The direct polymerization method regulates the relative molecular weight and distribution of PP through polymerization process and catalyst, accelerates the chain transfer reaction through hydrogenation and other means, reduces the relative molecular weight of the polymer, and increases the melt flow rate (MFR) of PP raw materials(KN95 Meltblown Company). .

At present, there are many related researches on controllable degradation methods, but there are few researches on the structure and properties of ultra-high melt flow PP produced by direct polymerization method. Next, the relative molecular mass distribution characteristics and melt crystallization properties of the ultra-high melt flow PP produced by the direct polymerization method are studied, and the influence of its structure on the spinning process is also discussed.

a) The relative molecular mass distribution of ultra-high flow PP produced by direct polymerization method is wider than that produced by chemical degradation method, and when the MFR is similar, its number average relative molecular mass is much lower than that of PP produced by chemical degradation method.

b) The PP sample produced by the direct polymerization method has a lower melting temperature, and the crystallinity and crystallization temperature are higher than that of the PP produced by the chemical degradation method, and the crystallization performance is better, which needs to be considered in the spinning process.

c) The direct polymerization method of PP raw materials has a certain influence on the preparation process of the meltblown nonwoven fabric. The fiber cools and sets faster, and the meltblown nonwoven fabric(Meltblown Factory) has high stiffness and strength, but the fiber diameter is relatively thick.