Rheological properties of emulsions formed by polymer solutions and modified by nanoparticles

Ilyin, Sergey O.; Куличихин, В. Г.; Malkin, A. Ya.

doi:10.1007/s00396-015-3543-6

Cited by 17 publications

(6 citation statements)

References 42 publications

(54 reference statements)

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“…Blends of these polymers show similar viscoelasticity and intermediate moduli values, meaning no structuring of the dispersed droplets since the storage modulus would be almost independent of angular frequency otherwise, at least at low frequencies. 54,55 In addition, the low-frequency shoulder of the storage module, previously observed for some polymer blends and associated with the elasticity of the interfacial boundary, 56−61 is missing. The interfacial elasticity manifests itself when the elastic relaxation times of the matrix and droplet fluids are much shorter than the relaxation time of the droplets.…”

Section: ■ Materials and Methodsmentioning

confidence: 96%

Rheology and Miscibility of Linear/Hyperbranched Polydimethylsiloxane Blends and an Abnormal Decrease in Their Viscosity

Ilyin,

Kulichikhin

2023

Macromolecules

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Linear polymers with the same monomer units and different molecular weights form miscible blends considered to be single polymers, but the situation changes if one is hyperbranched. Hyperbranched macromolecules can significantly change the rheology of a linear polymer due to a different flow mechanism and can even lead to the formation of immiscible or partially miscible blends with unusual mechanical properties due to the emulsion state and low droplet–matrix interfacial tension. Blends of hyperbranched polydimethylsiloxane (silicone MT resin, H-PDMS) with similar linear polymers (L-PDMS) of different molecular weights in a concentration range from 20 to 80% have been studied in this work. Laser interferometry of the diffusion zone between H-PDMS and L-PDMS showed their limited miscibility that is improving with decreasing molecular weight of the linear polymer, leading to a decrease in the upper critical solution temperature. The solubility of H-PDMS in L-PDMS is much higher than that of L-PDMS in H-PDMS (20–50% versus 1–2% at 25 °C, depending on the molecular weight of L-PDMS), and H-PDMS emulsifies in L-PDMS but not vice versa. As a result, the partially miscible blends are emulsions of almost pure H-PDMS in a saturated H-PDMS/L-PDMS solution, even at an H-PDMS concentration as high as 80%. The thermorheological behavior of blends was described using an averaged combination of the Arrhenius and Williams–Landel–Ferry equations, allowing for overcoming the large difference in the glass transition temperatures of hyperbranched and linear macromolecules. The viscosity of blends with a higher-molecular-weight L-PDMS has a positive deviation from the log-additivity rule due to macromolecular entanglements, while a decrease in the molecular weight of L-PDMS causes an abnormal drop in viscosities below those of pure polymers. The anomalous decrease in viscosity appears only in a specific temperature range and is explained by mixing a polymer with a high glass transition temperature and high flow activation energy (H-PDMS) with one having lower values of these characteristics (L-PDMS).

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Section: ■ Materials and Methodsmentioning

confidence: 96%

Rheology and Miscibility of Linear/Hyperbranched Polydimethylsiloxane Blends and an Abnormal Decrease in Their Viscosity

Ilyin,

Kulichikhin

2023

Macromolecules

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“…At 20% concentrations of oils, the yield stress appears again, probably due to the formation of a new structure of interacting oil droplets [78][79][80][81]. In addition, one can observe a significant decrease in effective viscosity at high shear stresses, which may be due to the wall slip of the blends on the measuring surface of the rheometer units [82][83][84][85]. A more substantial wall slip (expressed as a more pronounced drop in effective viscosity) occurs with coconut oil, which is in the liquid state at the test temperature.…”

Section: Rheology Of Uncured Blendsmentioning

confidence: 99%

Self-Lubricating and Shape-Stable Phase-Change Materials Based on Epoxy Resin and Vegetable Oils

Ilyina,

Gorbunova,

Makarova

et al. 2023

Polymers

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Palm or coconut oil is capable of dissolving in a mixture of bisphenol A-based epoxy resin and a high-temperature hardener (4,4′-diaminodiphenyl sulfone) when heated and then forms a dispersed phase as a result of cross-linking and molecular weight growth of the epoxy medium. Achieving the temporary miscibility between the curing epoxy matrix and the vegetable oil allows a uniform distribution of vegetable oil droplets in the epoxy medium. This novel approach to creating a dispersed phase-change material made a cured epoxy polymer containing up to 20% oil. The miscibility of epoxy resin and oil was studied by laser interferometry, and phase state diagrams of binary mixtures were calculated according to theory and experiments. A weak effect of oil on the viscosity and kinetics of the epoxy resin curing was demonstrated by rotational rheometry. According to differential scanning calorimetry and dynamic mechanical analysis, the oil plasticizes the epoxy matrix slightly, expanding its glass transition region towards low temperatures and reducing its elastic modulus. In the cured epoxy matrix, oil droplets have a diameter of 3–14 µm and are incapable of complete crystallization due to their multi-component chemical composition and non-disappeared limited miscibility. The obtained phase-change materials have relatively low specific energy capacity but can be used alternatively as self-lubricating low-noise materials due to dispersed oil, high stiffness, and reduced friction coefficient. Palm oil crystallizes more readily, better matching the creation of phase-change materials, whereas coconut oil crystallization is more suppressed, making it better for reducing the friction coefficient of the oil-containing material.

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“…The rheological behavior of emulsions is essential for comprehensive analysis, extending beyond stability assessments. The presence of nanoparticles can significantly affect the rheological properties of emulsions, leading to an increase in apparent viscosity, elastic modulus, and yield stress [11]. In addition, the stability of emulsions is critical for estimating their shelf life, and the physicochemical properties of emulsion systems, such as average diameter, polydispersity, and rheological properties, are essential for assessing system stability [12].…”

Section: Introductionmentioning

confidence: 99%

A Study on Emulsion Stabilization and Characterization of Rheological Properties of Tragacanth Gum

2023

IJANSER

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In this research, the effect of tragacanth concentration on the stability and rheological properties of emulsions is investigated. To assess the stability of emulsions containing different concentrations of tragacanth gum, emulsion stability index (ESI) values are measured. The emulsion stability significantly improved with increasing tragacanth gum concentration, as evidenced by reduced separation and creaming. The multifaceted interplay of various factors influencing emulsion stability is also highlighted. In addition, the role of emulsifier concentration in emulsion stability has been discussed, emphasizing the crucial balance required to prevent aggregation or excessive viscosity. Particle size distribution analysis demonstrated distinct size distributions in emulsions developed with different tragacanth gum concentrations with smaller and more uniform droplet sizes, indicating improved stability. The rheological properties of the emulsions have been investigated, revealing non-Newtonian behavior and a more pronounced shear thinning effect in emulsions with higher tragacanth gum content. The rheological behavior of the emulsions is effectively characterized by mathematical modeling using the power law model, providing insight into the shear-thinning behavior and flow resistance. The findings of the present study contribute to a comprehensive understanding of the impact of tragacanth gum concentration on emulsion stability and rheological properties, with implications for the development of tailored formulations suitable for various applications.

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Rheological properties of emulsions formed by polymer solutions and modified by nanoparticles

Cited by 17 publications

References 42 publications

Rheology and Miscibility of Linear/Hyperbranched Polydimethylsiloxane Blends and an Abnormal Decrease in Their Viscosity

Rheology and Miscibility of Linear/Hyperbranched Polydimethylsiloxane Blends and an Abnormal Decrease in Their Viscosity

Self-Lubricating and Shape-Stable Phase-Change Materials Based on Epoxy Resin and Vegetable Oils

A Study on Emulsion Stabilization and Characterization of Rheological Properties of Tragacanth Gum

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