where f is theweight fraction of PLA in the composite, DHm
the enthalpy of melting, and DHom
is the enthalpy of
melting of 100% pure PLA taken as 93.7 J g1.[25] Addition
of the WS fibers alone or in combination with PLA-g-MA,
did not significantly change the glass transition (Tg) and
melting temperature (Tm) of the PLA, which were around
60 and 170 8C, respectively. The composites showed
decreased crystallization temperature (Tc), reduced
enthalpy of crystallization (DHc) and an increased degree
of crystallinity (x) than the neat PLA possibly due to the
nucleating activity of the WS fibers. This DSC data agree
very well with the literature, and similar observations
have been reported by Lezak et al. in which the addition of
agricultural residue (sugar beet pulp) fibers nucleated PLA
and increased its degree of crystallinity.[26] The degree of
crystallinity was higher in the compatibilized composites.
The composites exhibited lower thermal stability than
the neat PLA as shown in TGA data presented in Figure 2.
Bioplastics, including PLA are known to thermally degrade
during processing due to various depolymerization and
thermal oxidation reactions.[23] The presence of the less
thermally stable agricultural fibers might increase the
thermal degradation reactions occurring during processing
giving rise to the observed reduced thermal stability in the
composites. Similar results have been reported in the