Morphology of nylon 1212 toughened with a maleated EPDM rubber

摘要

BACKGROUND:Polyamides,or nylons,are an attractive class of engineering polymers due to their excellent strength and stiffness,low friction and chemical and wear resistance.However,they are highly notch-sensitive,i.e.they are often ductile in the un-notched state,but fail in a brittle manner when notched.A super-tough nylon 1212 was prepared by blending nylon 1212 with ethylene propylene diene monomer(EPDM)grafted with maleic anhydride(MA).The morphologies of Izod impact fracture surfaces as well as xylene-etched surfaces of the nylon were thoroughly investigated using scanning electron microscopy(SEM).RESULTS:The fracture morphology and the impact strength of the nylon 1212 blends are very well correlated.The impact fracture surface of the blends exhibits certain characteristic features,such as the observation of fiber-like sticks when etched with boiling xylene,formed during the impact fracture process.SEM images of xylene-etched surfaces as well as the results of X-ray energy dispersive spectroscopy suggest that the successful toughening of nylon 1212 with EPDM-graft-MA is due to the reaction between the anhydride of EPDM-graft-MA and the amine end-groups of nylon 1212,leading to the formation of a homogenous graft copolymer system.CONCLUSION:The copolymer system,acting as a surfactant,reduces the interfacial tension between nylon 1212 and EPDM-graft-MA and produces a highly compatible super-tough nylon 1212.