Composites Based on Starch and Polylactide

Abstract

The blends of polylactide with starch at different component ratio are obtained under shear deformation in a Brabender mixer. The thermal behavior of polylactide composites with starch is studied by DSC, and their crystallinity is determined using X-ray diffraction; according to GPC data, the biodegradation of these composites upon exposure in the soil is quantified. An analysis of the experimental results shows that polylactide is almost incompatible with starch. A decrease in the melting point of polylactide in the composites with an increase in the starch content indicates the formation of more defective small crystals due to the difficulty of the crystallization process. On the basis of the data of X-ray structural analysis, it is shown that the total degree of crystallinity of the composites increases after exposure in the soil. This is associated with the washing out of the amorphous polylactide region under the action of water and microorganisms in the soil. Using GPC, it is shown for the first time that the biodegradation of polylactide when exposed in the soil proceeds according to the depolymerization mechanism; in the composites, this process occurs more intensely.