Thermoplastic elastomer (TPE) produced by dynamic vulcanization which is one of the reactive processing is generally called thermoplastic vulcanization (TPV).
It is considered that, in the mixing process of TPV, the crosslinke reaction and the EPDM dispersion in PP proceeds simultaneously. Therefore, the phase structure of TPV is complex and it is very difficult to analyze the kneading states. Since the slight difference of kneading states is known to lead to the large differences in the physical properties such as the extrusion processability and the surface appearance of the products, the conventional and exact testing methods to estimate TPV kneading state is required at TPV mixing plant.
It was found that an apparent activation energy (Ea) calculated from the temperature dependence of dynamic viscosity modulus is an effective index for measuring the degree of crosslink. Also the degree of EPDM dispersion was quantified by dynamic elasticity modulus change ratio (Gr) between G* at the strain of 20% and 1%. These indices can be calculated simply and easily from dynamic viscoelastic results and can be applied to estimate the kneading state of the TPV compound.