Interfacial Modification Of Multiwalled Carbon Nanotubes/Poly(Ether Ether Ketone) Nanocomposites With Poly(Aryl Ether Ketone)s Contained Carbazole Or Naphthalene Units

Polyether ether ketone?PEEK?is an important special engineering plastic,due to its high heat resistance,great mechanical properties,excellent solvent resistance,and other excellent properties.To date,it is widely used in aerospace,precision machinery,automobile,electronic components,medical devices,and some civil technical fields.In recent years,in order to further improve the performance of PEEK,PEEK based composites blending with some high-performance materials have been paid more and more attentions.Particularly nano materials,such as carbon nano tubes?CNTs?.By combining the properties form each component,the PEEK based composite blending with CNTs can be endowed with more properties,such as optical property,electrical property,magnetic property,and so on.In this thesis,my work focused on the PEEK based composite blending with CNTs.As well known,difficult dispersion and easy agglomeration are the key problems for blending CNTs into PEEK matrix.To solve the problems,we proposed that modified CNTs by polymer aryl ether ketone?PAEK?containing bulk conjugated structure units.These type polymers can disperse and coat multiwalled carbon nanotubes?MWNTs?effectively.This result leads to modified CNTs keep dispersed state well.To prove this theory,a series novel of carbazole-based PAEKs was synthesized and applied in this experiment.The results show that this type polymer can disperse and coat well,the dispersive capacity reached to 416 mg/L in CHCl₃.In further,a triphenylamine-carbazole based PAEK?PAK-Cz?was applied in my work in order to improve the thermostability and simplify synthetic procedures of modified MWNTs.The research results exhibited polymer PAK-Cz also can disperse and coat multiwalled carbon nanotubes?MWNTs?effectively,and the dispersive capacity reached 608 mg/L in NMP.By using this modified MWNTs,the tensile strength and flexural strength of MWNTs/PEEK composites can be improved to 98.5MPa and 148.2 MPa respectively,while the weight percent of MWNTs is only 5%in the whole composite.For further improve the thermostability of naphthalene based PAEK was applied in my work.Although the conjugation structure size of naphthalene is smaller than carbazole unit,the polymer naphthalene based PAEK also dispersed and coated multiwalled carbon nanotubes?MWNTs?well,and the dispersive capacity was 519mg/L in NMP?less than 608 mg/L of carbazole in NMP?.By using this modified MWNTs,the tensile strength and flexural strength of MWNTs/PEEK composites can be improved to 14.5%and 116.7%,when the weight percent of MWNTs is only 2%in this composite,at the same time,better toughening effect is also exhibited.In fact,dispersed and coated MWNTs without solvent is the most suitable way for the practical application.And modified MWNTs without solvent also can further simplify the preparation technology and adapt to the production condition,the in-situ polymerization and blending strategy was studied.In detail,naphthalene monomers were absorbed on the MWNTs surfaces firstly,the with degree of polymerization increased,the naphthalene based PAEK copolymers realized the coating for MWNTs surfaces,and then these modified MWNTs were dispersed well by mechanical agitation.By this method,an naphthalene based PAEK copolymer with MWNTs was synthesized successfully,and MWNTs also can be monodispersed well in the copolymer matrix.For further improve the mechanical property,carbon fiber was introduced into this naphthalene based PAEK copolymer with MWNTs by melt blending.Due to the micro-nano synergy,the mechanical property of this composite was improved observably.