A study of conformationl transformations in guttapercha by infrared spectroscopy

The infrared spectra of crystalline - and -guttapercha, and also of molten guttapercha, were studied in the 400–1700 cm^–1 range. It is shown that the IR spectra of the two crystalline modifications exhibit marked differences. The absorption bands characterizing the crystalline - and -forms were determined. The crystalline bands were used to determine the melting points of the two forms. It is shown that stretching of the -form produces a more elongated rotational isomer, i. e., guttapercha; the -form is produced by recrystallization of the -form. The dichroism of the C=C valence vibrations observed in the spectrum of oriented guttapercha indicated that the molecular chains of the -form have a spiral conformation. Guttapercha, i. e., trans-polyisoprene exists in crystalline form at room temperature.