Diffusion Control of Crystallization

Using the same polymer solution as in Fig. 3.78 for analysis of the crystal growth at lower temperature, the growth rate slows with time, as shown in Fig. 3.79. The crystal growth slows because the diffusion limits the number of crystallizable molecules in 

Crystal Growth of Polyethylene grown from 0.01% solution in xylene Crystallization Temperature 353.2 K  

The solvent concentration, s, changes with distance, n, from the crystal and with time, t, until steady state is reached, as indicated on the left in Fig. 3.80. The equation for s involves a competition of the growth of the crystal in direction of lower solvent 

Schematic of the Solvent Concentration in Front of a Growing Crystal 

The supercooling is sufficiently large to increase the growth rate at the crystal tips due to diffusion control 

---