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Synthesis, characterization, and thermal stability of poly (lactic acid)/zinc oxide pillared organic saponite nanocomposites via ring‐opening polymerization of d , l ‐lactide
Author(s) -
Zhen Weijun,
Zheng Youya
Publication year - 2016
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.3727
Subject(s) - saponite , materials science , thermal stability , thermogravimetric analysis , polymerization , polymer chemistry , gel permeation chromatography , lactide , nanocomposite , differential scanning calorimetry , chemical engineering , polymer , composite material , montmorillonite , engineering , physics , thermodynamics
Poly (lactic acid) (PLA) was synthesized using d , l ‐lactide monomer and zinc oxide (ZnO) pillared organic saponite as the green catalyst, through ring‐opening polymerization. The effects of stoichiometry of catalyst and polymerization conditions on molecular weight of PLA were evaluated by orthogonal experiment. The optimum polymerization parameters were: 0.5 wt% ZnO pillared organic saponite and reaction conditions of 170°C for 20 hr. Fourier transform infrared spectroscopy and 1 H nuclear magnetic resonance spectroscopy confirmed the PLA structure. Gel permeation chromatography showed that the average molecular weight of PLA was 48,442 g/mol, and its polydispersity index was 1.875. Differential scanning calorimetry, X‐ray diffraction, and polarized optical microscopy showed that ZnO pillared organic saponite improved the crystallinity of PLA. Thermal gravimetric analysis showed improved thermal stability of PLA because of ZnO pillared organic saponite. Thermal decomposition kinetics of PLA/ZnO pillared organic saponite nanocomposites was also studied. The activation energies ( E a ) for thermal degradation of PLA and PLA/ZnO pillared organic saponite nanocomposites were evaluated by the Kissinger and Ozawa methods, which demonstrated that ZnO pillared organic saponite enhanced E a of thermal degradation of PLA and significantly improved its thermal stability. Copyright © 2015 John Wiley & Sons, Ltd.