Further Studies of the Infra-Red Absorption of Rubber

The transmission spectrum of natural rubber has been studied in the region between 1μ and 15μ and the effects of linear and radial stretch have been observed. Linear extension greater than 400 percent of the original length produces an increase in the C–C vibrational frequency. Both linear and radial stretch produce an increase in absorption coefficient and a decrease in reflection coefficient. The changes in absorption and reflection coefficients are greatest at short wave-lengths.