Synthesis, characterization, and biodegradability of fatty-acid esters of amylose and starch

Abstract

A series of starch and amylose esters with different degrees of substitution and side-chain length were prepared and studied. The esters were prepared by acyla- tion of the polysaccharide with the appropriate acid chlorides, such as octanoic, dode- canoic, and octadecanoic. The degrees of substitution were 0.54, 1.8, and 2.7. After preparation, the resulting esters were characterized by elemental analysis, 1 H nuclear magnetic resonance ( 1 H-NMR), Fourier transform infrared (FTIR), differential scan- ning (DSC), thermogravimetric analysis (TGA), contact angle, and water uptake mea- surements. Their mechanical properties and, in particular, the tensile strength and elongation at break depend on the side-chain length and on the degree of substitution. The extent of their biodegradability, after exposure to activated sludge, was assessed by weight loss measurements and scanning electron microscopy (SEM). It was found that these new materials are biodegradable, and the biodegradation rate decreases with increasing degree of esterification. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1440 -1451, 1999