Characterization of polyisobutylene (PIB)-polybutylene terephthalate (PBT) multiblock. copolymers by thermally stimulated discharge (TSD) current and dynamic mechanical analysis (DMA) methods is described. Both the length of the PIE segments (2200-10000 g/mol), and the overall composition (30-80 wt %) of the multiblock copolymers were varied. Both methods support the block. structure of the multiblock copolymers investigated. Despite the apolar nature of the PIE segments, they proved to be detectable by the TSD method. The relaxation times and the mobility of the chain length were also determined.