Mechanical properties and biodegradability of LDPE blends with fatty-acid esters of amylose and starch

In the present article a series of low-density polyethylene (LDPE) blends w ith different amounts of fatty esters of amylose and starch, were prepared in a Haake-Buchler Reomixer. The tensile as well as the dynamic thermomecha nical (DMTA) properties of the blends were measured. It was found that as t he amount of the esters increases in the blends, the tensile strength and e specially the elongation at break decrease nonlinearly. Scanning electron m icroscopy (SEM) was used to assess the interfacial adhesion between LDPE an d the corresponding esters. The incompatibility of the blends was also veri fied with DMTA and differential scanning calorimetry (DSC). From the biodeg radation studies of the blends during exposure in activated sludge, it was found that all esters are biodegradable, although to a much lesser degree c ompared to pure strach. The biodegradation rate of the composites is relati vely small due to the low biodegradation rate of the pure esters. (C) 1999 John Wiley & Sons, Inc.