ARAMIDE BLOCK COPOLYMER AND METHOD OF PREPARATION THEREOF Russian patent published in 1999 - IPC

FIELD: polymerization processes. SUBSTANCE: new aramide block copolymer is prepared from aromatic diamines and contains at least two I type aramide blocks and at least two II type aramide blocks such that blocks of the two types are flexible in solution and in solid non-stretched state, and (i) I type aramide block is regarded as rigid after stretching if, after stretching, aramide homopolymer with sufficient molecular weight has initial coefficient of elasticity higher than 250 g/denier, and (ii) II type aramide block is flexible after stretching if, after stretching, aramide homopolymer with sufficient molecular weight has initial coefficient of elasticity 200 g/denier or lower. I type aramide block basically contains 0-15-50 mol % (I), 0-35 mol % (II), and 50 mol % (III) (formulas in description) where Z¹ is NH and Z² CO or vice versa; Y₁ is O, S, SO₂, or CO; n=0 or 1; when n=0, X¹ is hydrogen and X² chlorine or methyl; when n=1, X¹ and X⁴ are hydrogen atoms and X² and X³ are chlorine, bromine, methyl, nitro, trifluoromethyl, carboxyl, and COOR (R is lower alkyl), or X² and X³ are hydrogen atoms and X_i and X₄ are chlorine, methyl or methoxy; when Z² is NH, Ar is p-phenylene optionally substituted by chlorine or methyl; when Z² is CO, Ar is the same and, additionally, 2,6-naphtylene and II type aramide block is built from residues of isophthalic acid and m-phenylenediamine, isophthalic acid and 4,4'-oxydianiline, and 4,4'-oxydibenzoic acid and m- phenylenediamine, number of repeated units in each of indicated first aramide blocks and indicated second aramide blocks being at least 3. EFFECT: increased strength of stretched fibers with high modulus. 18 cl, 11 tbl, 7 ex