Mechanical and Thermal Properties of Biopolyester-Lignophenol Films

Novel lignin-based polymers, lignophenols, have been derived from native lignins through the phase-separation system composed of phenol derivatives and conce ntrated acid. The molecular weight of lignophenol was controlled from ca.7400 to ca.520, using the intramolecular switching function under the alkaline condition. By the blending of the biopolyester [poly (3-hydroxybutyrate)] with butylhydroxyanisole (BHA), triacetin and lignophenol 2nd derivative, the elongation ratios of the resulting films became 5, 5 and 20 times higher, respectively, compared with the control film without additives. For the composite films with BHA and triacetin, the shrinkages and the weight losses were observed with increasing temperature, due to the evaporation of additives. On the other hand, for the composite film with lignophenol 2nd derivative, no shrinkage was observed, and the thermogravimetric profiles were almost compatible with that of the control film. The DSC analysis indicated that the crystallization enthalpies of biopolyester-lignophenols films decreased with increasing contents of lignophenols.