ISSN:
1573-8647
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract The infrared spectra of crystalline α- and β-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 α- and β-forms were determined. The crystalline bands were used to determine the melting points of the two forms. It is shown that stretching of the α-form produces a more elongated rotational isomer, i. e., β guttapercha; the β-form is produced by recrystallization of the α-form. The dichroism of the C=C valence vibrations observed in the spectrum of oriented guttapercha indicated that the molecular chains of the β-form have a spiral conformation. Guttapercha, i. e., trans-polyisoprene $$\left[ {\begin{array}{*{20}c} {} & {{\text{H}}_{\text{3}} {\text{C}}} & {} & {} & {} & {{\text{CH}}_{\text{2}} } & {} \\ {} & {} & {} & {} & {} & {} & {} \\ {} & {} & {} & {{\text{C = C}}} & {} & {} & {} \\ {} & {} & {} & {} & {} & {} & {} \\ {} & {{\text{H}}_{\text{2}} {\text{C}}} & {} & {} & {} & {\text{H}} & {} \\ \end{array} } \right]_n $$ exists in crystalline form at room temperature.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00617420
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