Cooling rate effects on the crystallization kinetics of polypropylene/date palm fiber composite materials

Non-isothermal crystallization kinetics of polypropylene/date palm fiber (PP/DPF) composite materials were investigated in this study, using the differential scanning calorimetry (DSC) method. Different fiber contents and cooling rates, varying from 2.5°C/min to 20°C/min, were considered. The obtained results indicated that the initial crystallization temperature increases with the increase of the DPF content. This was attributed to the nucleating ability of these fibers. Several theoretical models were used to predict the non-isothermal crystallization kinetics of the materials considered in this study. Basically, it was shown that both the Avrami analysis, modified by Jeziorny, and the method developed by Mo could adequately describe such kinetics. The activation energies required during the overall crystallization process and at different amounts of the relative degree of crystallinity were also evaluated using the Kissinger method and the isoconversional analysis of calorimetric data, respectively. It was shown that the presence of the DPFs in the PP matrix decreases these energies, confirming their nucleating ability during the non-isothermal crystallization process.