Mastication behavior of cis-1,4-polyisoprene as a model for natural rubber

ABSTRACT The mastication behavior of synthetic cis‐1,4‐polyisoprene (IR), deproteinized natural rubber (DPNR), and natural rubber (NR) in an internal mixer has been investigated at mixing temperatures from 88 to 186°C and different levels of mechanical energy, using Mooney viscosity and size exclusion chromatography (SEC). An envelope‐shaped mastication efficiency curve and high similarity in the mastication behavior can be observed for IR and NR but not for DPNR. The minimum of the envelope‐shaped curve shifts to lower temperatures when the mechanical energy is increased. Based on these findings, a mathematical description for the contribution of mechanical and thermo‐oxidative mastication mechanisms has been established. Distinct statistical distribution of thermo‐oxidative scission can only be observed in SEC measurements of materials masticated at high temperatures over 170°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39989.