What selects lamellar thickness in polymer crystals
In plain words
When long polymers crystallize they fold back and forth into thin plates called lamellae, about 100 Angstrom thick. Which process fixes this thickness and the growth speed is disputed among competing theories.
Precise statement
Flexible polymers crystallizing from melt or solution form chain-folded lamellae of thickness l around $1e-6\,\mathrm{cm}$, with $\ell \sim 1 / (T_m^{0} - T_c)$, where $T_m^{0}$ is the equilibrium melting temperature and $T_c$ the crystallization temperature. Lauritzen-Hoffman secondary nucleation, Sadler-Gilmer rough-surface growth and Strobl's mesomorphic-intermediate model give different mechanisms. Determine which mechanism selects l and the growth rate $G(T_c)$, by direct observation of the growth front in simulations of realistic chains or in situ scattering and microscopy.
What would settle it
Molecular-resolution observation of the growth front that identifies the rate-limiting step and reproduces $l(T_c)$ and $G(T_c)$ for a specific polymer.