Model melt spinning

George, H. H., Model of steady state melt spinning at intermediate take-up speeds, presentation given at the Joint Meeting of the US and Japanese Rheological Societies, Kona, HI, 6-9 April, 1979. 

Fig. 14.5 Morphological model of structures developed in as-spun HDPE. Take-up velocities are (a) very low (b) low (c) medium and (d) high. [Reprinted by permission from J. E. Spruiell and J. L. White, Structure Development during Polymer Processing Studies of the Melt Spinning of Polyethylene and Polypropylene Fibers, Polym. Eng. Set, 15, 660 (1975).]...

A. K. Doufas, A. J. McHugh, and C. Miller, Simulation of Melt Spinning Including Flow-induced Crystallization. Part I. Model Development and Predictions, J. Non-Newt. Fluid Meek, 92, 27-66 (2000). 

George, H. H., Model of steady state melt spinning at intermediate take-... 

There are many objectives in modeling the melt spinning process the three most pertinent are ... 

A cartoon of this model of morphology and molecular chain topology development in melt spinning of PET is shown in Figure 1.6. 

The detailed proof of this conceptual model is difficult experimentally, although it is generally supported by the existing experimental data and melt spinning process model. The overall veracity of the model is less important than the utility of the model in predicting process-structure-property relationships. Important implications of the model are as follows ... 

In the present paper a kinetic theory of crystal nucleation is considered for the polymers subjected to time-dependent deformation rates, with transient effects of the chain relaxation. The considerations provide a theory useful in modelling fast polymer processing with stress-induced crystallization, like high-speed melt spinning, melt blowing, electro-spinning, etc. 

Doufas AK, Dairanieh IS, McHugh AJ (1999) A continuum model for flow-induced crystallization of polymer melts. J Rheol 43 85-109 Doufas AK, McHugh AJ, Miller C (2000) Simulation of melt spinning including flow-induced crystallization. Part I. Model development an predictions. J Non-Newtonian Fluid Mech 92 27-66... 

Fig. 8. Comparison of model calculations of diameter attentuation, birefringence, and temperature profiles with pilot plant data for melt spinning of 0.65 IV poly(ethylene ter-phthalate) at a take-up speed of 5947 m/min. Reproduced from Ref. 33. Courtesy of the Society of Rheology.

Develop the appropriate equations needed to model a melt-spinning process that would use the behavior to increase the fiber s molecular weight during spinning. 

Several of functional Fe(III)- and Co(II)-phthalocyanines and their polymers as models for catalase, peroxidase, oxidase and oxygenase enzymes were synthesized ([265] and references cited therein). Copolyesters 62 containing Fe(III)- and Cu(II) phthalocyanines were obtained by polycondensation of phthalocyanine dicarboxylic acid dichlorides with terephthalic acid dichloride and aliphatic diols. Green or blue colored fibres could be obtained by melt spinning of the copolyesters containing below 1 mol% of the metal complex [265]. The polymers were investigated as catalysts for the thiol oxidation. 

Data on extensional stresses in fiber melt spinning, and their constitutive modeling for both isothermal and nonisothermal fiber spinning, can be found in the several books referred to earlier. Further modeling elforts are discussed by Denn.(66) However, it is fair to say that no totally acceptable rheological model has so far been found to quantitatively explain viscoelastic fiber-spinning results. The question of rheological constitutive equations is examined briefly in Section 7. 

The processes we have considered thus far - extrusion, wire coating, and injection and compression molding - are dominated by shear between confined surfaces. By contrast, in fiber and film formation the melt is stretched without confining surfaces. It is still possible to gain considerable insight from very elementary flow and heat transfer models, but we must first parallel Section 2.2 and develop some basic concepts of extensional flow. The remainder of the chapter is then devoted to an analysis of fiber formation by melt spinning. 

The book begins with introductory material and a brief review of fundamentals, after which the first part focuses on analytical treatments of basic polymer processes extrusion, mold filling, fiber spinning, and so forth. The thin gap (lubrication) and thin filament approximations are employed, and all analyses in this part are for inelastic liquids. An introduction to finite element calculation follows, where full numerical solutions are compared to analytical results. Polymer rheology is then introduced, with an emphasis on relatively simple viscoelastic models that have been used with some success to model processing operations. Applications in which melt viscoelasticity is important are then revisited, followed by a chapter on stability and sensitivity that focuses on melt spinning and a chapter on wall slip and extrusion... 

Swierenga and co-workers [79,80] in two articles described in detail their development of the calibration model used for PET measurements. Van Wijk et al. [72] summarized from their work that Raman spectroscopy can be used for determining the dye uptake or measuring one or more structural parameters or mechanical properties of polymeric fibers. Based on the results of their work, the authors stated that Raman spectroscopy was useful for studying melt-spinning thermoplastics, such as polyester, polyamide, polyolefins, and alternating copolymers of carbon monoxide and olefins so-called polyketones and, in addition, for polymers which are spun from solution such as cellulose, aromatic polyamides, polyketones, aromatic polyesters, and polyolefins. 

Figure 4.39 Schematic representation of the single filament melt-spinning model [107, 108].

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