Selected properties of elastoionomers prepared by reactive processing
Polimery 2005, No 9, 663
Ethylene-propylene and ethylene-propylene-diene rubbers functionalized with carboxyl groups were prepared. Unsaturated dicarboxylic acids incapable of homopolymerizing and their selected derivatives were used as functionalizing monomers. Functionalization was carried out by reactive processing in plasticized state and in properly chosen conditions of temperature and concentrations of a modifier and radical initiator. It was found that the best functionalization result, determined by alkalimetry and IR analysis, was reached when monophenylmaleamide was used (Fig. 1 and 2). Content of carboxylic groups bonded to polymer chains was in this case 8-40 mmol/100 g. Carboxylated rubbers obtained are susceptible to curing with zinc oxide (Table 2, Fig. 5). Cured rubbers show better tensile strength (up to 5 MPa) than non-cured ones (about 2.5 MPa) (Fig. 6). Crosslinks forming as a result of curing with metal oxides, show ionic structure and undergo cleavage under the influence of action of toluene-pyridine mixture or 3% solution of hydrochloric acid in toluene.
Key words: elastoionomers, ethylene-propylene elastomers, ethylene-propylene-diene elastomers, reactive processing, functionalization, carboxyl groups, IR, mechanical properties