METHOD FOR MANUFACTURING A POLYMER COMPOSITION AND POLYMER COMPOSITION

PROBLEM TO BE SOLVED: To provide a polymer composition exhibiting enhanced strengths, above all tensile strength, by virtue of the enhancement of the dispersibility therein of a fiber component and a method for manufacturing the same polymer composition.SOLUTION: The provided method for manufacturing a polymer composition includes a step of forming a polymer component by polymerizing at least one type selected from the group consisting of conjugated diene compounds and non-conjugated olefins in the presence of a polymerization catalyst composition obtained by using a first element comprising a rare earth element compound or a rare earth metal element-containing compound including a reaction product of the rare earth element compound and a Lewis base, a second element including a compound expressed by the following general formula (X), and a third element including a hydrophilic fiber, specifically by adding and reacting the first element to and with an admixture provided by mixing and aging the second element and the third element: YRRR(X) (where Y is a metal selected from the group consisting of Group 1, Group 2, Group 12, and Group 13 metals of the periodic table; Rand Rare either hydrocarbon groups having 1-10 carbon atoms or hydrogen atoms; Ris a hydrocarbon group having 1-10 carbon atoms; Rand Rmay be mutually identical or different; in a case where Y is a metal selected from among Group 1 metals of the periodic table, a is 1 while b and c are 0; in a case where Y is a metal selected from among Group 2 and group 12 metals of the periodic table, a and b are 1 while c is 0; in a case where Y is a metal selected from among Group 13 metals of the periodic table, a, b, and c are 1).