Crystallization and Melting Behavior (DSC): The presence of RHF showed significant effects on the cooling behavior of the composites. The DSC thermograms obtained during cooling are shown in Figure 4. Only one exothermic peak was registered for all the samples. For PP processed without
RHF the crystallization peak was observed at Tc=113oC while for the composites these exothermic peaks shifted to higher temperatures in all cases. The determined Tc values are shown in Table I. The higher Tc values of the composites indicate that the crystallization is favored in the presence of the rice husk particles. The Tc increase can be considered to be due to the nucleation effect of the rice husk: fibers act assites for heterogeneous nucleation thus inducing the crystallization of the matrix. 1,16 Figure 5 shows the heating thermograms of selected samples obtained from the second heating range. For both neat PP and PP/RHF composites only one single endothermic peak was observed at similar temperatures (near 164 oC), corresponding to the melting of the α-crystalline phase of the PP sequences. These results indicate that the presence of