Preparation And Properties Of Polyamide 6/Functionalized Thermal Exfoliated Graphite Composites Through Ultrasonic-assisted Extrusion

The thermal exfoliated graphite(EG) was prepared and functionalized via strong acid, toluene diisocyanate(TDI) and ultrasonic vibration obtaining carboxyl functionalized thermal exfoliated graphite(A-EG), TDI functionalized thermal exfoliated graphite(T-EG)and ultrasonic functionalized thermal exfoliated graphite(u-EG). By using ultrasound-assisted extrusion means, the above-mentioned functionalized thermal exfoliated graphites were respectively melt blending with PA6 to prepare PA6/functionalized thermal exfoliated graphite composites. This paper mainly studied the effect of functionalized methods of EG, contents of EG and ultrasonic outfield on the structures and properties of PA6 matrix. The main conclusions are listed as follows:(1)The worm-like thermal exfoliated graphite was prepared with expandable graphite via quick thermal expansion. The one hand, the thermal exfoliated graphite was treated with acid mixtures of concentrated sulfuric acid and concentrated nitric. The product was treated with TDI solvent, which finally obtained chemical functionalized thermal exfoliated graphite. The other hand, the ultrasonic functionalized thermal exfoliated graphite was prepared when the thermal exfoliated graphite was treated with ultrasonic vibration. The results showed functional modification changed the morphology and structure of thermal exfoliated graphite,and-OH,-COOH and-NCO were successfully grafted onto the sheets of thermal exfoliated graphite.(2)PA6/chemical functionalized thermal exfoliated graphite composites were prepared by using ultrasound-assisted extrusion. The studies demonstrated: chemical functional modification improved the dispersion of thermal exfoliated graphite in the PA6 matrix.Chemical functionalized thermal exfoliated graphites obviously increased the mechanical ofPA6 composites. The best mechanical properties of PA6/chemical functionalized thermal exfoliated graphite composites appeared when the content of chemical functionalized thermal exfoliated graphite was 0.5wt%. The chemical functionalized thermal exfoliated graphite had significant effect on crystallization temperature, degree of crystallization, dynamic mechanical, heat resistance properties of PA6 composites. Ultrasonic-assisted melt extrusion could improve the mechanical, dynamic mechanical, crystallization, heat resistance properties of PA6/chemical functionalized thermal exfoliated graphite composites, to varying degrees.(3) PA6/ultrasonic functionalized thermal exfoliated graphite composite was prepared by using ultrasound-assisted extrusion. The results showed: ultrasonic functionalized thermal exfoliated graphite had a smaller size, and could disperse more uniform in the PA6 matrix.The addition of ultrasonic functionalized thermal exfoliated graphite effectively increased the mechanical properties of PA6 composites. The best mechanical properties of PA6/ultrasonic functionalized thermal exfoliated graphite composites appeared when the content of ultrasonic functionalized thermal exfoliated graphite was also 0.5wt%. Compared with PA6, the tensile strength and Young’s modulus were increased by 35.2% and 10.5%. The flexural strength and flexural modulus were increased by 29.9% and 38.2%. The ultrasonic functionalized thermal exfoliated graphite had significant effects on crystallization temperature, degree of crystallization, dynamic mechanical, heat resistance properties of PA6 composites..Ultrasonic-assisted melt extrusion could improve the dispersion of ultrasonic functionalized thermal exfoliated graphite and increase the mechanical, dynamic mechanical, crystallization,heat resistance properties of PA6/ultrasonic functionalized thermal exfoliated graphite composites, to varying degrees.