Biodegradation behavior and material properties of aliphatic/aromatic polyesters of commercial importance

Copolyesters of aliphatic monomers with a defined amount of terephthalic acid recently have been shown to be biodegradable. This group of plastic materials exhibits very interesting material properties with regard to their technical application potential. A tensile strength of 25 N/mm(2) combined with elongations at break up to 1500% was achieved for BTA materials. Melting points varied from 80 to 140 degrees C. Biodegradation rate under compositing conditions were determined, showing typical erosion rates of films, in the range of 5 to 10 mu m/week. The material properties and the degradation rate as well can be adjusted by the copolymer composition. Stretching of the polymer in the cold state leads to 10-fold higher mechanical strength of the material. The polyester chain can be extended to high molar masses, resulting in melt viscosities suitable, e.g., for melt below extrusion.