Extrudate swell of immiscible polymer blends

as the shear stress increases (i.e., as the extrusion rate increases), the d lD ratio also increases, which is consistent with the view that the drop recoil, upon exiting the die, is attributable to extrudate swell. The higher the extrusion rate, the greater will be the extent of drop deformation inside the die. Second, the d lD ratio goes through a maximum at a blend composition of 20 wt % HOPE, suggesting that the extent of drop deformation is the largest at that particular blend composition. 

Lyngaae-j0rgensen et al., Polymer Alloys III, Klempner D, Frisch KC (eds), p 105. Copyright 1983, with permission from Springer.) 

namely, nvshvuuK 1 on the left side of an arrow and 7ps/ pmma 1 on the right side of an arrow. It has been reported that in the 25/75 PS/PMMA blend the minor component PS forms drops with sizes of 0.2-0.6 p,m dispersed in the continuous phase of PMMA, and that in the 50/50 PS/PMMA blend the PS forms drops with sizes of 0.4-3.5 p,m dispersed in the continuous phase of PMMA (Lyngaae-Jprgensen et al. 1983). 

It should be pointed out that the physical origin of the increasing trend of t/j/D ratio with increasing a observed for the 25/75 and 50/50 PS/PMMA blends 

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