Effects of temperature on the infra-red spectrum of partially crystalline trans-1,4-polyisoprene

Fourier-transform infra-red spectra were taken for semicrystalline solution-crystallized trans-1,4-polyisoprene at various temperatures from −145°C to the melting temperature (60–65°C) and in the melt to 110°C. Changes were followed by use of difference spectra. A decrease in amorphous content with decreasing temperature down to about −30°C and an increase in this parameter with temperature to 60°C were followed quantitatively. Crystal-field splitting of a CH 2 scissoring band was observed at −145°C. Changes in conformationally sensitive amorphous bands at temperatures above 65°C were used for tentative assignment of components of these bands.