Morphology and mechanical properties of ultrahigh molecular weight polypropylene prepared by gelation/crystallization at various temperatures

Ogita, Tetsuya; Kawahara, Yoshihisa; Soga, Yukihiro; Matsuo, Masaru

doi:10.1007/bf00657727

Cited by 14 publications

(11 citation statements)

References 11 publications

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“…The second disentangled polymer in which the mechanical properties were studied was polypropylene. For UHMWPP film from the gel solution, drawn at room temperature, it was possible to obtain a deformation ratio of 60 . The dried gel‐cast sheets of UHMWPP were examined in a two‐step drawing by Ikeda et al In the first step the sheets were drawn to a ratio of 10, in the second step strips were cut from them and were drawn to break.…”

Section: Properties Of Polymers With Limited Density Of Entanglementsmentioning

confidence: 99%

The Entanglements of Macromolecules and Their Influence on the Properties of Polymers

Pawlak

2019

Macro Chemistry & Physics

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Macromolecules form entanglements, the presence of which determines many of the polymer's properties; in solution, melt, and solid state. In this review, how the properties of polymers (rheological, thermal, and mechanical), depend on the concentration of the entanglements, is discussed. Although a typical polymer is characterized by the equilibrium density of entanglements, there are methods that can be applied for the reduction of this density. The methods used most often include dissolving a polymer and rapid freezing, crystallization during polymerization, and crystallization from a cooled dilute solution. The properties of disentangled polymers are significantly different from the properties of fully entangled polymers. These properties are discussed in relation to their dependence on the density of the entanglements. The disentangled material can be re‐entangled by the annealing of the polymer; however, reaching the equilibrium density of the entanglements is usually a slow process. It means that a polymer may be processed without losing its disentanglements. The properties of the re‐entangled polymer are usually close to the properties of the initial polymer.

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Section: Properties Of Polymers With Limited Density Of Entanglementsmentioning

confidence: 99%

The Entanglements of Macromolecules and Their Influence on the Properties of Polymers

Pawlak

2019

Macro Chemistry & Physics

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“…Polymers with lowered density of entanglements can be drawn to very large deformation ratio. Three different approaches were proposed for limitation of the entanglements of macromolecules in amorphous phase of solid polymer: (a) crystallization under pressure with formation of extended chains crystals [available only for certain polymers, e.g., high density polyethylene (HDPE), polyamides], (b) crystallization during polymerization [e.g., poly(tetrafluoroethylene) (PTFE), polyethylene (PE))], (c) crystallization from dilute solution (polyolefins) …”

Section: Introductionmentioning

confidence: 99%

Deformation of disentangled polypropylene crystalline grains into nanofibers

Krajenta

Pawlak

Gałęski

2016

J Polym Sci B Polym Phys

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It was shown that a solid‐state deformation of polypropylene (PP) being in the form of partially disentangled powder is possible by blending with another molten polymer. During mixing of disentangled polypropylene powder with polystyrene at the temperature below melting of polypropylene crystals the shear forces deform powder grains into nanofibers. All disentangled powder particles larger than 0.7 µm underwent deformation into nanofibers having the mean thickness between 100 and 200 nm. Polypropylene nanofibers got entangled during blending and form a network within polystyrene matrix, reinforcing it. Network of entangled nanofibers can be further deformed with pronounced strain hardening and strength reaching 70 MPa at 135 °C. Blending resulted in generation of PP nanofibers and formation of PP nanofibers entangled network, thus formation of “all‐polymer nanocomposites” in one step compounding. The crucial feature for ultra‐deformation of PP grains by shearing during mixing is disentanglement of macromolecules. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1983–1994

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“…The entanglement concept has been verified by the successful development of polymer gel technol ogy [2][3][4], which has formed the basis for the indus trial production of high strength fibers. The tendency to improve the mechanical properties of fibers obtained from gels almost always consists in the search for optimum technology and the creation of concen tration junctions of a macromolecular network that provide the effective formation of a regular structure during orientational drawing [5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Structure of the crystalline phase in gelled polyethylene and its effect on the orientational ability of gel fibers

et al. 2012

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The crystalline phase of gelled ultrahigh molecular weight polyethylene derived from reactor powders with different synthetic prehistories is studied by means of low frequency Raman spectroscopy and small angle X ray scattering. The results obtained suggest that the gels contain folded crystallites 3-6 nm in size that, in some samples, form stacks of two or more units bound by common straightened segments of mac romolecules (double folds). The gels are used to prepare highly oriented polyfilament fibers, and the strengths and Young moduli of the fibers are estimated. The gels containing stacks of crystallites demonstrate better ability to form high strength fibers during hot drawing than the gels containing individual crystallites. The effect of the strength of junctions in the polymer spatial network of the gels on the attainment of optimum mechanical properties of the drawn fibers is discussed.

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Morphology and mechanical properties of ultrahigh molecular weight polypropylene prepared by gelation/crystallization at various temperatures

Cited by 14 publications

References 11 publications

The Entanglements of Macromolecules and Their Influence on the Properties of Polymers

The Entanglements of Macromolecules and Their Influence on the Properties of Polymers

Deformation of disentangled polypropylene crystalline grains into nanofibers

Structure of the crystalline phase in gelled polyethylene and its effect on the orientational ability of gel fibers

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