When polymer fibers are manufactured by melt spinning, axial velocity is nearly uniform across any cross section but temperature and stress vary significantly across the fiber radius. Thus, the fiber solidifies from the outside in, with the fiber being solid on the outside but molten on the inside for some distance before complete solidification, and stress near solidification, the controller of mechanical properties of the spun fiber, has radial variation. We present a computationally 1D melt spinning model which recognizes the radially inhomogeneous solidification region, and computes axial and radial dependence of stress in the spinline. With this radial resolution, stress near solidification is now the stress evaluated on a surface near the solidification boundary. In simulations of melt spinning processes, we investigate features of the solidification boundary and stress near solidification, and examine how these change as material properties and process conditions change. As part of this study, we propose and investigate a solidification criterion that is a function of both stress and temperature.
© 2000, Carl Hanser Verlag, Munich