Preferred fold lengths in polymer crystals: Predictions of minima in growth rates.

The unprecedented observation of a series of minima in crystal growth rates as function of undercooling is analyzed with a rate equation approach, which shows that the minima can be the result of an entropy barrier which inhibits growth. The row of stems model represents crystals of long chain paraffins in two dimensions, with additions and removals only allowed at the end of the row. The crystallization can then be represented as a sequential process, and the the rate equations can be solved to any required precision.