Biodegradable polymer blends of Poly(L-lactic acid) and gelatinized starch

Gelatinized starches were prepared with various content of glycerol and wer e investigated in terms of the effect of the glycerol addition on character istics of starch and its blends. Poly (L-lactic acid) (PLA) with various ra tios of linear/star shaped PLA and starch gelatinized with various ratios o f water/glycerol were melt-blended by using twin screw mixer. The blends we re characterized by DSC thermal analysis, tensile test and morphological an alysis. Gelatinization of starch was found to lead to destruction or diminu tion of hydrogen bonding in granules and a decrease of crystallinity of sta rch. DSC data showed that starch played a role as a nucleating agent and gl ycerol as plasticizer contributed to an improvement in crystallinity in PLA . blends. When the content of starch increased, the size of spherulites in PLA blends was smaller and less regular. In the case of PLA/pure starch ble nds, the voids appeared, which were formed by the separation of starch part icles from the matrix. But for PLA/gelainized starch blends, these voids we re not observed. In the case of blends with linear PLA and starch gelatiniz ed with water/glycerol ratio of 100/40, the greatest superiority of mechani cal properties was shown and the toughness was improved compared with PLA/p ure starch blends.