Abstract: A deep-dyeable modified polylactic acid fiber includes a modified polylactic acid composition containing polylactic acid and a modifying polymer. The modifying polymer is an aliphatic polyester other than polylactic acid, an aromatic polyester, an aliphatic-aromatic copolyester, or combinations thereof. The modified polylactic acid composition, when dyed, provides a decreased L-value compared to a non-modified polylactic acid composition that is dyed under the same dyeing conditions as the modified polylactic acid composition and that contains the polylactic acid but is free of the modifying polymer.

Abstract: A method for preparing a biodegradable copolyester includes: (a) optionally preparing an aromatic prepolymer by reacting a first aromatic dicarboxylic compound with a first aliphatic glycol; (b) reacting the aromatic prepolymer with a second aromatic dicarboxylic compound and a second aliphatic glycol so as to form a first reaction product; (c) reacting the first reaction product with an aliphatic dicarboxylic compound so as to form a second reaction product; and (d) performing polycondensation of the second reaction product.

Abstract: A method for preparing a biodegradable copolyester includes: (a) optionally preparing an aromatic prepolymer by reacting a first aromatic dicarboxylic compound with a first aliphatic glycol; (b) reacting the aromatic prepolymer with a second aromatic dicarboxylic compound and a second aliphatic glycol so as to form a first reaction product; (c) reacting the first reaction product with an aliphatic dicarboxylic compound so as to form a second reaction product; and (d) performing polycondensation of the second reaction product.