Abstract: The invention relates to a field of polymer preparation and discloses a method for promoting phase-separation of polymer solution. The phase-separation method of polymer solution of the invention comprises: at least a portion of the polymer solution is subjected to a heat treatment under flowing so that the polymer solution is divided into a clear liquid phase and a concentrated liquid phase, wherein the Reynolds number of the polymer solution flowing is 0.2-30. By performing the heat treatment under specific Reynolds number conditions, the invention permits to reduce the temperature of phase-separation of solution, reduce the time of phase-separation of solution, and significantly reduce the material consumption and energy consumption of the entire process, compared with the existing technology that only performs phase-separation through heat treatment.

Abstract: The invention belongs to the field of olefin polymerization and relates to a propylene-based copolymer, its preparation process and use, and a polypropylene composition thereof. The propylene-based copolymer can contain 60-95 wt % of propylene-derived structural units and 5-40 wt % of comonomer-derived structural units; the propylene-based copolymer has a comonomer dispersion degree D[PCP]/[C] in the range of 50%-70%, wherein the comonomer dispersion degree D[PCP]/[C]=[PCP]/[C]×100%. Upon blending the propylene-based copolymer of the present invention with a polypropylene, the copolymer has excellent compatibility with polypropylene, and can promote the crystallization of the polypropylene and can improve the mechanical properties of the resulting polypropylene material.

Abstract: Disclosed is a biphenol metal complex. The structure thereof is as represented by formula I, wherein R1 and R1? are each independently selected from hydrogen and a substituted or unsubstituted C1-C20 hydrocarbyl; R3—R7, R3?—R7? are each independently selected from hydrogen and a substituted or unsubstituted C1-C20 hydrocarbyl, any two adjacent groups of R3—R7 are optionally linked to form a ring, and any two adjacent groups of R3?—R7? are also optionally linked to form a ring; M and M? are each independently selected from the Group 4 metals; each X is independently selected from the group consisting of a hydrocarbyl having 1 to 20 carbon atoms, hydride, amido, alkoxide, alkyl sulfide, alkyl phophide, halide, diene, amine, phosphine, ether, and combinations thereof; m and n are independently an integer of from 1 to 4; and L is a divalent linking group.

Abstract: Disclosed is a catalyst for olefin polymerization, comprising a main catalyst and a cocatalyst; the main catalyst is a bisphenol metal complex represented by formula I, and the cocatalyst comprises an organoaluminum compound; in formula I, R1, R1?, R2, R2? are the same or different, and are each independently selected from hydrogen and a substituted or unsubstituted C1-C20 hydrocarbyl; R3-R7, R3?-R7? are the same or different, and are each independently selected from hydrogen and a substituted or unsubstituted C1-C20 hydrocarbyl; R8 and R9 are the same or different, and are each independently selected from hydrogen or a substituted or unsubstituted C1-C20 hydrocarbyl; M and M? are the same or different, and are selected from Group IV metals; and X is halogen;