Study On Composition-Morphology-Properties Of PA6/Polyolefins Alloys

PA6 is both a kind of excellent engineering plastics and a desirable packaging material. It plays an important role in the field of packaging because of its good mechanical, broad using temperature, oil resistance and barrier properties. However, PA6 film is not soft and flexible enough for some specified packaging purpose. Therefore, three systems were studied by adding soft polyolefins to polyamide in this paper. They are PA6/POE-g-MAH, PA6/EVA and PA6/POE/EAA blends respectively.The addition of POE-g-MAH into PA6 gave PA6/POE-g-MAH alloys in a twin-screw extruder. The Izod impact test showed that the increase of POE-g-MAH caused the impact strength to jump significantly, and when POE-g-MAH was 20 wt%, impact strength was about 13times that of pure PA6. Tensile strength, tensile yield stress, bend strength and bend elastic modulus of the blends went down apparently with the increase of POE-g-MAH, so the softness and flexibility of PA6 was improved greatly.Soft EVA (ethylene-vinyl acetate copolymer) was often used to improve softness of polymers. PA6/EVA blends was achieved by blending PA6 with EVA. The results indicated that the Increase of EVA made tensile strength, tensile yield stress and tensile modulus decline obviously, yield strain and elongation at breakage increase, but Izod impact strength didn't show large change.It was the first time in this paper that PA6/POE/EAA alloys were prepared to achieve nylon film which was free of toxicity and had good comprehensive properties. The results demonstrated that EAA was aneffective compatibilizer for the blends of PA6 and POE. Addition of EAA resulted in a finer dispersed POE particles and a good size distribution. Mechanical properties and processing performance were improved greatly around the range of 0-4 phr EAA. However, each property didn't show much change when EAA increasing to about 4 phr, that is to say, when the ratio of PA6 and POE was fixed at 85:15 by weight and EAA is 4 parts per 100 parts PA6/POE(85/15) by weight the compatibilization of EAA for PA6/POE approached to a critical point and the comprehensive property of the system reached to the best situation. Acid content of EAA influenced compatibility effect to some extent. When Acid content of EAA increased from 9% to 11%, the impact strength rose. Tensile strength, tensile yield stress, bend strength and bend elastic modulus of the blends went down. But all of these properties changed mildly. POE content of PA6/POE/EAA also had a large influence on properties of the alloys. The SEM photographs of PA6/POE/EAA blends showed that increasing POE content produced coarser breakage surface; the Izod impact strength was enhanced, and tensile strength, tensile yield stress, bend strength and bend elastic modulus declined with the increase of POE. The rheological test indicated that more POE led to a lower viscosity and therefore improved processing performance. However, when POE content rose to 20%, the viscosity of the alloys didn't decline at the same shear rate an)' more. In the end an optimal formulation of PA6/POE/EAA alloy was achieved for nylon film which was soft and flexible and far away from toxicity.