| Abstract: | The esterification of poly(γ-glutamic acid) (γ-PGA) produced by Bacillus subtilis F2-01 with alkyl halides was carried out at 60°C in N-methyl-2-pyrrolidinone (NMP) in the presence of sodium bicarbonate to obtain the corresponding esterified γ-PGA. The thermal properties of these γ-PGA esters were examined by differential scanning calorimetry and thermogravimetry. γ-PGA esters were more stable than free acid type γ-PGA, which decomposed at 210°C. Melting temperature (Tm) of γ-PGA esters could be observed at 230-250°C. Tm of γ-PGA n-alkyl esters reached a maximum at an alkyl chain length of n = 3. © 1995 John Wiley & Sons, Inc. |
