ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Ageing of plasticized poly(lactic acid)/poly(β-hydroxybutyrate) blend films under artificial UV irradiation and under real agricultural conditions during their application as mulches‡

Katarína Mosnáčková, Alena Šišková, Ivica Janigová, Jozef Kollár, Miroslav Šlosár, Štefan Chmela, Pavol Alexy, Ivan Chodák, Ján Bočkaj, and Jaroslav Mosnáček

Polymer Institute, Slovak Academy of Sciences, Dúbravská cesta 9, 845 41 Bratislava, Slovakia

E-mail: katarina.mosnackova@savba.sk

Abstract: The paper is aimed on the investigation of natural ageing of plasticized poly(lactic acid)/poly(β-hydroxybutyrate) PLA/PHB blend films during their one-season application as mulches under real field conditions in the western part of Slovakia. Acetyl tributyl citrate (ATBC) was used as the plasticizer. The analysis was performed on three differently exposed parts of the foil: i) buried in soil, ii) exposed to sunlight, and iii) shadowed by plants. In parallel, UV irradiation of the blend under laboratory controlled conditions (constant temperature of 30°C and relative humidity of 55 %) was carried out. The degradation effect was followed by changes in the molar mass, chemical and crystalline structures, as well as in thermal and mechanical properties. The ternary PLA/PHB/ATBC blend lost its tensile properties faster when buried in soil than when exposed to sunlight. This result is in agreement with the data obtained for the UV-irradiated materials. Young’s modulus values showed a significant mechanical degradation under the UV irradiation as well as during natural ageing. The study was also focused on the influence of mulches on the yield and quality of sweet pepper production, characterized by carotenoids and vitamin C content.

Keywords: natural ageing – PLA/PHB blend – mulching foil – degradation – UV irradiation – crops yield

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2016-0043

Chemical Papers 70 (9) 1268–1278 (2016)