Vibrational spectra and normal coordinate analysis of trans‐1,4‐poly(2,3‐dimethylbutadiene) and the two polymorphic forms of trans‐1,4‐poly(isoprene)

The infrared and Raman spectra of the two polymorphic forms of trans‐1,4‐poly(isoprene) (TPI) and trans‐1,4‐poly(2,3‐dimethyl butadiene) (TPDMB) are presented. Infrared spectra of the alpha and beta forms of TPI were obtained by digitally subtracting the amorphous contribution from the corresponding spectra of semicrystalline TPI polymers. Normal coordinate calculations are presented for both polymorphic forms of TPI and TPDMB, and the assignments of the normal modes are discussed.