RESONANCE RAMAN-SPECTROSCOPIC STUDY OF AN IODINE-DOPED PSEUDO-INTERPENETRATING POLYMER NETWORK OF NATURAL RUBBER-POLY(CARBONATE URETHANE)

The resonance Raman (r.R.) spectra of two highly conducting, but disti nct, iodine-doped rubber samples, natural rubber (NR) and pseudo-inter penetrating polymer (PIPN) (NR with crosslinked polyurethane) have bee n investigated. Both systems with excessive iodine exhibit nearly indi stinguishable r.R. spectra, with well-resolved iodine modes in the low -frequency region, <1000cm(-1), and a nearly featureless spectrum in t he region of the polymer modes, >1000 cm(-1). When the excess iodine i s washed, the r.R. spectrum in the low-frequency range remains unchang ed, but the high-frequency region becomes distinct. NR exhibits enhanc ed polymer backbone modes, but the PIPNs retain featureless spectra. T hese findings suggest that energy transfer from iodine to the polymer backbone in the case of NR is evident, but no such path exists in the PIPN samples, i.e. different energy transfer paths are operational. (C ) 1997 Elsevier Science Ltd.