Preparation And Characterization Of Functional Nylon 6 Composites

Polyamide 6(PA6)is a thermoplastic with good processability and chemical resistance,which is widely used in engineering plastic films and fibers.However,due to its small elastic modulus,easy deformation in use and poor thermal conductivity and heat resistance,PA6 has limited its application in mechanical.electronic,architectural,textile and packaging industries.In this paper,the modified nylon 6 was filled with micro-nano carbon materials.The effects of different micro-nano carbon materials on the thermal conductivity,the other functions and properties of nylon 6 composites were studied.Meanwhile,the effects of the combined filling and surface modification of nano-carbon materials on the surface coating properties of nylon 6 fabric were also studied.(1)EG/PA6,CF/PA6 and CF/EG/PA6 thermal conductive composites were prepared with nylon6(PA6)as a matrix and carbon fiber(CF),expanded graphite(EG)as the thermal conductive filler by melt-mixing.Fixed the filling content of 40wt%,the effects of different ratios of CF to EG on the contact mode between CF and EG,and the thermal conductivity and mechanical properties of CF/EG/PA6 composites were studied.The results indicate that the addition of EG is beneficial to increase of the thermal conductivity compared to single CF filling;When the CF/EG mass ratio is 25/15,the thermal conductivity of reach 2.554W/(m·K),which is 7 times higher than that of PA6.the tensile strength is increased by 125.34%,the flexual strength is increased by 119.8%,and the heat resistance demonstrates excellent.The SEM results show that fibrous CF and worm-like EG can form a three-dimensional network structure with "Terms contact" under the appropriate filling ratio.The three-dimensional network structure not only significantly increases the thermal conductivity of the composite,but also significantly improves the mechanical and thermal properties of the composite.It provides a new idea for the development of filled thermally conductive polymer materials.(2)The calcium carbonate-loaded graphene nanosheets were blended with nylon 6 to obtain the nyl6 masterbatch of graphene,and nylon 6 fibers with different graphene nanosheet contents were prepared by melt spinning.The morphology,mechanical properties and crystallization properties of graphene-modified nylon 6 fibers were investigated by field emission scanning electron microscopy,optical microscopy,differential scanning calorimeter,and fiber strength tensile tester.The results show that the surface of nylon 6 fiber with 0.1 wt%GNPs and 0.25wt%GNPs is smooth and flat,compared with pure nylon 6 fiber,the crystallization temperature and crystallinity of modified nylon 6 fiber are improved;the tensile strength of modified nylon 6 fiber decreased slightly,and the elongation at break increased significantly.Moreover,the addition of GNPs endowed nylon 6 fiber with anti-ultraviolet and bacteriostatic functions,the ultraviolet transmission rate in the long band is reduced by about 40%,and the inhibition rate against Staphylococcus aureus was 99.5%,the inhibition rate against Klebsiella pneumoniae can reach 86.3%(3)The self-crosslinking surface modifier TSiPD was used to improve the dispersion and interfacial compatibility of graphene nanosheets and carbon nanotubes in the coating resin matrix The thermal conductive and anticorrosive coating materials of organosilicon modified acrylic acid nano-composite were prepared by using the surface modified graphene nano-sheet and the aqueous dispersion of carbon nanotubes as additives.The Young's modulus fluctuation curve measured by the nanoindentation technique shows that the surface-modified filler can be uniformly dispersed in the matrix and the resin can wrap the filler.Through the characterization of the thermal conductivity,adhesion,corrosion resistance and microstructure of the coating,the results show that the thermal conductivity of the composite coating is not only related to the three-dimensional network structure formed by two different dimensional thermal conductive materials,but also closely related to the interfacial thermal resistance formed by filler and coating matrix.After the surface modification of the filler,the through-plane direction thermal conductivity of the 9.9wt%tGNPs+O.lwt%tCNTs composite coating reaches 2.9725 W/(m·K),while the coating adhesion level is 0.Moreover,the anti-corrosion performance of the coating is also improved.