Preparation And Properties Of Polyetheretherketone Composite Powder

Polyetheretherketone?PEEK?is a high temperature resistant,semi-crystalline polymer.PEEK combines a good strength and stiffness with excellent thermal stability.Owning to their noticeable mechanical and thermal properties,Carbon fibers?CF?and carbon nanotubes?CNT?are used for reinforcements for polymer composites.However,CF and CNT both have poor interfacial compatibility with polymer matrix because their surfaces are no-polar with inert structures and lack active functional groups.In order to improve the mechanical and thermal performances of composites,we use surface modification to improve CF and CNT surface and compatibility between reinforcements and PEEK matrix.Selective Laser Sintering?SLS?,as a new 3D print manufacturing technology,has a unique advantage compared with traditional methods.Therefore,it has a valuable application to develop high strength and heat resistant composite powder materials suitable for SLS.PEEK powder was modified by heat treatment.The microscopic morphology,apparent density,average particle size of PEEK powder and mechanical properties of PEEK samples were investigated in this paper.The result showed that with the increase of time and temperature of heat treatments,the tensile strength,impact strength,bending strength and bending modulus of PEEK maintained a good status.The regularity of PEEK powder was relatively improved compared with commercially available PEEK.The apparent density of modified PEEK powder increased by 52%.The average particle size was close to 50?m.This morphology of PEEK powder was better suitable for SLS.Carbon fiber was modified by thermal oxidation,concentrated HNO₃ and concentrated HNO3/H2SO4.The PEEK/CF composites with 5wt%,10wt%,20wt%,30wt%,40wt%and 50wt%CF were prepared by compression molding.The mechanical and thermal properties of composites modified by different treatments were tested in this paper.The result indicated that the active groups on the surface of CF treated by acid modification increased and the surface activity improved.The mechanical and thermal properties of composites modified by thermal oxidation and concentrated HNO₃ modification were better.The optimum time of concentrated HNO₃ modification was 1 hour and the optimum temperature of thermal oxidation was 700?.The tensile strength,bending strength,bending modulus,thermal deformation temperature and vicat softening temperature monotonously increased,but the impact strength monotonously decreased with the increase of CF mass fraction.When CF mass fraction was 30wt%,PEEK/CF composites had good comprehensive performances.Multiple-walled carbon nanotubes were modified by lauryl sodium sulfate,concentrated HNO₃ and concentrated HNO₃/H₂SO₄.The composites with 0.25wt%,0.5wt%,1wt%,2wt%,4wt%,6wt%MWCNTs were also prepared by compression molding.The mechanical and thermal properties of composites modified by different modifications were studied in this paper.The result showed that the active groups increased on the surface of MWCNTs modified by acid modification and the surface activity improved.The mechanical and thermal properties of composites modified by sufactant were better.With the increase of MWCNT mass fraction,The tensile strength,impact strength,bending strength,bending modulus,thermal deformation temperature and vicat softening temperature all improved.When MWCNT content was 4wt%,the parameters above was the maximum.The agglomeration of modified MWCNTs in the matrix was weakened and the interfacial binding strength and interfacial compatibility were relatively improved.