Direct condensation polymerization of lactic acid

In order to synthesize the higher molecular weight poly(lactic acids) by direct condensation polymerization of lactic acid, dipentaerythritol was used as a chain branching agent. Poly(lactic acids) of high molecular weight, 67000(Mn), was obtained by using antimony trioxide catalyst with good color. This poly(lactic acids) showed Tg of 54.8 °C, Tm of 147 °C and cold crystallization temperature of 115 °C. The polymer could be melt processed into transparent films. Tensile modulus of 311 Kg/ mm 2 , tensile strain of 21% and tensile strength of 12.41 Kg/ mm 2 were obtained for film collected at 400%/min and drawn 4 times.