Polypropylene Molecular Structure Of The Process Of Industrialization

Polypropylene is a kind of polymers with excellent property. The consumption of polypropylene increases continually as a result of the technology advances. Especially, in the last two decades, polypropylene grows in fast speed. The development and the advancement of propylene techniques and catalysts are the important reasons to promote the progress of propylene.Mass polymerization and gas-phase polymerization are dominating techniques in internal propylene techniques. Different techniques bring impact polypropylene copolymers (IPC) with similar melting flow rate (MFR), however, different properties, which is the result of the differences in the chemical microstructures of the products. In this thesis, the compositional differences of impact polypropylene and polyethylene copolymers industrially manufactured by the following two methods are investigated. The results showed that the content of the rubber in PP-b-PE manufactured by mass polymerization was less than that by degradation. The degree of crystallinity of chloroform-insoluble fraction of the PP-b-PE manufactured by mass polymerization is higher than that of by degradation. Moreover, the compositional difference of impact polypropylene and polyethylene copolymer manufactured industrially by gas-phase polymerization with different melting flow rate was also studied.Thanks to the development of the catalysts, polypropylene techniques have made great progress. With the improvement of the reactivity, selectivity and shape of catalysts, the propylene techniques have been improved greatly and the cost reduced.The recent progress of Zegler-Natta(Z-N) catalyst is the broaden production range of Z-N catalyst and the different donors systems. Different kinds of external donors affect the crystallization and stereoregularity of the obtained polypropylene. In the present work, 9 samples produced industrially by 5 kinds of external donors were characterized by ¹³C nuclear magnetic resonance (NMR) and Gel permeation chromatography (GPC) spectroscopy, as well as differential scanning calorimetry (DSC) and thermal fractionation. The results of NMR showed that stereoregularity was interrelated external donor's cubage.