Flow instability for binary blends of linear polyethylene and long-chain branched polyethylene

Mieda, Naoya; Yamaguchi, Masayuki

doi:10.1016/j.jnnfm.2010.11.011

Cited by 22 publications

(18 citation statements)

References 48 publications

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“…Conversely, sharkskin failure is detected before gross melt fracture for LLDPE when the applied shear stress is above the critical value. Mieda et al examined the flow instability of binary blends that were composed of LLDPE and LDPE. The blends that contained LLDPE with a high shear viscosity showed a number of anomalous rheological responses: (i) Their strain‐hardening behavior in the elongational viscosity is more pronounced than that for LDPE.…”

Section: Introductionmentioning

confidence: 99%

Impact of Mixing Method on Rheological Instability for Binary Mixture of Linear Low‐Density Polyethylene

et al. 2016

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The impact of different mixing methods on flow instability in capillary extrusion was examined using binary mixtures of linear low-density polyethylene with different molecular weights. The polymers were blended using a single-screw extruder, a twin-screw extruder, and a twin-screw mixer. The onset of flow instability changed depending on the mixing method used, even though their linear viscoelastic properties were almost identical. The mixtures that were subjected to mixing methods with weak mixing capability exhibit sharkskin failure even at low shear stress and low values of the maximum draw ratio without rupture in the molten state. The results suggested that mechanically weak points were present, which led to cohesive failure at the strand surface following abrupt stretching at the die exit (i.e., sharkskin failure). In contrast, the mixture that was subjected to thorough mixing exhibited smooth surface at high shear stress and a large maximum draw ratio.

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Section: Introductionmentioning

confidence: 99%

Impact of Mixing Method on Rheological Instability for Binary Mixture of Linear Low‐Density Polyethylene

et al. 2016

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“…13,14 For the so-called "Meissner-type" rheometer, a sample is clamped between two pairs of rollers, moving at a constant velocity, and floated horizontally in a silicon oil bath or by blowing nitrogen gas. [23][24][25] Furthermore, the measurement can be performed even for a low viscous melt. [15][16][17][18][19][20] Later, Sentmanat fabricated a dual wind-up extensional rheometer, composed of two counter-rotating drums, in which the ends of a sample are allowed to be stretched.…”

Section: Introductionmentioning

confidence: 99%

Effect of Die Geometry on Drawdown Force of Polypropylene at Capillary Extrusion

et al. 2014

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Drawdown force, defined as the force needed to stretch a polymer melt uniaxially at capillary extrusion, is investigated using isotactic polypropylene. In this study, we focus on the effect of die geometry on the drawdown force. As similar to the swell ratio, which decreases with increasing die length, the drawdown force is found to increase with the die length. A prolonged residence time in a long die leads to the marked orientation. Consequently, crystallization occurs rapidly after passing through a long die, which is confirmed by wide-angle X-ray measurements. Moreover, the rapid crystallization by the addition of a nucleating agent also enhances the drawdown force. C 2014 Wiley Periodicals, Inc. Adv Polym Technol 2015, 34, 21477; View this article online at wileyonlinelibrary.com.

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“…This equation provides the information on processing failures due to the pronounced melt elasticity (high Deborah number) including the shark‐skin failure . When a polymer melt has narrow molecular weight distribution, that is, small f , Deborah number becomes large at a constant shear stress.…”

Section: Resultsmentioning

confidence: 99%

Viscoelastic properties and extrusion processability of poly(vinyl butyral)

Arayachukiat

Siriprumpoonthum

Nobukawa

et al. 2014

J of Applied Polymer Sci

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Rheological properties and flow instability at capillary extrusion of a random terpolymer composed of vinyl butyral, vinyl alcohol, and vinyl acetate, that is denoted as PVB in this article, are studied. It is found that the rubbery plateau modulus G 0 N is 1.3 MPa at 100 C from the oscillatory shear modulus. Furthermore, the average molecular weight between entanglement couplings M e is found to be 2670. Because of the relatively high value of G 0 N , it shows rubbery region in the wide temperature range (90 C-180 C). At the capillary extrusion, the surface instability (shark-skin failure) appears prior to volumetric melt fracture. The onset stress of the shark-skin failure, ca. 0.18 MPa, is similar to that of polyethylene, although PVB used in this study has narrow molecular weight distribution. Moreover, the apparent slippage is not detected, presumably due to good adhesion to the die wall. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40337.

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Flow instability for binary blends of linear polyethylene and long-chain branched polyethylene

Cited by 22 publications

References 48 publications

Impact of Mixing Method on Rheological Instability for Binary Mixture of Linear Low‐Density Polyethylene

Impact of Mixing Method on Rheological Instability for Binary Mixture of Linear Low‐Density Polyethylene

Effect of Die Geometry on Drawdown Force of Polypropylene at Capillary Extrusion

Viscoelastic properties and extrusion processability of poly(vinyl butyral)

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