(201c) The Role of Flow-Enhanced Crystallization in the Dynamics of Fiber Spinning

The dynamics of melt fiber spinning have been modeled using a two-phase constitutive model that includes the effects of flow-enhanced crystallization (FEC) on the process. Calculations under low-and high-speed spinning conditions suggest diferent influences of the crystallization on the sensitivity and stability of the process. At low spin speeds where FEC effects are negligible, the sensitivity is predicted to decrease with increasing cooling and this trend is also shown to be consistent with increased crystallinity. Comparisons with sensitivity data for low-speed spinning of iPP demonstrate that incorporation of crystallization effects inherent in our two-phase model leads to improved predictions of the magnitude and trends with perturbation frequency for both Giesekus and XPP amorphous phase constitutive equations. Since higher spinline cooling also equates with higher crystallization, a further separation of the three conditions is observed as cooling air temperature is decreased. At very high spin speeds where significant FEC and increased levels of crystallization are predicted, the trend of higher crystallization improving sensitivity does not necessarily hold