National Textile Center Annual Report : November 1999 M 98 - G 05 1 M 98 - G 5 DRAW INDUCED MORPHOLOGY DEVELOPMENT
نویسندگان
چکیده
A recent series of papers on single-step drawing of PET film has provided the first systematic examination of the manner in which interactions of the rate of molecular relaxation, the rate of crystallization, and the rate of deformation result in specific polymer microstructures (D.R. Salem, et al., Polymer, 1992, 1994, and 1995, Macromolecules, 1995, Antech’96, Vol II). This information is being incorporated in a continuum rheology model of fiber drawing we developed last year (Ref. 1-3) that will permit prediction of microstructure evolution under conditions unavailable in conventional drawing methods. Previous studies on multistep drawing processes have been largely carried out on a trial and error basis, and have rarely involved more than three draw steps. The incremental drawing process (M. V. Sussman, Adv. Tech. 1993), used in this study, divides the drawing process into a large number of incremental draw zones, and by controlling the strain levels, temperature profiles and strain rates in each of these zones it is possible to investigate temperature and strain rate sequences that were previously inaccessible. We are using mathematical and computer simulations with experimental techniques to efficiently examine a wide spectrum of draw sequences to identify those sequences that would enhance molecular orientation to its theoretical limits. The continuum models we developed can address isothermal draw in free span and on the roller and non-isothermal draw in a two-stage draw process. Continuum models for incremental draw is under development.
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