Macromolecular Rapid Communications, Vol.36, No.8, 744-749, 2015
Chemical Cross-linking of Polypropylenes Towards New Shape Memory Polymers
In this work, syndiotactic polypropylene (sPP) as well as isotactic polypropylene (iPP) are crosslinked to gain a shape memory effect. Both prepared PP networks exhibit maximum strains of 700%, stored strains of up to 680%, and recoveries of nearly 100%. While x-iPP is stable for many cycles, x-sPP ruptures after the first shape-memory cycle. It is shown by wide-angle X-ray scattering (WAXS) experiments that cross-linked iPP exhibits homoepitaxy in the temporary, stretched shape but in contrast to previous reports it contains a higher amount of daughter than mother crystals.