Unconventional crosslinking of the blends of chlorosulfonated polyethylene
and carboxylated acrylonitrile-butadiene rubber
Polimery 2005, No 7-8, 587
Interpolymeric crosslinking of chlorosulfonated polyethylene/carboxylated acrylonitrile-butadiene rubber blends (CSM/XNBR) (Table 2) with MgO in the presence of stearic acid at temp. 433 K (160°C) for 30 min has been investigated. Effect of CSM containing various amounts of chlorine bonded (Table 1) on the properties of CSM/XNBR blends was studied as well. Extent of crosslinking was estimated on the basis of determinations of vulcametric torque (L) (Fig. 1), equilibrium swelling (Qv) in selected solvents and sol fraction content (fraction soluble in 2-butanone - S) (Tables 3 and 5). It was found that CSM did not undergo crosslinking in given conditions while in the blend with XNBR the interpolymeric reaction of both elastomers occurred. It was confirmed by bounded chlorine values, S and IR analysis (Fig. 2, Table 4). It was observed that degree of CSM bonding with the network depends on its type and content in the blend. Tensile strength (TSb), elongation at break (Eb) temperature dependence of dynamic loss tangent (tgd) and storage modulus (E) (Fig. 3) were determined using dynamic mechano-thermal analysis (DMTA) of cured CSM/XNBR blends. There were found ionic interpolymeric bonds of structure ~C-CO-O-+Mg+-O-SO2-C~ in cured CSM/XNBR blend [equations (1)-(3)] which gave the blend high mechanical strength and act as chemical compatibilizer.
Key words: chlorosulfonated polyethylene, carboxylated acrylonitrile-butadiene rubber, blends of elastomers, crosslinking, interpolymeric bonds, mechanical properties