Preparation And Properties Of Toughened And Barrier Nylon 11 Composites

Polyamide 11(PA11)is a general engineering plastic with low density,high corrosion resistance,low water absorption and good dimensional stability.It has been widely used in aviation,automobiles,oil pipelines,gas engineering,etc.However,under certain circumstances,the barrier properties and mechanical properties of pure nylon 11 can not fully meet with the requirements.In this paper,PA11/EVOH composites were prepared by melting compounding ethylene-vinyl alcohol copolymer(EVOH)and PA11,and then melting compounding with modified montmorillonite(Mont)to prepare PA11/EVOH/Mont ternary composite.Their mechanical properties,morphology structure,barrier properties and rheological behavior were investigated by material mechanics properties,impact tester,scanning electron microscopy(SEM)and rheometer,respectively.The experimental results of barrier properties and mechanical properties showed that the oil-absorption reached the minimum value(0.16%,xylene),and impact strength was increased up to 23.857 KJ/m2in the case of PA11/EVOH=75/25.In comparison with that of the PA11,the barrier property,impact strength of the PA11/EVOH composites were increased 500%and 24.9%,respectively.SEM micrographs showed that the compatibility of EVOH with PA11 was better with the increase of EVOH content.When the ratio of the ternary composite was PA11/EVOH/Mont=75/25/10,the oil absorption reached 0.19%(xylene),and the impact strength was increased up to 30.24 KJ/m2.In comparison with that of the neat PA11,the barrier property,impact strength of the PAll/EVOH/Mont composites were increased 430%and 58.3%,respectively.SEM images showed that Mont can be uniformly distributed in PA11/EVOH with the Mont content increasing.The rheological behavior of PA11/EVOH and PA11/EVOH/Mont composites was investigated.The results showed that PA11/EVOH and PA11/EVOH/Mont were pseudo-plastic and exhibited shear-thinning.The non-Newtonian indexes(n)decreased with the addition of EVOH,which indicated that the sensitivity of composite to shear rate increased.With the increase of EVOH content,the storage modulus(G'),loss modulus(G�)and complex viscosity(?*)of PA11/EVOH composites increased and then decreased,the viscoelastic properties of composite had been improved.The tan? all above were lower than pure PA11.Composite recovery was better than PA11.When Mont was added,the n,G',G�and ?*were not significantly correlated with Mont content.However,the tan? all above were lower than PA 11/EVOH,and the composite recovery was further improved.These research results will lay a foundation for the development of low cost and high barrier nylon composites.