Fiber melt extrusion: Deviations from steady‐state behavior in the spin line

Freeman, Howard I.; Coplan, Myron J.

doi:10.1002/app.1964.070080529

Cited by 27 publications

(10 citation statements)

References 6 publications

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“…(5) and (6). Broadening the molecular weight distribution decreases G (increasing steady-state compliance) and increases a.…”

Section: Comparison To Theories Of Melt Spinningmentioning

confidence: 95%

“…(5), (6), and (9) but which neglects eq. (9b), we obtain The above conclusions may be used to explain some of the perplexing results of Acierno et a1.l and Han and Lamonte.2 They find that xsp is a decreasing function of elongation rate for PS melts which give an increasing x,35-37 while the latter authors find xsp to be a constant in one case for LDPE which has an increasing x.37-3g The xsp character of LDPE and PS (as well as HDPE) depends on the a parameters listed in Table 111.…”

Section: Comparison To Theories Of Melt Spinningmentioning

confidence: 98%

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Experimental investigations of the influence of molecular weight distribution on melt spinning and extrudate swell characteristics of polypropylene

Minoshima¹,

White²,

Spruiell³

1980

J of Applied Polymer Sci

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SynopsisAn experimental study of the influence of molecular weight distribution on the melt spinning and extrudate swell of a series of polypropylenes of varying molecular weight and distribution is reported. Emphasis is given to effects of variations of molecular weight distribution. Narrowing the molecular distribution increases the slope of the elongational viscosity-elongation rate curve, stabilizes the spinline relative to both random disturbances and draw resonance, and decreases both instantaneous and delayed extrudate swell. These results are interpreted in terms of viscoelastic fluid mechanics and earlier experimental studies by the authors of the influence of molecular weight distribution on rheological properties. The influences of these rheological factors on spinline structure development is discussed.

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“…(5) and (6). Broadening the molecular weight distribution decreases G (increasing steady-state compliance) and increases a.…”

Section: Comparison To Theories Of Melt Spinningmentioning

confidence: 95%

Section: Comparison To Theories Of Melt Spinningmentioning

confidence: 98%

Experimental investigations of the influence of molecular weight distribution on melt spinning and extrudate swell characteristics of polypropylene

Minoshima¹,

White²,

Spruiell³

1980

J of Applied Polymer Sci

View full text Add to dashboard Cite

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“…Miller (1963), Freeman and Coplan (1964), Bergonzoni and DiCresce (1966), Lamb (1967), Kase (1974), Weinberger and coworkers (1976), Matsumoto and Bogue (1978), White and Ide (1978), Chang and Denn (1980), Ghijsels and Ente (1980), Demay and Agassant (1985), etc.). In these studies, a variety of polymers have been tested to show draw resonance.…”

Section: Introductionmentioning

confidence: 95%

A Correlation of the Onset of Draw Resonance Spinline Instability

Lee¹

1987

Chemical Engineering Communications

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Draw-resonance instability observed in fiber spinning is experimentally examined with an isothermal monofilament spinning setup. Two polypropylene resins are used in this study. An apparent spinline elongation rate is obtained and found to be a key parameter influencing the onset of draw resonance. From dimensional analysis, the critical draw-down ratio is seen to depend on several dimensionless groups. An important one can be expressed by the ratio between the spinline elongation rate (T) and the spinneret extrusion shear rate ( y ) .A dimensionless cr.itical stability contour is constructed in a plot of the critical draw-down ratio versus the ratio of (Tly). This stability contour provides a guideline for stable spinning conditions based on rheologically significant parameters. The validity of this stability contour is confirmed by the critical spinline stability data of the two different polypropylene resins operated at conditions with the same rheological properties.

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“…Chen et a1.23 suggest that the tensile stress S,, ( 2 ) in a molten threadline be estimated by S,,(z) = SZZ(0)e-'/AO + m(t -t')(C;; -C;') dt' history fro'm the die…”

Section: Critique Of Theoretical Analyses Of Draw Resonancementioning

confidence: 99%

Studies on melt spinning. VIII. The effects of molecular structure and cooling conditions on the severity of draw resonance

Han

Apte

1979

J of Applied Polymer Sci

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SynopsisThe effects of molecular structure and cooling conditions on the sever,ity of draw resonance was investigated by carrying out carefully controlled melt spinning experiments. For the study, two types of polymeric materials were used: one which exhibits viscoelastic behavior (high-density polyethylene, polypropylene, and polystyrene), and the other which exhibits almost Newtonian behavior (nylon-6 and poly(ethy1ene terephthalate)]. In order to investigate the effect of cooling on the severity of draw resonance, different methods of cooling the molten threadline were employed. In one set of experiments, isothermal chambers of various lengths (3,6, and 12 in.) were attached to the spinnerette face, so that the molten threadline, upon exiting from the spinnerette, began to cool in the ambient air only after it had passed through the isothermal chamber. This method of cooling is called "delayed cooling," providing both an isothermal region (inside the isothermal chamber) where only stretching occurs, and a nonisothermal region (outside the isothermal chamber) where both stretching and cooling occur simultaneously. In other experiments, the temperature profile of the molten threadline was controlled by adjusting the temperature of the heated chamber. This method of cooling provides a gradual drop of the threadline temperature, compared to the more sudden drop when spinning into a cold environment provided a t the spinnerette exit. The severity of draw resonance was recorded on movie film, and the thread tension was measured with a low-force load cell transducer and recorded on a chart recorder. The temperature of the threadline along the spin direction was measured using a fiber optical probe attached to a Vanzetti Infrared Thermal Monitoring System (Model TM-1). It was found that the severity of draw resonance depended on the molecular structure and the way the molten threadline was cooled. Of particular interest is the observation that, for the visctdastic materials investigated, ctwling destabilized the molten threadline outside the isothermal chamber. This gave rise to more severe resonant behavior, a t and above the critical draw-down ratio, in contradiction to the theoretical prediction by Fisher and Denn. It was observed, also, that the elasticity of the materials tended to destabilize the molten threadline (i.e., it increased the severity of draw resonance), again in contradiction to the theoretical prediction of Fisher and Denn. It is believed that morphological changes of polymers may play an important role in the occurrence of draw resonance when a melt threadline is stretched under cooling. Our study indicated that a good understanding of draw resonance of viscoelastic fluids requires more careful study than the classical hydrodynamic stability analysis reported by Fisher and Denn. They based their analysis on several convenient and yet unjustified assumptions, and solely on phenomenological considerations. We suggest that future theoretical analysis of draw resonance he carried out by considering a ...

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Fiber melt extrusion: Deviations from steady‐state behavior in the spin line

Cited by 27 publications

References 6 publications

Experimental investigations of the influence of molecular weight distribution on melt spinning and extrudate swell characteristics of polypropylene

Experimental investigations of the influence of molecular weight distribution on melt spinning and extrudate swell characteristics of polypropylene

A Correlation of the Onset of Draw Resonance Spinline Instability

Studies on melt spinning. VIII. The effects of molecular structure and cooling conditions on the severity of draw resonance

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