Sharkskin and cracking of polymer melt extrudates

Kissi, Nadia El; Piau, Jean‐Michel; Toussaint, Fabrice

doi:10.1016/s0377-0257(96)01507-8

Cited by 102 publications

(60 citation statements)

References 22 publications

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“…Recently, a theory that has gained some favour considers sharkskin to be caused by rupture of the outer layers of the extrudate as its velocity profile rearranges from a parabolic to a flat one at the die lip, i.e., as the extrudate exits the flow channel. This has been corroborated by a number of researchers [24][25][26][27][28]. Rutgers and Mackley [23], in particular, have compared the rupture stress derived from the Rheotens test with that present at the die lip wall at the onset of sharkskin and shown that they are of very similar magnitudes.…”

Section: Introductionmentioning

confidence: 63%

Time dependent effects on the rupture of molten linear polymers in extension

Barroso

Maia

2005

Journal of Non-Newtonian Fluid Mechanics

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Section: Introductionmentioning

confidence: 63%

Time dependent effects on the rupture of molten linear polymers in extension

Barroso

Maia

2005

Journal of Non-Newtonian Fluid Mechanics

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“…The first limiting factor on the production rate or processability during polymer processing is the onset of sharkskin or melt fracture. 15,16 The effect of long-chain branches of PP on the onset of melt fracture was observed from the extrudate appearance.…”

Section: Introductionmentioning

confidence: 99%

Rheological properties of polypropylene modified by high‐intensity ultrasonic waves

Kim

Nam²,

Lee³

et al. 2005

J of Applied Polymer Sci

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ABSTRACT:A new method using high-intensity ultrasonic waves, instead of peroxide-aided reactive extrusion, was applied to modify a linear polypropylene into a branched structure. The ultrasonic waves induced chain scission and created reactive macromolecules of polypropylene successfully in the melt state without any peroxide. To enhance and control the recombination reaction during sonication, a multifunctional agent and an antioxidant were used. The rheological property measurements clearly confirmed that the modified polypropylene had a nonlinear branched structure. It showed shear-thinning behaviors in its viscosities at low frequencies, high elastic behaviors in Cole-Cole plots, and a high rheological polydispersity index in comparison with a linear polypropylene. The degradation or recombination of polypropylene was adequately controlled by an antioxidant, which stabilized the structure during sonication. Also, the use of an antioxidant was quite effective in improving the extrusion processability by delaying the instability of the extrudate to a higher shear rate.

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“…[2][3][4][5][6][7][8][9][10]. The use of fluorinated dies [8,11,12] could significantly delay the appearance of such defects. Also the use of processing additives [13][14][15][16][17] may substantially postpone their onset.…”

Section: Introductionmentioning

confidence: 99%