Conference paper: A homologous series of diamine and bismaleimide cross-linkers are used to cross-link maleic-anhydridegrafted EPM irreversibly and furan-modified EPM rubbers thermoreversibly, respectively. The rubber properties of the cross-linked samples are shown to be dependent on the flexibility of the different spacers (aromatic and aliphatic spacers of different lengths) in the cross-linker.