Degradation of Natural Rubber and Deproteinized Natural Rubber

Abstract

Degradation of natural rubber and deproteinized natural rubber (DPNR) at 70 °C and 150 °C for 24 hours was investigated. Natural rubber was degraded at 150 °C to produce blown viscous liquid, whereas pale yellow rubber was covered with black brittle rind after degradation of DPNR at 150 °C. FT-IR, ¹H-NMR and ¹³C-NMR measurements of degraded natural rubber revealed that the functional groups formed by the reaction with oxygen radical and hydroxyl radical were introduced into natural rubber. In contrast, trans-1,4-isoprene unit and vinyl group were formed by the degradation of DPNR, suggesting that the degradation of DPNR occurred in the absence of oxygen and water. The difference between degradation of natural rubber and DPNR was attributed to the existence of protein to provide oxygen and water.