Method for concentrating polymer solution in a planetary screw extruder and manufacturing thermally crosslinked polymer simultaneously mixing with a modified liquid comprising a filling zone operating in the atmosphere and the degassing and cooling zone operating under vacuum

Provided herein is a method for concentrating polymer solution in a planetary screw extruder and manufacturing thermally crosslinked polymer simultaneously mixing with a modified liquid, which is characterized in that: (a) the planetary screw extruder comprises a filling zone operating in the atmosphere and the degassing and cooling zones operating under vacuum at the downstream, the filling zone is formed by at least one screw barrel, wherein the length of the filling zone operating under the atmosphere is not more than one-half of the total length of the planetary screw extruder, preferably no more than one-third; (b) the degassing and cooling zone of the planetary screw extruder operating under vacuum consists of at least four, preferably exactly four, screw barrels connected to each other, they each have a vacuum port on the sleeve, the vacuum ports having a cross section of at least 5% of the area of the sleeve that is passed by the planet screw, and the vacuum system is applied through the vacuum ports;