Infrared spectra of cis and trans isomers of poly(1,4‐cyclohexylenedimethylene terephthalate)

Infrared spectra have been recorded for cis and trans isomers of poly (1,4‐cyclohexylenedimethylene terephthalate) (PCHDT). Infrared dichroisms were determined and band assignments were made. From spectra of polymers in both the crystalline and amorphous phases it was determined that the crystalline bands for trans ‐PCHDT are virtually the same as those for poly(ethylene terephthalate) (PET), while cis ‐PCHDT showed very little change in its spectrum upon a change in phase. The same was found to be true of model compounds of PCHDT and PET. Of the series of compounds—ethylene glycol dibenzoate, 1,3‐propanediol dibenzoate, and 1,6‐hexanediol dibenzoate— the first two compounds exhibited the same crystalline bands as the PET and trans ‐PCHDT polymers, but 1,6‐hexanediol dibenzoate showed that the crystalline bands were shifted for the longer glycol chain. It was concluded that not only are the crystalline bands associated with the ‐OCC 6 H 4 CO‐ framework of these molecules but they also depend on the rigidity of the esterifying groups or glycol chain segments.