Crystallization Behavior of Syndiotactic Poly(propylene) Freeze-Dried from Toluene at Very Dilute Concentration

Sun, Qizhen; Fu, Qiang; Xue, Gi; Chen, Wei

doi:10.1002/1521-3927(20011001)22:14<1182::aid-marc1182>3.0.co;2-4

Cited by 30 publications

(27 citation statements)

References 14 publications

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“…with decreasing freeze-drying solution concentration. The result has implications for the interpretation of the T g depression of freeze-dried materials [2][3][4][5][6][7][8][9][10][11][12][13][14], as well as for the behavior of other properties of materials freeze-dried from dilute solution [7,[45][46][47][48], since previous experimental protocols involve removal of solvent by freeze-drying and/or annealing under vacuum at low temperatures. The results also have practical implications for the general use of freezedrying as a materials preparation technique.…”

Section: Discussionmentioning

confidence: 99%

Polystyrene freeze-dried from dilute solution: Tg depression and residual solvent effects

Zheng

Simon

2006

Polymer

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Section: Discussionmentioning

confidence: 99%

Polystyrene freeze-dried from dilute solution: Tg depression and residual solvent effects

Zheng

Simon

2006

Polymer

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“…The disentangled polymers after solidification can be used for studies of crystallization from liquid state (melt, solution) or crystallization in the solid state (i.e., cold crystallization). The crystallization from disentangled melt was examined for iPP, sPP, PLA, iPS, PEO, and UHMWPE . Cold crystallization was examined for PC, PET, PEO, and iPS .…”

Section: Properties Of Polymers With Limited Density Of Entanglementsmentioning

confidence: 99%

“…FTIR and WAXS observations of freeze‐dried syndiotactic polypropylene showed that the sample obtained from the lowest polymer concentration in solution had trans‐planar conformation (zigzag packing) mixed with helix‐chain conformation . Samples from higher concentrations represented helical conformation.…”

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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“…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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Crystallization Behavior of Syndiotactic Poly(propylene) Freeze-Dried from Toluene at Very Dilute Concentration

Cited by 30 publications

References 14 publications

Polystyrene freeze-dried from dilute solution: Tg depression and residual solvent effects

Polystyrene freeze-dried from dilute solution: Tg depression and residual solvent effects

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

Deformation of disentangled polypropylene crystalline grains into nanofibers

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