engleski

Structure and physical properties of biopolymer glass composites prepared with ionic liquids

Over the past decade, a significant research effort has been directed toward developing biopolymers obtained from renewable raw materials which would replace environmentally harmful synthetic polymers. Generally, biopolymers such as starch, cellulose, chitosan, zein, gelatin or polylactic acid (PLA) offer many benefits but their poor mechanical properties often limit their application. In order to overcome this disadvantage and produce an environmentally friendly polymer with superior physicochemical properties, various composites with different combinations of matrix biopolymer and fillings have been developed. Also, biopolymers generally have low solubility in conventional solvents, so for the preparation of biopolymer-based materials novel class of solvents called ionic liquids (IL) has been used. ILs are low-temperature molten salts composed of bulky organic cation and smaller inorganic or organic anion which are considered ideal “green” solvents for synthesis and catalysis due to their non-volatility, non-flammability, and chemical and thermal stability. In this work, we present a series of composites based on polylactic acid (PLA) and different glass fillers (bioglass, phosphate-based glasses containing various alkali and transition metal oxides, glass waste from Kelteks company) prepared using imidazolium- and pyrrolidinium-based ILs as solvents. The thermal, structural, mechanical and electrical properties of these novel composites were thoroughly studied using differential scanning calorimetry (DSC), X-ray diffraction, microscopy techniques, IR spectroscopy and impedance spectroscopy. The results show that selected ILs efficiently dissolve PLA and can be used in the preparation of PLA-glass composites with various (micro)structural and physical properties.

polylactic acid ; glass fillers ; ionic liquids

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