CRYSTALLIZATION KINETICS OF LONG-CHAIN N-ALKANES FROM THE MELT AND FROM SOLUTION

The crystallization kinetics of the n-alkanes C168H338, C192H386, and C240H482 have been studied for the structures formed from either the pure melt or solution. For all the n-alkanes studied, and independent of the crystallization medium, the rate of crystallization decreases rapidly with increasing temperature. A discontinuity is observed in the temperature interval where a specific type of folded structure is no longer formed from the original melt or solution. The effect of concentration was also analyzed for the n-alkane with 168 carbons. Decreasing concentration decreases the rate of recrystallization but the functional dependence with temperature is maintained. To analyze the kinetics of the crystallites formed from the initial state, distinction needs to be made between these structures and those transformed from them. If this distinction is not made, the results could show an inversion in the rate of crystallization. The nucleation process of either folded or extended crystallites is found to be the same and shows characteristics similar to those found in the low molecular weight polymers.