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Multiwalled carbon nanotubes (MWNT) were functionalized with poly(L-lactic acid) (PLLA) with different molecular weights using a "grafting to" technique. The oxidized MWNT (MWNT-COOH) were converted to the acyl-chloride-functionalized MWNT (MWNT-COCl) by treating them with thionyl chloride (SOCl2) and reacting them with PLLA to prepare the MWNT-g-PLLA. FTIR and Raman spectroscopy revealed that the PLLA was covalently attached to the MWNT, and the weight gain due to the functionalization was determined by thermogravimetric analyses (TGA). The Raman signals of the MWNT were greatly weakened as a result of the PLLA grafting. The morphology of the grafted PLLA was examined by using SEM and TEM. The amount of grafted PLLA depended on the molecular weight of the PLLA. The PLLA coated on the MWNT became thicker and more uniform with increasing PLLA molecular weight from 1000 to 3000. However, the amount of grafted PLLA became lower when the molecular weight of PLLA was further increased to 11,000 and 15,000, and the PLLA attached to the MWNT showed a squid leglike morphology forming blobs and leaving much of the MWNT surface bare.

In the present study, cellulose whiskers were incorporated into nanofibers of polyethylene oxide (PEO) by the electrospinning process to enhance the mechanical properties of the electrospun PEO fibers. Cellulose whiskers consisting of highly crystalline rod-like particles with a high aspect ratio and specific area were obtained by the acid hydrolysis of bacterial cellulose microfibrils. From the transmission electron microscopy (TEM) images of the bacterial cellulose whiskers, their length was measured to be 420 AE 190 nm and their width 11 AE 4 nm. The height of the whiskers was measured to be 10 AE 2 nm by atomic force microscopy. The successful formation of electrospun fibers with a diameter of less than 1 mm and well-embedded microfibrils was confirmed by scanning electron microscopy and TEM.

Poly(L-lactide) (PLA) was melt-mixed with micrometer-sized and nanosized calcium carbonate (CaCO 3 ) particles before and after modification with calcium stearate. Adhesion between the CaCO 3 particles and the PLA matrix was assessed qualitatively by scanning electron microscopy observation of the fractured surface morphology of the composites. The effect of the incorporation of the CaCO 3 particles on the thermal stability of the PLA-based composites was quantified by the temperatures corresponding to 5 and 50% of weight loss and the activation energy determined through thermogravimetric analyses of the composites. The tensile strength and modulus values of the composite were improved greatly without a significant loss in the elongation at break when the nanosized CaCO 3 was incorporated up to 30 wt %.