某些磺化乙丙橡胶离聚体的加工及力学性能

MELT FLOW AND MECHANICAL PROPERTIES OF SOME SULFONATED EPDM IONOMERS

The melt flow behavior and mechanical propedrties of the sulfonated EPDM ionomers neutralized with different divalent or bivalent cations , including transition metallic ions , as well as amines were studied .The ionomers were prepared through sulfonation of EPDM in petroleum ether solution using sulfuric acid and acetic anhydride as sulfonating agent , followed by neutralization with alcoholic solution of metallic salts or amines . The melt viscosity was represented by mixing torque value measured by Brabender Plasticorder with a shear rate of 30 r/min .Mechanical properties were measured on a XL-100 A Tensile Tester .The results showed that the amine neutralized ionomer can be processed much easier than metallic ion neutralized ionomer due to the higher ionic potential of the metallic ion . Torque value decreased with increasing neutralization degree . This can be explained by a change of ionic crosslinkage to ionic association .At neutralization degree of 1 molar ratio , torque value of ionomers neutralized with different metallic ions decreased in the following order :Cu2+>Ce3+>Ni2+>Pb2+In the case of ethylamine neutralized ionomer , with increasing amount of ionic plasticizer zinc stearate added , tensile strength and ultimate elongation increased at first and then decreased .while permanent set increased gradually .This is because ionic plasticizer can make the ionic domains of the ionomer distribute more uniformly , while excess ionic plasticizer merely acts as filler . More zinc stearate is needed in the case of lead ion neutralizedionomer than in the case of amine neutralized ionomer and the effect on increasing tensile strength is more obvious in the former case . The effect of lead stearate on increasing tensile strength of the ionomer is less effectivethan that of zinc stearate . The amine neutralized ionomer with sulfonation content below 0.14 mmol/g EPDM showed low tensile strength and large ultimate elongation and permanent set , similar to the unvulcanized EPDM rubber . The ionomer with sulfonate content above 0.25 mmol/g EPDM exhibited thermoplastic rubber behavior . The ionomer with neutralization degree at 1 molar ratio showed better mechanical properties than those with smaller or excess molar ratio , since excess amine inserts between ionic pairs and weakens the interaction . The tensile strength of the ionomers neutralized with different amines decreased in the following order : isopropyl amine > ethylamine >diethylamineThe sulfonated EPDM ionomer neutralized with differ ent amines can be processed without using ionic plastieizer . Although its tensile strength is lower than that of amine neutralized sulfonated IIR ionomer , its ultimate elongation is still high and permanent set very low .Tensile strength of the sulfonated EPDM ionomers neutralized with various metallic ions decreased in the following order :Pb2+>Cu2+ ,Ba2+ ,Co2+>Ni2+ ,Ce3+>Al3+