2D Modeling of high-speed fiber spinning with flow-enhanced crystallization

Abstract

A two-dimensional (2D) analysis of fiber spinning is presented based on a modified version of the two-phase model [Shrikhande et al., J. Appl. Polym. Sci. 100, 3240–3254 (2006); Kohler et al., J. Macromol. Sci. Phys. 44, 185–202 (2005)] that accounts for flow-enhanced crystallization (FEC). The modified model employs the extended pom-pom (XPP) constitutive equation for the amorphous phase and the rigid rod equation for the semicrystalline phase. Calculations are carried out for the high-speed spinning of nylons, polyethylene terephthalate (PET), and pure poly(L-lactic acid) (PLLA), as well as racemic mixtures of the latter (rPLA). Radial variations in temperature and degree of crystalline transformation and microstructure for the PLLA, rPLA, and higher speed PET examples show significant patterns in the skin and core regions of the fiber that reflect the interplay between FEC and thermal-induced crystallization (TIC). Insight is gained into the relationship of TIC and FEC in determining radial birefringence profiles. Likewise, similar considerations for the particular Nylon and lower speed PET examples indicate their less pronounced radial effects are the result of the same interplay.