Poly(L-lactic acid) composites with flax fibers modified by plasticizer absorption

The effect of modified flax fibers by plasticizer absorption in poly(L-lactic acid) composites was investigated. The plasticizes chosen were triethyl citrate (TEC), tributyl citrate (TBC) and glycerol triacetate (GTA), which were derived from natural sources. Characterization was performed by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The morphology was examined from scanning electron microscopy (SEM) and optical microscopy (OM). The results showed that the plasticizer caused a marked increase in the storage modulus of the composites, which could be due to an improvement in the morphology of the matrix and a smoother surface coverage of the fibers by the matrix. The thermal properties were also affected, in which the glass transition temperature (Tg), the crystallization temperature (Tc) and the crystallinity (Xc) were reduced depending on the plasticizer. The citrate esters revealed to be the most effective plasticizers of those tested.