Dresden 2017 – wissenschaftliches Programm
CPP 40.9: Hauptvortrag
Mittwoch, 22. März 2017, 17:45–18:15, ZEU 222
The Role of Entanglement in Polymer Crystallization — •Chuanfu Luo — Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1 OT Golm, 14476 Potsdam, Germany
Polymer crystallization is one of the fundamental topics in polymer science. A deeper understanding of it has a great industrial importance as about 70% industrial plastics are of semicrystalline states. We carried out large scale MD simulations of polymer crystallization by using a coarse-grained poly(vinyl alcohol) (CG-PVA) model. We simulated different situations for linear polymers such as of dense melts, of concentrated solutions, under confinement of two walls, and under steady shears. We analyzed the entanglement states before the crystallization by using primitive path analysis (PPA) and its geometric analogue, the Z1 method. We found that the crystallization behavior is strongly related to the initial entanglement states. The crystalline stem length (d) is directly controlled by the initial entanglement length (Ne). The slow relaxation of entanglement state can be a major reason for the thermal memory effect. We found a roughly linear relation of d=Ne/f for most cases, where f means an effective folding number with a value about 2.5 for dense melts or slightly larger for concentrated solutions. We propose that thickness selection in polymer crystallization is mainly restricted by the initial entanglement length. Our simulations may provide a novel approach to understand polymer crystallization at different situations.