PLA/clay/wood nanocomposites: nanoclay effects on mechanical and thermal properties

Poly(lactic acid) (PLA)/clay/wood nanocomposites were prepared by melt extrusion of PLA, nanoclay, and wood flour (WF). The clay particles exhibit an intercalated structure in the PLA matrix and the addition of WF slightly increases the spacing in the galleries of the intercalated structure. The intercalated clay particles and WF in the PLA matrix restrict the motion of the PLA molecules and crystals. The tensile and flexural moduli of PLA/clay/wood nanocomposites with 30 wt% WF, respectively, increase from 3.75 to 7.08 GPa and from 3.83 to 6.01 GPa compared to neat PLA by adding up to 5 wt% nanoclay. Voids around clay particles, observed via scanning electron microscopy are associated with the negative effect of the clay particles on the interfacial adhesion between the WF and the PLA matrix. Clay particles improve the thermal decomposition temperature (T(d)) of PLA/clay/wood nanocomposites by about 10 degrees C compared to that of PLA/wood composites. The effects of clay particles on other thermal properties such as glass transition temperature (T(g)), melting temperature (T(m)), and linear thermal expansion are also discussed in this article.