Characterization of the molecular structure of masticated natural rubber using rheological techniques

Mastication can improve the plasticity and reduce the molar mass of natural rubber (NR). The end product properties greatly depend on the efficiency of mastication. For NR before and after mastication, the changes in molecular properties are mainly attributed to the effects of mechanical and thermo-oxidative degradation. We investigated the variations in molecular weight, molecular weight distribution, degree of branching, and thermal stability of NR after mastication at 35, 75, and 110 rpm for 20 min. The results show that NR has a smaller molecular weight, broader molecular weight distribution, and a lower degree of structural branching at higher rotor speeds. Additionally, the rheological measurements were compared with gel permeation chromatography results, and the comparative outcomes reflect a strong correlation between these data. Rheological analysis reveals considerable complex relationships, and this measurement is more efficient, simple, and convenient than the other technique. Typical molecular changes due to natural rubber mastication.image