Interfacial Modification Of Multi-walled Carbon Nanotubes/Poly(ether Ketone) Nanocomposites

Poly(ether ketone)is one of the important varieties in the poly(aryl ether ketone)family.It has excellent wear resistance,corrosion resistance,heat resistance and high mechanical strength.It requires material in precision machinery,electronic components,and aerospace.Widely used in more demanding high-end technology fields.In recent years,in order to further improve material properties and expand its application range,research on the modification of poly(ether ketone)and its composite has become a research hotspot in the field of special engineering plastics.This thesis focuses on the research of multi-walled carbon nanotubes / poly(ether ketone)composites.In order to solve the problem that multi-walled carbon nanotubes are easy to agglomerate and disperse in the matrix,first a small molecular monomers modify multi-walled carbon nanotubes.Through the ?-? interaction between the multi-walled carbon nanotubes and the conjugated structure monomer,the surface of the multi-walled carbon nanotubes is entangled and covered,thereby weakening and blocking the interaction between the multi-walled carbon nanotubes and realizing its effectiveness of scattered.Poly(ether ketone)nanocomposites were then prepared by in-situ polymerization.In this way,not only can the multi-walled carbon nanotubes be further dispersed in the matrix,but also the interface binding ability of the two is improved,and the purpose of uniformly dispersing the multi-walled carbon nanotubes in the poly(ether ketone)matrix is improved,thereby improving the mechanical properties of the composite material.Based on the above ideas,the specific work of this paper is as follows: First,the common melt blending method is used to prepare poly(ether ketone)nanocomposites.The mechanical properties test showed that its tensile strength and elongation at break were lower than those of pure resin,and scanning electron microscope test found thatmulti-walled carbon nanotubes agglomerated in the poly(ether ketone)matrix.Therefore,we also tried to prepare multi-walled carbon nanotubes / poly(ether ketone)composites by conventional in-situ polymerization.This method can directly compound multi-walled carbon nanotubes into the reaction system for polymer production.During the reaction,the shearing effect of mechanical stirring of the reaction device,the adsorption of small molecules by the carbon tube,and the small molecules adsorbed due to The entanglement effect of the molecular chain growth brought about by the reaction promotes the dispersion of carbon nanotubes,and finally improves the mechanical properties of the composite material.The results of mechanical and scanning electron microscopy proved that in situ polymerization is an effective method for preparing multi-walled carbon nanotubes / poly(ether ketone)composites.On the basis of the above-mentioned good results obtained by in-situ polymerization,a series of poly(ether ketone)copolymers containing a large ?conjugated fluorene group in the main chain were further designed and synthesized.The effects of small ?-conjugated structures(1 ~ 10%)on the properties of poly(ether ketone)s were studied.The test results show that copolymers with a small amount of fluorene units not only exhibit good thermal stability and high-temperature dimensional stability,but also have excellent mechanical properties.When the content of the fluorene unit is 2%,the flexural strength of the copolymer is 149.3 MPa,which is 12% higher than that of pure PEK,and the impact strength is 54.6 J / m,which is30% higher than that of pure PEK.And its elongation at break is 91% higher than that of pure PEK,and it has greatly improved its strength and toughness compared to PEK resin.Through the above experiments,we determined the optimized copolymer composition,and obtained the important conclusion that the introduction of about 2%of bisphenol fluorene units in PEK is beneficial to improve the comprehensive strength and thermal performance of the resin..Guided by the above conclusions,we pre-dispersed multi-walled carbon nanotubes with a bisphenol fluorene monomer containing a large ? conjugated structure,and then directly added them to the poly(ether ketone)in situpolymerization system to prepare functionalized multi-walled carbon nanotube /poly(ether ketone)composites.The addition of only 1 ~ 2% carbon tube(bisphenol fluorene pre-dispersed)can increase the Tg of the composite material by about 10 ?compared with pure resin,and the tensile strength of the 2% pre-dispersed carbon tube / poly(ether ketone)composite material reaches 128.6 MPa,the bending strength reached 154.2 MPa,which is 14% and 16% higher than pure resin,respectively.And compared with the same content of undispersed carbon tube / poly(ether ketone)composite,its tensile and flexural strength were increased by 9% and 4%,respectively,and the elongation at break was increased by 167%.This shows that the bisphenol fluorene pre-dispersed carbon nanotube fillers have shown a good simultaneous strengthening and toughening effect in the modification of the poly(ether ketone)matrix.The scanning electron microscope comparative test found that the pre-dispersed multi-walled carbon nanotubes could be better dispersed in the matrix,and the interface between the multi-walled carbon nanotubes and the matrix was enhanced.