Biodegradable High-Molecular-Weight Poly(pentylene adipate-co-terephthalate): Synthesis, Thermo-Mechanical Properties, Microstructures, and Biodegradation

Poly(pentylene adipate-co-terephthalate) (PPAT) is a promising biobased and biodegradable polymer that can replace polyethylene in flexible packaging films where biodegradability is desired. High-molecular-weight (100K–145 KDa) aliphatic–aromatic polyester PPAT was successfully synthesized, and the effects of reaction conditions on molecular weight were reported. PPAT polyesters were characterized for polymer compositions, number-average unit length, thermal transitions, and rheological properties. PPAT compression-molded films were characterized for crystallinity and tensile properties to correlate micro- and macroproperties. PPAT compression-molded films exhibited up to a 76% higher tensile modulus than compression-molded films from poly(butylene adipate-co-terephthalate) (PBAT), making PPAT films potentially comparable with compression-molded films from linear low-density polyethylene (LLDPE). PPAT is biodegradable in soil and freshwater environments with estimated 90% biodegradation times of 504–580 and 604–845 days, respectively, while PBAT takes 971 days in soil and 395 days in freshwater.