Flow-Induced Phase Separation and Crystallization in Entangled Polyethylene Solutions under Elongational Flow

MHN Sefiddashti and BJ Edwards and B Khomami, MACROMOLECULES, 53, 6432-6451 (2020).

DOI: 10.1021/acs.macromol.0c00508

Flow-induced phenomena in entangled solutions of linear C1000H2002 polyethylene dissolved in n-hexadecane and benzene solvents were simulated via nonequilibrium molecular dynamics at concentrations of 14.5C* and 13.5C*, respectively, of the coil overlap concentration, C*. The simulations revealed that both solutions undergo a chemical phase separation when subject to planar extensional flow at extension rates faster than the inverse Rouse time of the solution. The onset of phase separation initiated after roughly two Hencky strain units of deformation for both solutions and attained a stationary state at about ten Hencky strain units. Furthermore, the simulations revealed that at very high extension rates the polymer phase forms semicrystalline domains regardless of the solvent; however, the critical extension rate for flow-induced crystallization appeared to be affected by a number of variables, including solution temperature and the chemical nature of the solvent.

Return to Publications page