Structure Morphology Flow of Polymer

Su, Wen

doi:10.1007/978-3-642-38730-2_3

Cited by 8 publications

(4 citation statements)

References 10 publications

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“…The effect of tacticity on polymer chain miscibility is also reflected in the different microphases in which block copolymers usually self-organize. Different tacticities can lead to the formation of different microphases such as lamellae, cylindrical, hexagonal, etc., out of copolymers of the same composition. − Therefore, tacticity of the blocks is a very important design parameter in block copolymer applications, such as directed self-assembly (DSA) lithography. − …”

Section: Introductionmentioning

confidence: 99%

“…Our main target is to identify the microscopic mechanisms through which the chirality of polymer chains affects their stiffness. A very promising candidate in this study was polypropylene (PP) homopolymer due to its simple chemical constitution and the plethora of different conformations it adopts (i.e., 3 1 helical conformation with s(3/1)1 symmetry for isotactic, 2 1 helical conformation with s(2/1)2 symmetry for syndiotactic, and random coil conformation for atactic). ,,− The stiffness and the conformations of single unperturbed PP chains and their dependence on tacticity at various temperatures have been studied in many works through RIS calculations, − and the results have been compared against the corresponding experimental estimates through SANS , and/or intrinsic viscosity measurements . Unfortunately, none of these works provide a microscopic explanation of how tacticity affects stiffness and what are the mechanisms in action.…”

Section: Introductionmentioning

confidence: 99%

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Tacticity Effect on the Conformational Properties of Polypropylene and Poly(ethylene–propylene) Copolymers

et al. 2018

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Tacticity is one of the most important features of stereoregular polymers, with significant impact on morphology and on a variety of properties such as conformational, thermal, rheological, mechanical, etc. In this work we focus on tacticity effects on the conformations and more specifically on the unperturbed dimensions of single polypropylene (PP) homopolymer and both block and random poly(ethylene−propylene) copolymer chains. The equilibration of all chains is achieved by applying the single-chain Monte Carlo algorithm of Tzounis et al. [Macromolecules 2017, 50, 4575−4587]. In agreement with past studies, we find that tacticity has a significant effect on the stiffness of PP homopolymer. The characteristic ratio exhibits a nonmonotonic dependence on the fraction of meso dyads along the PP chains, which results from two competing mechanisms, revealed by analysis of the torsional states of the PP chain backbones. A simple theoretical model is developed to describe the dependence of the stiffness of poly(ethylene-block-propylene) copolymer on its propylene content and on the tacticity of its PP block. Finally, the effect of both tacticity and propylene content on the stiffness of poly(ethylene-randompropylene) chains, used to model ethylene−propylene monomer (EPM) materials, is found to be in very good qualitative agreement with available rotational isomeric state (RIS) model predictions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tacticity Effect on the Conformational Properties of Polypropylene and Poly(ethylene–propylene) Copolymers

et al. 2018

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“…As the shear rate goes up, disruption in the entanglement starts taking place. However, the polymer tries to retain its entanglement until the shear rate is high enough to disrupt it significantly 57 . After the entanglement is disrupted, the molecules start to be aligned and viscosity reduces.…”

Section: Resultsmentioning

confidence: 99%

Morphology, mechanical, and physical properties of wet‐spun cellulose acetate fiber in different solvent‐coagulant systems and in‐situ crosslinked environment

Swapnil

Datta

Mahmud

et al. 2020

J of Applied Polymer Sci

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Wet spinning is a popular fiber manufacturing process where the effects of solvent and coagulant on the wet‐spun fiber are significant. In this study, we have explored the effect of solvent‐coagulant interaction and in‐situ crosslinking on the wet‐spun cellulose acetate (CA) fiber. Investigation on 12 different solvent‐coagulant systems revealed that variation in the systems resulted in significant variance in morphology and mechanical property of the fiber. Remarkable increase in mechanical property was observed after in‐situ crosslinking with citric acid and polyethylene glycol (PEG). Inclusion of sodium hypophosphite (NaH2PO2) as catalyst further increased tensile modulus (~407%) and crystallinity index (~46%) compared to CA fiber crosslinked with only citric acid. It was established that fiber from CA‐DMSO solution crosslinked with 10% citric acid and 10% PEG extruded in ethanol showed the highest tensile modulus (~30 MPa). This in‐depth study found an appropriate combination of solvent‐coagulant for forming stable CA fiber, with the addition of crosslinkers and catalyst further increasing the strength and usability of the fiber.

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“…Furthermore, the branching degree is a critical variable in rheology. In specific shear rate, the higher the branching degree for a given polymer, the lower its hydrodynamic volume and entanglement degree, and thus the lower the generated thickening effect due to lack of intermolecular secondary bond [ 26 ]. The low branching degree as reported in the molecular structure of the P. flavescens crude EPS extract is a perfect illustration of this argument.…”

Section: Resultsmentioning

confidence: 99%

Structure and Foaming Properties of Viscous Exopolysaccharides from a Wild Grape-Associated Basidiomycetous Yeast Papiliotrema flavescens Formerly Known as Cryptococcus flavescens

Oluwa

2020

J. Microbiol. Biotechnol.

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Exopolysaccharide produced by the yeast Papiliotrema flavescens , isolated from wine grape berries of Champagne vineyard, was investigated for both chemical and functional characterization. SECMALLS and colorimetric assay analyses showed that the EPS is a high M W heteropolymer (2.37 × 10 6 g/mol) majorily consisting of mannose, glucose, xylose and glucuronic acid as monosaccharide constituents, with two substituents (sulphate and phosphate groups), and a minor protein moiety. Structural enchainment of these carbohydrates based on methylation, GC-MS and NMR analyses revealed a linear main backbone built up of α-(1 →3)-D-mannopyranosyl residues on which are branched side chains consisting of a single β-D-glucopyranosyluronic acid residue and β-(1 →2)- xylopyranoses (2-5 residues). Suggestion of some xylopyranose side chains containing a mannose residue at the nonreducing terminal end was also proposed. This is first report on EPSs from the grape P. flavescens yeast with such structural characteristics. Furthermore, investigations for valuating the application performance of these EPS in relation with their structural features were carried out in 8% alcohol experiment solutions. Very exceptional viscosifying and foaming properties were reported by comparison with commercial biopolymers such as Arabic, gellan and xanthan gums. The intrinsic properties of the natural biopolymer from this wild grape-associated P. flavescens yeast make it a potential candidate for use in various biotechnology applications.

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Structure Morphology Flow of Polymer

Cited by 8 publications

References 10 publications

Tacticity Effect on the Conformational Properties of Polypropylene and Poly(ethylene–propylene) Copolymers

Tacticity Effect on the Conformational Properties of Polypropylene and Poly(ethylene–propylene) Copolymers

Morphology, mechanical, and physical properties of wet‐spun cellulose acetate fiber in different solvent‐coagulant systems and in‐situ crosslinked environment

Structure and Foaming Properties of Viscous Exopolysaccharides from a Wild Grape-Associated Basidiomycetous Yeast Papiliotrema flavescens Formerly Known as Cryptococcus flavescens

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