.2 ps after a pulse (T1) 1.4 ps after a pulse [60]...

The end-groups and in-chain defects in poly(vinyl alcohol) have been studied thoroughly.133-138 The number of 1,2-glycol units can be determined by 13 136-138 ancj i jj nmR138 spectroscopy. The 1,2-glycol unit at the chain end is distinguished from that in the chain by the 500-MHz 3H NMR spectrum. The analysis for the polymer obtained from poly(vinyl acetate) prepared at 60°C indicates that the contents of the end-chain and in-chain 1,2-glycol units are 0.06 and 1.7 mol %. This means that chain transfer from the primary radicals occurs every 50 times of head addition.135... 

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