No abstract

No abstract

Granular tapioca was thermally blended with poly(lactic acid) (PLA). All blends were prepared using a plasti-corder and characterized for tensile properties, thermal properties and morphology. Scanning electron micrographs showed that phase separation occurred, leading to poor tensile properties. Therefore, methylenediphenyl diisocyanate (MDI) was used as an interfacial compatibilizer to improve the mechanical properties of PLA/tapioca blends. The addition of MDI could improve the tensile strength of the blend with 60 wt% tapioca, from 19.8 to 42.6 MPa. In addition, because PLA lacked toughness, acetyl tributyl citrate (ATBC) was added as a plasticizer to improve the ductility of PLA. A significant decrease in the melting point and glass-transition temperature was observed on the basis of differential scanning calorimetry, which indicated that the PLA structure was not dense after ATBC was added. As such, the brittleness was improved, and the elongation at break was extended to several hundred percent. Therefore, mixing ATBC with PLA/tapioca/MDI blends did exhibit the effect of plasticization and biodegradation. The results also revealed that excessive plasticizer would cause the migration of ATBC and decrease the tensile properties.

Blends of the biodegradable polycaprolactone (PCL) and multiwalled carbon nanotubes (MWNTs) were prepared by means of a melt blending method. To conquer the poor compatibility between PCL and MWNTs, the acrylic acid grafted polycaprolactone (PCL-g-AA) and the multihydroxyl functionalized MWNTs (MWNTs-OH) were used as alternatives for the preparation of blends. As the comparison between PCL-g-AA/MWNTs-OH and PCL/ MWNTs blends, the former gave much better thermal and mechanical properties than the latter; for examples, 77 C increase in the initial decomposition temperature and 13.3MPa in the tensile strength at break with the addition of only 5 wt %, due to the formation of ester groups through the reaction between carboxylic acid groups of PCL-g-AA and hydroxyl groups of MWNTs-OH. Finally, the optimal amount of MWNTs-OH was 5 wt % because excess MWNTs-OH caused separation of the organic and inorganic phases and lowering their compatibility.

No abstract