TETRAHYDROFURAN POLYMERIZATION INITIATED WITH HETEROPOLYACID Ⅴ. DETERMINATION OF CONCENTRATION OF PROPAGATING SPECIES AND CHAIN PROPAGATION RATE CONSTANT
Kinetic studies of tetrahydrofuran polymerization intiated by heteropolyacid showed that the concentration of propagating species maintained unchanged in the main period of the polymerization
indicating the absence of chain termination.The concentration of propagating species was measured by using a modified sodium phenoxide method and hydroxyl end-group analysis method
and it showed that each of the three protons in heteropolyacid initiated one chain.The same result was also verified for the acetic anhydride promoted system by the hydroxy end-group analysis method.The values of the chain propagation rate constant of THF polymerization at 0℃ and 20℃ were found to be 3.78×10-3and 1.98×10-2 L·mol·s1
respectively
which are in correspondence with the chain propagation rate constant of THF on ionic active species.