Modifying the rheological properties of polypropylene under elongational flow by adding polyethylene

Fujii, Yoko; Nishikawa, Riho; Phulkerd, Panitha; Yamaguchi, Masayuki

doi:10.1122/1.5049378

Cited by 25 publications

(9 citation statements)

References 53 publications

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“…The viscoelastic properties of PP‐H and PE‐L were reported previously. [ 27,28,36 ] For PS samples, the number‐ ( M n ) and weight‐average ( M w ) molecular weights, as evaluated by gel permeation chromatography (HLC‐8020, Tosoh, Japan), were M n = 99,000 and M w = 240,000 for PS‐H, and M n = 3300 and M w = 4000 for PS‐L. The viscoelastic properties for PS‐H and PS‐L were summarized in preceding papers.…”

Section: Methodsmentioning

confidence: 99%

“…This is currently one of the main purposes of employing polymer blends. Their purposes can roughly be classified into two categories: (1) to provide strain hardening in the transient elongational viscosity [ 23‐31 ] and (2) to decrease the shear viscosity to enhance flowability. In the latter case, adding low‐molecular‐weight compounds has been employed as a conventional method, which largely reduces the shear viscosity in the low shear rate region.…”

Section: Introductionmentioning

confidence: 99%

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Viscosity decrease by interfacial slippage between immiscible polymers

Moonprasith

Nasri

Saari

et al. 2021

Polymer Engineering & Sci

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The rheological behavior under pressure‐driven shear flow was studied using binary blends with a sea‐island structure. The addition of a low‐viscosity dispersion having a high interfacial tension with the continuous phase greatly reduces the shear viscosity, for example, the addition of atactic polystyrene (PS) with a low viscosity to isotactic polypropylene (PP) and the addition of PP with a low viscosity to PS. The interfacial slippage occurs because of the poor adhesive strength with the enlarged interfacial area and is responsible for the viscosity decrease. When the dispersion has a similar viscosity to the continuous phase, the viscosity decrease is barely detected. This is because the deformation of dispersed droplets is restricted, which creates a small interfacial area. The interfacial tension between the continuous and dispersed phases plays a crucial role on the shear viscosity. In the case of PP, the addition of linear low‐density polyethylene with a relatively low interfacial tension to PP has almost no impact on the shear viscosity. This is despite the polyethylene having a low viscosity.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Viscosity decrease by interfacial slippage between immiscible polymers

Moonprasith

Nasri

Saari

et al. 2021

Polymer Engineering & Sci

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“…Various studies have shown that the high aspect ratio fibrils change the rheological behavior of the matrix. [ 75, 87‐89 ] The polymer fibrils of a high aspect ratio form a physical network structure inside the polymer matrix and endow it with strain hardening behavior. Furthermore, the fibrils enhance the crystallization rate and increase the number of crystals of the matrix.…”

Section: Introductionmentioning

confidence: 99%

Recent progress in micro‐/nano‐fibrillar reinforced polymeric composite foams

Zhao

Mark

Kim

et al. 2021

Polymer Engineering & Sci

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Manufacture of thermoplastic foams with a fine cellular structure (a higher expansion ratio, a higher cell density, and smaller cell sizes) is challenging work due to the weak viscoelastic behavior and the unsuitable crystallization behavior of common thermoplastic materials. In this work, a novel method of making microcellular foams with micro‐/nano‐fibrillar reinforced polymeric composites (M/NFC) is introduced, which shows various advantages compared to conventional foams. The M/NFC foams have improved cellular structures, excellent mechanical properties, and enhanced thermal insulation properties, which make them popular candidates for structural applications and insulative products. Various methods to manufacture of M/NFC foam are summarized. To understand the fundamental mechanisms of the foaming enhancement by incorporating micro‐/nano‐size fibrils, the rheological and crystallization behavior of the M/NFC are analyzed. It is shown that the micro‐/nano‐fibrils can strengthen the melt strength, induce faster crystallization, and increase the number of crystals. Due to the improvement of the cell morphology and the stiffness of the cell walls, the reinforced foams have superior mechanical properties. A hierarchically porous structure in high expansion ratio reinforced foams has also been developed. It is believed that the nano‐size holes in the cell walls can further reduce the thermal conductivity of the foams.

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“…The addition of rubbery materials to enhance the mechanical toughness is another major target for polymer blends. [1][2][3][4] Although various blend techniques have been proposed recently to improve the processability, [5][6][7][8][9][10][11] there is still a strong need to reduce the shear viscosity, especially for injection molding of engineering plastics.…”

Section: Introductionmentioning

confidence: 99%

Effect of morphology on shear viscosity for binary blends of polycarbonate and polystyrene

Tanaka

Sako

Hiraoka

et al. 2020

J of Applied Polymer Sci

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The structure and rheological properties of binary blends of polycarbonate (PC) and polystyrene (PS) were investigated using various PS samples with different molecular weights, namely PS1k (Mw = 1,000), PS53k (Mw = 53,000), and PS240k (Mw = 240,000). The blends with PS53k and PS240k show phase‐separated structures, whereas the blend with PS1k is miscible. The shear viscosity decreases greatly on addition of PS53k and PS240k, especially at high shear rates, which would be a great advantage at processing operations. Because the nonlinear response occurs in the small strain region for multilayered films of PC and PS240k, the origin of the significant viscosity drop for the phase‐separated system is interfacial slippage at the phase boundary.

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Modifying the rheological properties of polypropylene under elongational flow by adding polyethylene

Cited by 25 publications

References 53 publications

Viscosity decrease by interfacial slippage between immiscible polymers

Viscosity decrease by interfacial slippage between immiscible polymers

Recent progress in micro‐/nano‐fibrillar reinforced polymeric composite foams

Effect of morphology on shear viscosity for binary blends of polycarbonate and polystyrene

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