Cold Crystallization Kinetics and Thermal Degradation of PLA Composites with Metal Oxide Nanofillers

Applied Sciences

GeorgeZ. Papageorgiou¹  Evangelia Tarani²  Konstantinos Chrissafis²  Klementina Pušnik Črešnar³  LidijaFras Zemljič³  Alexandra Zamboulis⁴  Zoi Terzopoulou⁴  Dimitrios N. Bikiaris⁴  Dimitra Lambropoulou⁵ 

[1] Department of Chemistry, University of Ioannina, P.O. Box 1186, GR45110 Ioannina, Greece;Department of Physics, Aristotle University of Thessaloniki, GR54124 Thessaloniki, Greece;Faculty of Mechanical Engineering, University of Maribor, 2000 Maribor, Slovenia;Laboratory of Chemistry and Technology of Polymers and Dyes, Department of Chemistry, Aristotle University of Thessaloniki, GR54124 Thessaloniki, Greece;Laboratory of Environmental Pollution Control, Department of Chemistry, Aristotle University of Thessaloniki, GR54124 Thessaloniki, Greece;

关键词: poly(lactic acid);    nanocomposites;    crystallization kinetics;    thermal stability;    degradation kinetics;   

DOI  :  10.3390/app11073004

来源: DOAJ

【 摘 要 】

Poly(lactic acid) (PLA) nanocomposites with antimicrobial fillers have been increasingly explored as food packaging materials that are made of a biobased matrix and can minimize food loss due to spoilage. Some of the most commonly studied fillers are zinc oxide (ZnO), titanium dioxide (TiO₂), and silver nanoparticles (AgNPs). In this work, nanocomposites with 1 wt.% of each filler were prepared by melt mixing. An extensive study of thermally stimulated processes such as crystallization, nucleation, degradation, and their kinetics was carried out using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). In detail, non-isothermal cold crystallization studies were performed with DSC and polarized light microscopy (PLM), and kinetics were analyzed with multiple equations. The activation energy of the non-isothermal cold crystallization was calculated with the methods of Kissinger and Friedman. The latter was used to also determine the Hoffman–Lauritzen parameters (K_g and U*) by applying the Vyazovkin method. Additionally, effective activation energy and kinetic parameters of the thermal decomposition process were determined by applying the isoconversional differential method and multivariate non-linear regression method. According to TGA results, metal oxide nanofillers affected the thermal stability of PLA and caused a decrease in the activation energy values. Moreover, the fillers acted as heterogenous nucleating agents, accelerating the non-isothermal crystallization of PLA, thus reducing its activation energy. It can be concluded that metal oxide nanofillers catalytically affect the thermal degradation and crystallization of PLA samples.

【 授权许可】

Unknown