Nucleation agent was added to the supercooled polymer melt to increase the number of formed folded chain polyethylene crystalline nuclei. Kinetic model of nucleation on active centers is modified to include exhaustion of the active centers via modified boundary condition in contrast to the standard Avrami model, where addition equation describing such a process is needed [1, 2].

The basic characteristics of nucleation process (the size distribution of nuclei, the total number of nuclei, and nucleation rate) were determined by numerical solution of kinetic equations and compared with measured data. It seems that the total number of nuclei, Z_i, greater than some detectable size i increases after some time delay linearly with time. However nucleation rate, J_i = dZ_i/dt, after reaching some maximum, which is lower than stationary nucleation rate J^S, decreases with time and as a consequence Z_i is not linear in time (Fig. 1). It is caused by exhaustion of active centers during phase transition.

This work was supported by the Czech Science Foundation (Grant No. P108/12/0891).

[1] Z. Kožíšek, M. Hikosaka, K. Okada, and P. Demo, J. Chem. Phys. 134, 114904 (2011).

[2] Z. Kožíšek, M. Hikosaka, K. Okada, and P. Demo, J. Chem. Phys. 136, 164506 (2012).

Fig. 1. Dimensionless nucleation rate, J_i/J^S, for nucleus size i = 500 (full line) and 30000 (dashed line) as a function of time.

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