The influence of extrusion process on micromorphology of PA 6/POE/POE-g-MA ternary blends: A quantitative analysis

Abstract

The impact strength of nylon 6 (polyamide 6) can be improved by blending impact strength modifier at ambient temperature and then the applications of nylon 6 can be expanded widely. Polyamide (6) PA 6/poly(ethylene-1-octene) elastomer (POE)/poly(ethylene-1-octene) elastomer grafted by maleic anhydride (POE-g-MA) ternary blends were prepared in corotating twin-screw extruder by two kinds of extrusion processes, more than 10-fold increase of impact strength at ambient temperature was obtained from impact test of specimens, not at much expense of tensile properties. The influence of extrusion process, that is, one- and two-step extrusion, on the micromorphology of toughing nylon 6 blends was investigated systematically. Scanning electron microscopy was used to observe the fracture surfaces of bars prepared by injection-molding machine. In addition to particle size and distribution, interparticle distance ( τ) between neighboring dispersed phase particles in PA6/POE-g-MA/POE ternary blends was calculated and used to characterize the micromorphology. Supertoughness was obtained in both ternary blends, and the interparticle distances ( τ) were 0.228 and 0.179 µm, respectively, which were less than the critical τ c (0.3 µm) in nylon/rubber blends. The results showed that more homogeneous distribution of POE phase in nylon 6 matrix was found in blends prepared by two-step extrusion method, in which the average particle size of POE phase was 0.313 µm, while the average particle size in blends prepared by one-step method was 0.399 µm. The half-peak width of Gaussian distribution curve of particle size in blends prepared by one-step extrusion method was 0.278, which is higher than that of blends prepared by two-step method with the value of 0.248.