Abstract
Poly(lactic acid) or PLA was synthesized by direct condensation polymerisation of lactic acid. Polymerisation was carried out with tin(II) chloride as a catalyst and diphenyl ether as solvent. The obtained PLA was characterised by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (1H-NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The effects of reaction temperature and reaction time on molecular weight of PLA were investigated. The molecular weight of PLA increased with increasing polymerisation temperature. The highest molecular weight which was about 2×105 g/mol was obtained at 180°C for 16 hrs at low reaction pressure. In addition, thermal properties, i.e. Tm and Tg, became decreased as reaction temperature increased. On the other hand, both molecular weight and thermal properties increased as longer polymerisation time proceeded.
Keywords
Poly(lactic acid), Polycondensation, Biopolymer.
Citation
P. LAONUAD, N. CHAIYUT, B. KSAPABUTR, Poly(lactic acid) preparation by polycondensation method, Optoelectronics and Advanced Materials - Rapid Communications, 4, 8, August 2010, pp.1200-1202 (2010).
Submitted at: March 9, 2010
Accepted at: Aug. 12, 2010