| At present,the scale of automobiles in our country is huge,and automobiles are gradually moving towards lightweight and comfort.Polypropylene is an indispensable material for automobiles,which is becoming more and more popular in the automotive industry.Polypropylene with high fluidity and high rigidity has the advantages of high melt flow rate,high flexural modulus,low energy consumption,good processing performance and so on.It is widely used in automotive interior parts,door linings and other large-scale parts.Based on the current situation,this paper has conducted a study on polypropylene with high fluidity and high rigidity,and carried out the development of high-flow and high-rigidity copolymerized polypropylene products on the polymerization devices of different scales.This project aims at preparing high-flow and high-rigidity copolymerized polypropylene,not only uses catalysts to conduct mold test and pilot-scale polymerization process research,but also studies and improves the structure as well as performance of the prepared co-polypropylene.The details are as follows:(1)Using catalysts A and catalyst B as the main catalysts to study the effects of hydrogen addition amount on catalyst activity,polypropylene isotacticity and melt flow rate,and compare the performances of the corresponding polymers towards the two catalysts.By selecting the high-performance catalyst B,the problems of fine particle size and low isotacticity of polypropylene powder during the production process were solved.On a 75 kg/h Spheripol ? polypropylene pilot plant in Lanzhou Chemical Research Center,the loop flow reactor was used to adjust the amount of hydrogen which was added to change the polymer melt flow rate,thereby improving the polymer melt flowability.Through adjusting and optimizing the production process parameters,the high-flow and high rigidity impact copolymerized polypropylene EP508 N were successfully prepared.(2)Taking polypropylene EP508 N prepared on the pilot plant of Lanzhou Chemical Research Center as the research object,which was graded by o-xylene to study its composition and ethylene content,and their effects on materials properties.The composition and morphology of impact copolymerized polypropylene were analyzed by TREF,GPC,DSC,FTIR,SEM,POM and other methods,and the processing properties of the impact copolymerized polypropylene were studied by capillary rheology.At the same time,the structure and performance of EP508 N and imported similar products BX3900 were compared.The results showed that the distribution of rubber phase,molecular weight and its distribution,as well as composition distribution towards EP508 N are reasonable,the material not only possessed excellent fluidity(melt flow rate of 60.4 g/10 min),rigidity(flexural modulus of 1300 MPa),but also had good balance of rigidity and toughness,and its comprehensive performance reached the level of similar imported products.(3)In order to further improve the overall performance of EP508 N,the effects of different nucleating agents and their addition amounts on the polymer properties were studied.The influence of nucleating agent on the crystallization temperature and spherulite size towards polypropylene was analyzed by POM and DSC.In addition,the influence of nucleating agent addition amounts on the mechanical properties and thermal deformation temperature towards the material was investigated to determine the optimal addition ratio.These results showed that the comprehensive performance of the product when adding the nucleating agent EPX-715 is better than the nucleating agent NAA-325,and the performance is the best when the addition ratio is 0.07 %. |
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