What are the factors affecting the isotacticity of polypropylene?
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As the title suggests, factors that generally affect the isotacticity of polypropylene include the moisture content in propylene, quality issues with the catalyst itself, and insufficient amounts of silane added. From a production perspective, which control parameters or processes can influence the isotacticity of polypropylene?
In the production process of polypropylene (PP), the isotactic index is one of the important quality control parameters, as it reflects the degree of crystallization of PP molecules. When the monomers are arranged in a stereoregular order, PP has a high degree of crystallinity, that is, a high isotactic index. PP products with a high isotactic index exhibit high tensile strength, high surface strength, and good heat resistance, whereas their impact strength is reduced
Too low an amount of electron donor will result in low isotacticity of the polymer and the formation of random structures; what is the effect of using too high an amount? ? ?
An excessive amount of electron donor can make polypropylene brittle and prone to producing fine powder, which has a slight impact on heat exchangers, bag filters, etc.
I also believe that the reactor residence time is short (overloaded), and the reaction temperature control is poor, which leads to the formation of oligomers and thus affects the regularity of the polypropylene
Low control of temperature and pressure during polypropylene production can lead to the formation of oligomers. The residence time in the reactor affects the degree of isotacticity, which is not easy to understand
What is the impact on heat exchangers and bag filters?
A large amount of polypropylene powder can easily clog the bag filters, reducing the service life of these filters. In batch reactors, the amount of polypropylene powder carried in the circulating gas increases, which can lead to accumulation and blockage in the heat exchangers. Of course, this is also related to the reaction load and the desired product grade; this problem does not occur in continuous flow reactors