Rheological and curing properties of reactive blending products of epoxidised natural rubber and cassava starch

Epoxidised natural rubber ( ENR) has been prepared and used as a blending i ngredient together with a compatibiliser for blending of natural rubber lai r dry sheet, ADS) and cassava starch. Mooney viscosities of the blends were quantified at 100 degreesC and rheological properties in terms of shear st ress and shear viscosity were plotted against shear rates. The results show ed that pure ENR gave a lower Mooney viscosity, shear stress, and shear vis cosity than blends with cassava starch. Mooney viscosity, shear stress, and shear viscosity For the blends increased with increasing levels of starch. At the same level of cassava starch blended. the highest values of these q uantities were observed for the blends with ENR. The blend of ADS with ENR as a compatibiliser showed lower values than those of ENR itself, but highe r than those of ADS with the starch. The results are described in terms of the level of chemical interaction between polar groups in ENR and in cassav a starch. Curing behaviour for compounds of ENR. ADS. and ADS with ENR as c ompatibiliser were studied. The results found that ENR exhibited a long del ay (similar to 10 min) before the vulcanisation took place compared with 1 min for ADS compounds. In the curing curve for ENR, an equilibrium value at maximum torque was not found indicating that the stiffness of the ENR comp ounds still increased with increasing testing time until 60 min. Stiffness of the ENR compounds also increased with increasing levels of cassava of th e starch.