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This study concerns the improvement and enhancement of the properties of poly(L-lactic acid) (PLLA) through simple solution blending of pure PLLA with different kinds of biodegradable polymers. Synthesized PLLA was blended with synthesized poly(D,L-lactic acid) (PDLLA) or poly(ethylene glycol) (PEG) at various composition ratios in a solvent mixture of dichloromethane/ethanol at room temperature to produce dipolymer. The polymer-blend properties were analyzed using FTIR, DSC, UTM data and an enzymatic degradation test was conducted. It was found that PLLA blend films were obtained with limitation of the second polymer content up to 20% (w) through solvent casting. From the DSC data, two different melting temperature peaks showed that stereocomplex formation occurred during polymer precipitation for all PLLA/PDLLA blends, while only one single melting temperature peak appeared in the PLLA/PEG blend. Regarding the mechanical properties, the PLLA/PEG blend showed better performance with an improvement of the mechanical strength by around 11.18% and an improvement of the elongation at break by around 89% compared to pure PLLA. Furthermore, after the 48-hour enzymatic biodegradability test, the PLLA/PEG blends showed improvement of biodegradability with 21.88% of sample weight-loss compared to 2.53% for pure PLLA. [ABSTRACT FROM AUTHOR]

Production of biodegradable polylactic acid (PLA) from biomass-based lactic acid is widely studied for substituting petro-based plastics or polymers. This study investigated PLA production from commercial lactic acid in a batch reactor by applying a direct melt polycondensation method with two kinds of catalyst, γ-aluminium(III) oxide (γ-Al2O3) or zinc oxide (ZnO), in reduced pressure. The molecular weight of the synthesized PLA was determined by capillary viscometry and its structural properties were analyzed by functional group analysis using FT-IR. The yields of polymer production with respect to the theoretical conversion were 47% for γ-Al2O3 and 35% for ZnO. However, the PLA from ZnO had a higher molecular weight (150,600 g/mol) than that from γ-Al2O3 (81,400 g/mol). The IR spectra of the synthesized PLA from both catalysts using polycondensation show the same behavior of absorption peaks at wave numbers from 4,500 cm-1 to 500 cm-1, whereas the PLA produced by two other polymerization methods -- polycondensation and ring opening polymerization -- showed a significant difference in % transmittance intensity pattern as well as peak area absorption at a wave number of 3,500 cm-1 as --OH vibration peak and at 1,750 cm-1 as -C=O carbonyl vibrational peak. [ABSTRACT FROM AUTHOR]