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.
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