Structural changes of semicrystalline polyolefin block copolymer elastomers during step cycle mechanical processing

Development of stereo- and regioselective catalysts has led to the capability to produce multiblock copolymers with crystalline isotactic or syndiotactic polypropylene blocks and ethylene-r-propylene rubbery blocks which have excellent elastomeric properties. During step cycle mechanical processing the crystals can plastically deform and transform from lamellae into rod-like fibrils. The stress-strain tensile curves provide evidence of dramatic changes in the mechanical properties and small angle and wide angle X-ray scattering experiments as well as real space imaging bring a better understanding of the structural changes of the crystals during such processing.