Synthesis And Tribological Properties Of Fluorine Containing Special Engineering Plastics Poly(ether Sulfone)

Polymer materials have been widely used in the field of friction because of their many advantages such as flexible molecular structures,the changing of the modification,the processability and self-lubricating property.Special engineering plastics are one of them which show best comprehensive thermal stability,excellent mechanical properties,creep resistance,corrosion resistance and frictional wear properties,and have important applications in the machinery,electronics,aerospace,automotive,food and medical treatment and other national economy fields.However,with the development of material science and the need of diversified applications,the research on the functional modification of special engineering plastics has become extremely important and urgent.As a kind of resin based friction material,PES shows high coefficient of friction and wear rate under the dry sliding friction condition.Therefore,PES tribological modification has become a hot research topic in recent years.The PES materials modified by blending with fluorine resin have been widely used as self-lubricating mechanical parts and nonstick coating.But interfacial compatibility of composites may also cause defect of other basic property,such as mechanical and thermal properties.Chemical modification of PES is one of the best ways to solve these problems.In recent years,there are few reports on the modification of PES special engineering plastics by using of perfluorinated groups.The tribology research is the most prominent feature of the surface problem,and it means perfluorocarbon groups have obvious influence on Tribological Properties.On the propose of without changing the basic properties of polymer,and improving the properties of PES materials with low content of perfluorocarbon groups,end group synthesis way was chosen.And in order to investigate the tribological properties of high fluorine content of modifiedPES,we design a branched modification way to compare with end-capping way.In this paper,based on the background of PES,PEEK and other series of special engineering plastics research in our center,two types of PES special engineering plastics modified by different perfluoroisopropyl groups,were in-depth studied with fluoride content,molecular structure and external factors research on tribological property.Firstly,perfluoroalkyl terminated and perfluorinated branched PES(PES-F and PES'-F)were prepared.The PES-F and PES'-F with different fluorine content were obtained by adjusting the ratio of the molecular weight and nucleophilic condensation polymerization.End group modification had little influence on the thermal stability and mechanical properties,and although tensile strength,modulus,elongation and thermal stability of PES'-F decreased with high fluorine content,PES'-F with low copolymerization ratio still showed good thermal and mechanical properties.By contact angle measuring,influence of the effect of heat treatment on fluorine migration of the two modified polymer was studied.The results showed that the heat treatment promoted the trend of fluorine migration,until it reached stable on the material surface.By heat treatment,the surface energy of the two kinds of materials can be reduced to 16.3 mJ/m2 and 14.1 mJ/m2,which even lower than that of polytetrafluoroethylene(18.5mJ/m2),and the surface energy of PES had be reduced greatly.The tribological properties of PES,PES-F and PES'-F were studied systematically.The results showed that the introduction of perfluorinated group can reduce the friction coefficient and wear rate.In the running stage of friction tests,the dynamic change of the material surface fluorine content on the friction coefficient and wear rate was quite obvious,while as the fluorin was grind off,the florine content on the surface were the same with that in ontology.It showed that the friction property of modified PES was directly related to the fluorine content.The tribological properties of the two kinds of materials were compared with the changes of fluorine content,external conditions and friction and wear mechanisms.The result showed that friction coefficient and wear rate of the material can be affected by the fluorine content and the molecular structure.And the self lubrication performance of PES-F was better than that of PES'-F,which were under the same level of fluorine content,and it showed the superiority of end group modification.Perfluorocarbon modified PES has the application prospect in the field of special engineering plastics tribology.This paper provided the theoretical guidance which dealing with the study on special engineering plastics modification research.