Mechanical and thermal properties of poly(L-lactide) incorporating various inorganic fillers with particle and whisker shapes

Full Paper: Poly(i-lactide) (PLLA) composites incorporating various inorganic fillers (ifR-PLA) were prepared by the melt blending techniques, and their mechanical and thermal properties were evaluated. The filler types influenced the mechanical properties of ifR-PLA; for those incorporating particle and whisker-type fillers the tensile moduli were 3.1-3.7 and 3.7-4.5 GPa, respectively, and the flexural moduli were 4.1-4.8 and 4.8-6.1 GPa. It was found that the tensile strength and modulus, as well as the flexual modulus, of ifR-PLA incorporating whisker-type fillers increased in proportion to the volume percent of the fillers (V-f). The flexual strength of ifR-PLA incorporating 9Al(2)O(3).2B(2)O(3) whiskers showed a similar increase, while that of ifR-PLA incorporating CaCO3 whiskers showed a decrease with increasing V-f. This difference may be because the 9Al(2)O(3).2B(2)O(3) with its large aspect ratio kep its original fibrous shape, while the CaCO3 lost it fibrous shape during the blending process. However, the reinforcing of these fillers was relatively low compared with that known for the corresponding composites of the conventional polymeric materials, probably because of the poor surface adhesion of PLLA to the fillers.