RUAN Chunlei, LIU Chuntai. Numerical simulation of morphology and kinetics of polyethylene in shear flow[J]. CIESC Journal, 2016, (5): 2144-2151.
DOI:
RUAN Chunlei, LIU Chuntai. Numerical simulation of morphology and kinetics of polyethylene in shear flow[J]. CIESC Journal, 2016, (5): 2144-2151.DOI: 10.11949/j.issn.0438-1157.20151472.
Numerical simulation of morphology and kinetics of polyethylene in shear flow
The mathematical model of morphology evolution of spherulites and shish-kebabs in the shear flow is deduced based on the Eder model. The model considers that the nucleation and growth of spherulites are determined by the static temperature
while the nucleation and growth of shish-kebabs are determined by the flow
which is depended on the first normal stress difference of the system and the shear rate respectively. In order to calculate the nucleation density of the shish-kebabs
the two-phase suspension model of Zheng is introduced. The model treats the stress as the combination of the amorphous phase and semi-crystalline phase. The amorphous phase is described by FENE-P model while the semi-crystalline phase is depicted by a rigid dumbbell model. Based on the mathematical model
the Monte Carlo method and the finite difference method are constructed
respectively. The former is to capture the crystal growth while the latter is to calculate the equation of the system. By using these methods
the 2D crystallization in the shear flow is simulated. The evolution of spherulites and shish-kebabs is given. Also
the effects of shear time and shear rate on the nucleation density of shish-kebabs
crystallization rate
the viscosity of the fluid and the system stress are discussed. Numerical results show that the Monte Carlo method is valid which not only captures the morphology evolution of crystals successfully
but also predicts the crystallization rate well. In addition
the increase of the shear time or the shear rate will increase the nucleation density of shish-kebabs and the crystallization rate.