A simplified two-dimensional model of the melt spinning of semi-crystalline hollow compound fibers
- 作者：Francisco J. Blanco-Rodrí ; guez fjblanco@lcc.uma.es ; J.I. Ramos ; jirs@lcc.uma.es ;
- 关键词：Hollow compound fibers ; Newtonian rheology ; Crystallization ; Avrami&ndash ; Kolmogorov model ; Doi&ndash ; Edwards theory ; Molecular orientation tensor
- 刊名：International Journal of Thermal Sciences
- 出版年：2012
- 期刊代码：94_12900729
- 类别：et
- 出版时间：August, 2012
- 卷：58
- 期：Complete
- 页码：102-112
- 文件大小：840 K
摘要
A two-dimensional model of the melt spinning of semi-crystalline hollow compound fibers is presented. The model accounts for the orientation of the polymer molecules by means of a Doi-Edwards formulation for the molecular orientation tensor, and for the crystallization of the polymer by means of the Avrami-Kolmogorov kinetics with a modification for the flow-induced crystallization, and uses a Newtonian rheology where the dynamic viscosity is a function of the temperature, molecular orientation and degree of crystallization. The model is based on the leading-order one-dimensional equations for the fiber's geometry and axial and radial velocity components determined from an asymptotic analysis of slender fibers at low Reynolds numbers, and two-dimensional equations for the temperature, molecular orientation tensor and crystallization. It is shown that almost complete molecular orientation is achieved close to the maximum swell cross-section due to the large contraction of the fiber there, whereas, for the conditions considered here, the ultimate degree of crystallization is not achieved at the take-up cross-section. It is also shown that there are non-uniformities in the temperature and crystallinity profiles at the take-up cross-section which may have an effect on the fiber's properties.