Compatibilized blends of biodegradable polymers with improved rheology

A polymer blend comprising:

• (A) about 5% to about 95% by weight of at least one polymer (A) having a glass transition temperature less than about 0° C., wherein said polymer (A) is an aliphatic-aromatic copolyester comprising:
• (1) diacid residues comprising about 1 to 65 mole percent aromatic dicarboxylic acid residues;
• and 99 to about 35 mole percent of non-aromatic dicarboxylic acid residues selected from the group consisting of aliphatic dicarboxylic acids residues containing from about 4 to 14 carbon atoms and cycloaliphatic dicarboxylic acids residues containing from about 5 to 15 carbon atoms;
• wherein the total mole percent of diacid residues is equal to 100 mole percent;
• and
• (2) diol residues selected from the group consisting of one or more aliphatic diols containing about 2 to 8 carbon atoms, polyalkylene ethers containing about 2 to 8 carbon atoms, and cycloaliphatic diols containing from about 4 to 12 carbon atoms;
• wherein the total mole percent of diol residues is equal to 100 mole percent;
• (B) about 5% to about 95% by weight of at least one polymer (B) having a glass transition temperature greater than about 10° C., wherein said polymer (B) is a biopolymer based on polylactic acid;
• and
• (C) about 0.25 to about 10 weight % of at least one compatibilizer (C), said percentages being based on the total weight of the polymer blend;
• wherein the polymer blend has a higher zero shear melt viscosity than polymers (A) and (B) separately;
• wherein said compatibilizer (C) comprises a polyacrylate.

A polymer blend comprising:

• (A) about 5% to about 95% by weight of at least polymer (A), wherein said polymer (A) is an aliphatic-aromatic copolyester consisting essentially of:
• (1) aromatic dicarboxylic acid residues comprising about 35 to 65 mole percent of terephthalic acid residues and 65 to about 35 mole percent of adipic acid residues, glutaric acid residues, or combinations of adipic acid residues and glutaric acid residues;
• and
• (2) diol resklues consisting of 1,4-butanediol;
• (B) about 5% to about 95% by weight of at least one polymer (B), wherein said polymer (B) is a biopolymer based on polylactic acid;
• and
• (C) about 0.25 to about 10 weight % of at least one compatibilizer (C) consisting essentially of polyacrylate, said percentages being based on the total weight of said polymer blend;
• wherein said polymer blend has a higher zero shear melt viscosity than polymers (A) and (B) separately.