Coexistence of melting and growth during heating of a semicrystalline polymer.

The coexistence of melting and growth during heating is observed by molecular dynamics simulations of semicrystalline entangled polymers. During heating, some microcrystalline domains (MCDs) are melted while others are still growing, which can be associated with multiple-peaked melting endotherms. The growth of MCD's stability is related to the increase of molecular disorder. The increasing of the stem length during annealing close to the melting point is contributed by the orientational correlation in the semimelted surface regions while direct trans-trans states are decreasing which increases the flexibility and mobility of the crystalline stems.