Raman longitudinal acoustic mode (LAM) studies of folded‐chain morphology in poly(ethylene oxide) (PEO). II. Normal mode analysis of folded‐chain structures of PEO

Normal mode calculations were carried out on model folded‐chain molecules to determine the effect of a fold on the LAM of PEO. The presence of a chain fold results in a decrease in the LAM frequency and intensity, the change in frequency being very much smaller than the change in intensity. End interactions do not seem to have much effect on the LAM when a fold is present at the chain ends. The effective chain length for determining the LAM frequency was found to be that part of the chain experiencing interchain interactions.