Ziegler-Natta Catalysts Preparation And The Performance For Olefins Polymerization

Internal electron donor plays an important role in catalytic performance of MgCl₂-supported Ziegler-Natta catalyst in olefin polymerization.It still is a key issue to prepare the new and good internal electron donor in the development of novel Ziegler-Natta catalyst.In this dissertation,a series of internal electronic donors containg norbornylene ring were synthesized and applied in preparing MgCl₂-supported Ziegler-Natta,the catalytic performance were estimated in 1-butene and propylene polymerization.Furthermore,poly?1-butene?was modified by filling with 5-norbornene-2,3-dicarboxylic acid salt,where the effect of nucleating agents and its content on mechanical properties and crystalline properties were studied.The main research contents are as follows:?1?5-Norbornene-2,3-dicarboxylic acid diethyl ester?NDDE?with different geometric configuration?endo,exo and trans?were synthesized and employed as IED in MgCl₂-supported Ziegler-Natta catalyst for the 1-butene and propylene polymerization.It was found that the configuration of IED has negligible effect on the propylene polymerization,while it plays markedly roles in tuning the catalytic activity for 1-butene,molecular weight?Mw?and polydispersity index?PDI?of resulting PB.Under the optimal conditions,the Cat-1containing endo-NDDE shows the highest catalyst activity up to 27.3 Kg PB/g?Ti,while the Cat-2 with exo-NDDE has the lowest catalyst activity of 16.3 Kg PB/g?Ti.The PB obtained by Cat-3 containing trans-NDDE possess the largest Mw?15.4×10⁵ g/mol?and the widest PDI?PDI=10.8?,which is 1.4 times of PB achieved from Cat-1.The deconvolution of the gel permeation chromatography?GPC?curve into individual Flory distribution curves by Schulz-Flory method was applied in investigating the influence of configuration on active center.The result demonstrated that the active sites distribution are tunable by employing different stereostructure of IED,however,the number of active center keep constant with the varying stereostructure of IED.The coordination of IED to MgCl2 and TiCl4 were investigated by IR spectroscopy,it was found that only one C=O group of trans-NDE?IED-3?coordinate to MgCl2 in the catalyst,differing from the endo-NDE and exo-NDE.?2?5-Norbornene-2,3-dimethyl carboxylates?NBDMC?and bicyclo[2.2.1]hept-2,3-dicarboxylic acid diethyl esters had been synthesized and applied as IEDs in Ziegler-Natta catalysts,where it was found that chemical structure and steric effect of substituent of these IEDs has an remarkable effect on the 1-butene polymerization.The performances of the NBDMC-based Ziegler-Natta catalysts are inferior to Ziegler-Natta catalysts bearing NDDE as IED.What is more,the Mw and PDI of resulting PB catalyzed by Cat-A were also decreased.?3?A series of nucleating agent of 5-norbornene-2,3-dicarboxylic acid salts were synthesized and the influence of nucleating agents on the mechanical properties and crystalline properties were investigated.The results revealed that the mechanical properties of PB has a slightly dependence on the 5-norbornene-2,3-dicarboxylic acid salts.However,the salts are beneficial for enhancing crystallization in form?and accelerating the transformation from form?to form?,especially for endo-ND-Zn and endo-ND-La as nucleating agents.?4?The effect of proportion of endo-ND-Zn and ZnO in the mixture of endo-ND-Zn and ZnO?endo-ND-Zn/ZnO?on the crystalline behavior of PB was investigated by fourier transform infrared spectrometer?IR?,polarizing optical microscope?POM?and differential scanning calorimetry?DSC?.The results showed that component of endo-ND-Zn benefits the promotion of transformation from form?to form?and the improvement of the proportion of crystal form?,while ZnO in the mixture is beneficial for forming perfect crystal.The crystallization active energy?-?E?of PB were calculated by Kissinger method.It was found that the-?E is dramatically declined from 185.48 kJ/mol to 141.97 kJ/mol when the percentage of the ZnO in the mixture of endo-ND-Zn/ZnO was more than 50%,indicating that ZnO was favorable for nucleation crystallization.?5?The crystallization characteristics of poly?butene-co-propylene?were investigated by POM method.The results showed that the incorporation of the PP component into PB is effective to improve the crystallizing rate and decrease the spherulite size of PB.