Preparation And Mechanical Properties Of Nano Alumina/carbon Fiber Multi-scale Reinforced Polyamide Composites

Fiber reinforced thermoplastic resin matrix composite attracts more and more interest because of its excellent mechanical properties and easier recycle.Multi-scale enhancement to further optimize its mechanical properties has become a research hotspot.Laminated film compression-molding was used to fabricate carbon fiber/nano alumina multi-scale reinforced PA6 matrix composite(CFF/Al2O3/PA6).The effect of preparation technology of prepreg,molding technology and nano-Al2O3 content on the properties of nano CFF/Al2O3/PA6 laminates were investigated by FESEM?TGA-DSC and flourier transformation infrared spectroscopy(FTIR).The results as follows:(1)The coating on the surface of CFF can be effectively removed after infiltrating CFF 24 h in formic acid solution;a good prepreg can be obtained after CFF was infiltrated by 4wt% PA6/formic acid solution for 24 h.(2)The carbon fiber reinforced PA6 matrix composite(CFF/PA6)laminates were fabricated by laminated film compression-molding to study the effects of molding temperature,molding pressure and holding time on the mechanical properties of CFF / PA6 laminates.The optimized molding process parameters are as follows: the prepressure was 1MPa and keep 10 min,and then the pressure was increased to the full pressure 3MPa and keep 15 min.The pre mold temperature was 180?,the molding temperature was 230?.The flexural strength,interlaminar shear strength and impact strength of CFF/PA6 laminates were 250.3MPa,87.6MPa,56.1MPa respectively.(3)With the increase of nano-Al2O3 content in the PA6 matrix,the flexural strength and impact strength of CFF/Al2O3/PA6 laminates firstly increased and then decreased.When the nano-Al2O3 content reached to 6wt%,the corresponding mechanical strength of CFF/Al2O3/PA6 laminates reached peak values,but the interlaminar shear strength decreased obviously.From the microscopic view of SEM,it can be seen that nano-Al2O3 exhibits different degrees of agglomeration.This showed that the reasonable amount of nano-Al2O3 can obviously improve the mechanical properties of CFF/Al2O3/PA6 laminates,but nano-Al2O3 was unfavorable to the interlaminar shear properties of laminates,this is related to the agglomeration of nanoparticles.(4)The addition of nano-Al2O3 particles can significantly improve the mechanical properties of composite laminates.When the nano-Al2O3 content in the matrix reached to 6wt%,flexural strength and vertical impact strength are 387.6MPa,80.3MPa,which increased by 54.8% and 94.9%,respectively,when compared with CFF / PA6 laminate.