Effect of chain extender and light stabilizer on the weathering resistance of PBAT/PLA blend films prepared by extrusion blowing

Biodegradable poly (butylene adipate‑co‑terephthalate)/polylactic acid (PBAT/PLA) films were prepared by melt blending and blowing technology under the presence of a chain extender and two different light stabilizers. A comparison of the infrared spectra of the film with and without these additives before and after the weathering tests showed that the addition of chain extender and light stabilizer improved the polymer weathering resistance significantly. Without PLA, PBAT underwent serious chain scissions and crosslinking during the weathering. PBAT/PLA film chain scissions were weakened as the PLA content increased. After 200 h of the weathering, the machine direction (MD) tensile strength as well as MD and transverse direction (TD) elongation at break of both PBAT and PBAT/PLA films decreased, while their TD tensile strength changed only slightly. The film with the 85:15 PBAT:PLA ratio containing 1.5 phr of chain extender showed much better flexibility without any changes to its tensile strength. The addition of 0.6 phr of light stabilizer (Chimassorb2020 or Irganox 1010) to this blend showed significantly improved weathering resistance. Better weathering improvement was observed when Chimassorb2020 was added. The tensile strength of PBAT/PLA/ADR/ Chimassorb2020 sample in the machine and transverse directions decreased by 8.4 and 28%, respectively, after 200 h of weathering.