Preparation and properties of modified carbon fiber reinforced polyamide 6 composites

Abstract

The carbon fibers (CF) were surface modified by nitric acid treatment and polyamide 6 (PA6) solution sizing treatment, and a series of CF/PA6 composites with high strength and high modulus, low melting index, and excellent processability were prepared. Scanning electron microscope (SEM), differential scanning calorimeter (DSC) and melt index meter were used to test and characterize the microstructure, mechanical properties and crystallization behavior of the composite materials. The results show that a layer of PA6 film is formed on the surface CF after immersion and sizing treatment with PA6 solution,which greatly enhances the binding force between the fiber and PA6 matrix,and improves the dispersibility of CF. The overall strength and modulus of the composites are improved. The tensile strength of the CF/PA6 is increased by 80.8% and the elastic modulus is increased by 513.9% when the modified CF amount is 8% (mass fraction). The addition of modified CF can promote the transition of PA6 from the γ crystal form to a more stable α crystal form. At the same time, the crystallization temperature and crystallization rate of the composites are increased, so that the crystallization of the composites are more uniform, thereby reducing the melting index of the composite and improving its processing performance.

Keywords

• polyamide 6
• carbon fiber
• extrusion processing
• crystallization behavior