Anionic Grafting Of Nylon 6 Onto Kevlar Fiber And Its Effect On The Structure And Capability Of Composites

Composites are constitued of various components which have different properties. It's synthesize function is more superior than the component.But in some high technology fields,especial in aerospace industry,Kevlar fiber(KF) is widely applied for its high strength and modulus,and special shows important function in aerospace and other construction material fields. However,the interface between fiber and matrix is the weak area in composites which are reinforced by fiber,therefore the improvement of interfacial adhesion,the hotspot in composites research,is of great significance.To deal with the aforementioned problems,the research plans of this thesis are as follows: 1.On the basis of the literature review,the general situation of composites at home and abroad,the structure ,function ,application and development of KF were summarized.At the same time a review was made systematically in the methods of KF surfacial modification,and the meaning of research the structure and capability of composites strengthened by KF was expatiated. 2.Chemical disposal was used to treat the surface of KF,and activity groups were induced onto the surface of KF by hydrolyzation;after that KF was treated by adipyl choloride and stabilized by carprolactam;Finally,the anionic grafting of nylon 6 onto the the surface of KF was proceeded,and the effect of react temperature and time were also discussed.FT-IR,XPS and ESEM were used to study the appearance and chemical components of the KF which was grafted and ungrafted by nylon 6.The results showed that the grafted polymer on the surface of KF is greatly similar to matrix,and the anionic grafting of nylon 6 onto KF surface could be available. 3.The KF which treated and untreated were used to make reinforcing nylon6/Kevlar fiber (PA6/KF) composites.Particular attention was paid to the effect of surface treatment on the crystalline and melting behaviour of PA6/KF composites.The analysis of DSC showed that the isothermal crystallization of PA6 was dominated by nucleation while the KF played a role of heterogeneous nucleation agent in the process of crystallization of PA6 and increased its crystalline rate;KF has improved the initial crystalline temperature (Tconset) of PA6 while reduced its total crystalline time (ttotal) during the nonisothermal crystalline process;the induction of KF also could influence the melting behavior of PA6. 4.PLM was carried out to observe the interfacial crystalline effect of PA6/KF composites.The results showed that the ungrafted KF and grafted KF can both induce transcrystallization in PA6/KF composites in the range of the beginning crystallization temperature and approaching melting temperature.The transcrystallization was more fine and perfect at higher crystallization temperature than at lower crystallization temperature,so was the ability of inducing transcrystallization.The grafted KF enhanced the growth ability of transcrystallization and promoted PA6 to form more fine and perfect transcrystallization than the ungrafted KF atrelative lower crystallization temperature. 5.The effect on mechanical properties and fracture morphologies of PA6/KF composites by anionic grafting nylon 6 onto KF was studied.It showed that the composites which were reinforced by untreated KF would destroy from the interface, while the composites which were reinforced by treated KF would destroy from other place partly, which contributed to improving the tensile strength, flexural strength and flexural modulus,however,the impact strength declined.