Studies On Crystallization Behaviours And Tribological Properties Of Polyazomethines/Nylon 6 Composites

In this dissertation, two kinds of polyazomethines(PAM)/nylon 6 in situ polymerization composites with different rigidity of PAM are synthesized through anionic polymerization. The crystalline forms and melting behavior are characterized by WAXD, FT-IR and DSC. The results show that a is still the main crystalline form of composites.DSC has also been used to study the isothermal and nonisothermal crystallization kinetics. The linear simulations indicate that the primary stage of both isothermal and nonisothermal processes can be described by Avrami equation, however the linear relations deviate due to the secondary crystallization, particularly for that of nonisothermal crystallization.In the isothermal crystallization experiment, the DSC exothermic curves become flat as decrease of the degrees of undercooling within the experimental temperatures. For more rigid PAM1/nylon 6 composites, the rates of crystallization monotonously increase with the contents of PAM1; while for PAM2/nylon 6 composites, the rates of crystallization attain the maximum when the contents of PAM2 are 5 wt%. This may suggests that the crystallization of matrix is induced by micro fibrils of PAM and that the more rigid of microfibrils of PAM the more effects of induction. The results of linear regression indicate that the addition of PAM do not alter the avrami exponents, about 2-3, which suggests that the crystallization modes might be a mixture of three-dimensional spherulite and two-dimensional circular. For PAM 1/nylon 6 with more rigidity composites, the rates of crystallization.During nonisothermal crystallization, the DSC crystallization curves and crystallization temperature Tp move towards lower temperature. At the same cooling rate, the crystallization rates of PAM 1/nylon 6 increase with the contents of PAM1; while the crystallization rates of PAM2/nylon 6 attain maximum with 5% contents of PAM2. This results agree with that ofisothermal crystallization kinetics.The tribological properties are investigated by M-200 wear machine. In the dry sliding experiments of composites, friction coefficients decrease with the loads. Plastic deformation happens in the worn surface where the element of Fe is found, so PAM microfibrils support part of the load and prevent the further deformation. On the condition of high speed and high load, the worn surface of PAM 1/nylon 6 composites nearly melt and comparatively uniform transfer on the surface of steel is formed, which accounts for the rather low wear mass loss. The infrared analysis show that the a small quantity of transition of crystal form from a into y of nylon and its composites happen during dry friction because of the high temperature and strong sheering strength. The effects of heat treatment on dry friction and tribological properties under water lubricating are also studied elementarily.