Properties of Compatibilized Polylactide Blend Films with Gelatinized Corn and Tapioca Starches

Blend films containing two types of starch, various amounts of methylenediphenyl diisocyanate (MDI), and polylactide were prepared. The effects of MDI level and starch type on the tensile, thermal, and morphological properties of these films were investigated. The MDI amount was varied from 0 to 10 wt % on the basis of gelatinized starch (GS) content, whereas two types of starch (corn and tapioca) were added as filters. In this study, the blend films were hot-mixed at 180 degrees C by an internal batch mixer and then compression-molded to form test specimens. The results show that the addition of MDI as a compatibilizer led to in increase in the tensile properties compared with the uncompatibilized films. Furthermore, the thermal properties indicated some improving interfacial adhesion between the two phases, as evidenced by the morphological results. These behaviors were observed in the blends with both gelatinized tapioca starch and gelatinized corn starch. The different types of starch had no effect on the glass-transition and melting-temperature Shifts, including water absorption of the blend films. On the other hand, the mechanical properties of the blends with gelatinized corn starch were higher than those of the others. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 2305-2311, 2010