The growing need for developing biodegradable materials has drawn both industrial and academic interests in agricultural applications. In this presentation, polyhydroxyalkanoate (PHA)/poly(butylene adipate-co-terephthalate) (PBAT) biocomposite mulch films were prepared from the 20/80 w/w blends of PHA/PBAT via twin screw extrusion. The degradation process of films were studied by different characterization methods after the films underwent accelerated xenon arc aging test. As revealed by the retention rate (RE) of elongation at break (εb), the blending of PHA into PBAT notably decreased the mechanical property stability of PBAT. Moreover, by adding different types of stabilizers (light stabilizers, UV absorbers, and antioxidants), the mulch films showed significantly improved retention of mechanical performance after aging. After 100 h of xenon arc test, the RE of the PBAT-PHA film with 0.3% UV absorber(PBAT-PHA-UV) is the highest (RE = 47%) among all the samples, as compared to the PBAT-PHA film without any stabilizer (RE = 3.6%). The evolution of morphology changes of both PBAT-PHA and PBAT-PHA-UV films at different aging times was observed by SEM. The results suggested that the surface of PBAT-PHA films underwent partial cleavage of the outer layer, followed by the formation of cavities, and finally the cavities converged into larger defects. Adding UV stabilizer appeared to “slow down” that process. As suggested by DSC results, with the increase of aging time, both the crystallization temperature (Tc) and melting temperature (Tm) of PBAT-PHA decreased significantly and the peak broadened, indicating the transformation of the crystal structure and reduction of crystallinity. After adding different stabilizers, the decrease of Tc was less proounced. Moreover, the crystal structure of PBAT-PHA after accelerated aging test was proved to be damaged based on XRD results. And the ATR-FTIR results indicated that the PBAT-PHA mulch films underwent hydrolysis and photodegradative chain scission (Norrish Type II reaction) reactions. This study has provided some insights to understand the degradation mechanisms of the PHA/PBAT biodegradable composite mulch films.

Understanding the degradation process of polyhydroxyalkanoate (PHA)/ poly(butylene adipate-co-terephthalate) (PBAT) biocomposite mulch films and the effects of stabilizers under accelerated aging test

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.