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Poly(D,L-lactide) synthesis using tin(II) 2-ethylhexanoate initiated ring-opening polymerization (ROP) takes over 30 hours in bulk at 120 °C. The use of microwave makes the same bulk polymerization process with the same initiator much faster and energy saving, with a reaction time of about 30 minutes at 100 °C. Here, the poly(lactide) synthesis was done in a microwave reactor, using frequency of 2.45 GHz and maximal power of 150 W. The reaction temperature was controlled via infra-red system for in-bulk-measuring, and was maintained at 100 °C. Different molar ratios of monomer and initiator, [M]/[I], of 1,000, 5,000 and 10,000 were used. The achieved average molar masses for the obtained polymers (determined by gel permeation chromatography) were in the interval from 26,700 to 112,500 g/mol. The polydispersion index was from 2.436 to 3.425. For applicative purposes, the obtained material was purified during the procedure of microsphere preparation. Microspheres were obtained by spraying a fine fog of polymer (D,L-lactide) solution in tetrahydrofuran into the water solution of poly(vinyl alcohol) with intensive stirring.

Composite films based on poly(lactic acid) filled by 0.5 and 5 wt.% of Allium ursinum extract (wild garlic) for food packaging applications were prepared. Obtained films were examined from the view of characterization material properties and antimicrobial potential. The addition of two different amounts of A. ursinum extract improved thermal and mechanical properties of neat PLA (increase in T g and tensile strength for both loadings). The oxygen barrier properties of the obtained hybrid films in dry condition were not significantly modified, while a slight increase of oxygen transmission rate was observed for the 5% loaded samples. Differences were detected in DE* values among the films containing A. ursinum extract in comparison with neat PLA. A marked difference between neat PLA and sample with 0.5 wt% of A. ursinum extract (3-6) was observed, while the color of the samples with 5 wt% was characterized by a completely different shade compared with neat PLA (>12). The antimicrobial activity of PLA films (neat and with 0.5 and 5 wt% of A. ursinum extract) was tested against Gram-negative bacterium Escherichia coli and both polymer composites with 0.5 and 5 wt% AU extract showed antimicrobial activity. POLYM. COMPOS., 00:000-000,

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