Polystyrene extrudate swell

Figure 7.56 Extrudate swelling in polystyrene melts for ( ) broad molecular weight distribution and (O, a) narrow molecular weight distribution samples. From Z. Tadmor and C. G. Gogos, Principles of Polymer Processing, Copyright 1979 by John Wiley Sons, Inc. This material is used by permission of John Wiley Sons, Inc.

Combine your results to obtain a value for the shear stress at the capillary wall, and use that value to estimate the extrudate swell, D/Dq for polystyrene using Figure 7.56. What effect does molecular weight have on die swell at these shear levels ... 

Fig. 12.13 Extrudate swelling data for polystyrene melts , broad molecular weight sample O, , A, narrow distribution sample data at various temperatures. [Reprinted by permission from W. W. Graessley, S. D. Glasscock, and R. L. Crawley, Die Swell in Molten Polymers, Trans. Soc. Rheol., 14, 519 (1970).]...

FIG. 15.34 Extrudate swell ratio and viscosity, both as functions of shear rate, for a polystyrene melt of Mw = 2.2 x 105 and M /Mn — 3.1. From Greassley et al. (1970). Courtesy Society of Rheology. 

FIGURE 7.16 Capillary extrudate swell versus wall shear stress for a commercial polystyrene at three temperatures (o) 160 °C, (A) 180 °C, ( ) 200 °C. (Data from Graessley et al., 1970.)... 

Loose fill for packaging is produced by extruding and chopping polystyrene into various shapes, swelling with pentane, and steaming to expand them into peanuts. ... 

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