| Impact polypropylene copolymer(IPC)is widely used in automotive interior and exterior decoration.municipal industrial pipe,home appliance shell and other-fields due to its excellent impact resistance.However,in some special occasions such as low temperature and cold environment,the impact performance of IPC is still not satisfactory.So,the improvement of toughness is necessary.(3-PP has been given a lot of attention because of its outstanding toughness.At present,the access to high content of ?-PP in industrial is to add ?-nucleating agent(?-NA).Nowadays,most of the nucleating agents is dissolved or not melting in pp,mainly exists in the form of particles,so the traditional method of adding nucleating agent is difficult to avoid the agglomeration,also hard to achieve more uniform dispersion,which reduces the efficiency of its nuclear.To improve the efficiency of the nucleation of nucleating agent,avoid the agglomeration and achieve more uniform dispersion,this article introduced the thought of "in situ preparation",?-nucleation agent(Adi-Zn)is synthesized in situ during the extrusion process.The nucleation properties of Adi-Zn in IPC were studied.First,Adi-Zn was synthesized using three synthetic methods to study its nucleation effect on impact polypropylene copolymer.When the Adi-Zn concentration is 0.1%,the impact strength of nucleated IPC is 1.63 and 2.03 times than that of neat IPC respectively,and the crystallization temperature is 12.3 ? higher than that of neat IPC,the kp value is 0.95.It was found that nucleated polypropylene appeared bright ?-PP and the spherulite size was greatly reduced by means of POM.The result of non-isothermal crystallization kinetics study indicates that kinetics of IPC is well described and the crystallization rate of nucleated IPC is faster than that of neat IPC.Then,by means of multiple testing methods,we confirmed that zinc adipate produced during extrusion act as ?-NA.Adi-Zn formed by the reaction is further sufficiently dispersed in the IPC matrix by shear mixing of the twin-screw to achieve good dispersibility.The primary reasons for the excellent Adi-Zn nucleation performance are in-situ synthesis and good dispersibility in IPC.Next,the effects of injection molding conditions and annealing treatment on the mechanical properties of IPC were studied.The most suitable melt temperature was found to be 200 ?.The mold temperature has little effect on the rigidity and toughness of IPC.The higher the annealing temperature and the longer the annealing time,the better the mechanical properties.Finally,Flash DSC was used to study the effect of cooling rate on the crystallization behavior of IPC.For the nucleated IPC,the faster the cooling rate,the more significant the inhibition effect on the growth inhibition of ?-PP.The exponential equation y=Ae-x/t"+y0 is derived to predict the crystal peak temperature of IPC at different cooling rates.The phenomenon of double crystal peaks in the crystallization process is explained,and the appearing of the second crystal peak is due to the nucleation formation of the ethylene chain segment. |
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