Determination of Crosslink Density of a Rubber Component of Thermoplastic Vulcanisates

Crosslink density is one of the most important parameters of elastomers including thermoplastic vulcanizates (TPV). So far, only few methods have been available for its determination. For conventional elastomers, equilibrium swelling measurements, mechanical tensile tests in combination with the Mooney-Rivlin-plots and NMR have been used for this purpose. Due to the more complex morphological structure of TPV, tensile tests as well as NMR have not been suitable in terms of crosslink density of TPV or have a limited use. Recently, the temperature scanning stress relaxation (TSSR) was used to determine the crosslink density of the TPV rubber phase. However, this is a rather complicated method. For these reasons, the limited swelling method has been examined. The obtained results are in a good accordance with those of the TSSR method.