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Summary
Reversible polymer networks combine mechanical properties of thermosets with the processability and recyclability of thermoplastics. The Diels-Alder (DA) equilibrium, in particular the furan/maleimide addition, represents the most promising approach to introduce reversibility into a polymer network. In this work three furan-modified polymers were combined into binary blends and then crosslinked with an aromatic bismaleimide through DA chemistry in order to extend their mechanical properties respect to the neat crosslinked polymers.
Notably, in Chapter 1 a furan functionalized ethylene-propylene rubber (EPM-Fu) was blended (up to 20%) with a furan functionalized polyketone (PK-Fu) and crosslinked. FT-IR and DSC analyses proved the reversible interaction between PK-Fu and EPM-Fu with the bismaleimide. Likewise, thermo-mechanical measurements (DMTA) indicated the re-workability of the material with no evident differences in elastic and loss modulus after several heating cycles and recycling procedures. A two-fold increase in Izod impact strength compared to the neat crosslinked polyketone was also recorded proving the toughening effect of the rubber. Analogously, in Chapter 2 the EPM-Fu rubber was blended with a furan modified biobased polyester and crosslinked. Thermal and mechanical reversibility, recyclability were proven by DSC and DMTA. A considerable toughening effect of the rubber was recorded, with negligible effect on the storage modulus. In Chapter 3 polyketones with different degree of furan modification were blended the EPM-Fu (up to 10%) and crosslinked. Reversibility was proven by DMTA. Swelling tests showed that higher furan intakes of PK-Fu lead to higher crosslink densities. Mechanical properties as Young modulus, compression set, hardness were determined and found to monotonously increase with the crosslink density.
