POLYACRYLONETRILE (PAN) POLYMERS WITH LOW INDEX OF POLYDISPERSITY (IPD) AND CARBON FIBERS RECEIVED FROM THEM Russian patent published in 2018 - IPC C08F2/06 C08F2/38 C08F220/44 C08F6/00 D01D5/06 D01F9/22 

FIELD: chemistry.

SUBSTANCE: invention relates to a method for the preparation of a polyacrylonitrile (PAN) polymer with a narrow molecular weight distribution and to a method for producing a carbon fiber from a PAN-polymer. Method for producing a polyacrylonitrile polymer is, acrylonitrile monomer is combined with the solvent with at least one comonomer and a thiocarbonylthio compound. Derived solution is heated to a temperature of 40 °C to 85 °C. Then, an initiator is added to the solution to control the polymerization reaction. Polymerization is regulated by a controlled / live radical polymerization in which the thiocarbonylthio compound acts as a reversible-attachment-fragmentation transfer agent (RAFT). Comonomer is selected from the group consisting of vinyl acids, vinyl esters and vinyl derivatives. Initiator is an azo compound or organic peroxide. Method for producing a carbon fiber is that the solution of the above mentioned polymer is first obtained. Then, wet-molding or air-gap molding is performed, forming a polyacrylonitrile fiber precursor, which is coagulated in a coagulation bath. Further, the fiber precursor is pulled from the coagulation bath by rollers through a wash bath to remove the coagulant excess. Fiber precursor is then stretched in hot water baths to impart molecular orientation to the fibers. After this, the elongated precursors of the fibers are dried. Fiber precursor is then oxidized alive in one or more furnaces to which heated air is supplied. Next, the oxidized precursor of the fiber is carbonized in one or more furnaces having inert, oxygen-free atmosphere.

EFFECT: invention provides a polyacrylonitrile polymer that has a low polydispersity index of 2 or less, and a molecular weight in the range of 60 kg/mol to 500 kg/mol, and produces carbon fibers with improved mechanical properties, a constant cross-section and small microdefects.

13 cl, 3 dwg, 2 ex, 8 tbl