| Abstract
| - Isobutylene (IB) polymerization kinetics were monitoredin real time using mid-infraredFTIR-ATR spectroscopy, with a diamond-composite insertion probe andlight conduit technology.Polymerization was initiated using the5-tert-butyl-1,3-bis(2-chloro-2-propyl)benzene(t-Bu-m-DCC)/2,4-dimethylpyridine (DMP)/TiCl4 (1:2:20) system inhexane/methyl chloride (60:40 v/v) cosolvents at −80°C, with [t-Bu-m-DCC] = 1.90 ×10-3 M and [IB]0 = 1.0 M. Monomerconcentration as a function of timewas obtained by monitoring the absorbance at 887 cm-1associated with the CH2 wag of IB. Thecalculated apparent first-order rate constant of 8.4 ×10-4 s-1 was within 3% of the valuedeterminedfrom traditional gravimetric methods (8.6 × 10-4s-1) withing the same range of conversion.Inspectionof the first-order plot generated from the FTIR data revealed a numberof deviations from linearity,which were attributed primarily to a transient rise and subsequent fallin reactor temperature causedby the initial large exotherm of polymerization. An artifactassociated with the method of data analysiswas also identified. These small differences in instantaneous ratewere not detected by the gravimetricmethod due to insufficient accuracy and density of datapoints.
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