Gels | Special Issue : Advances in Polymer Rheology

Research

11 pages, 1928 KiB

Open AccessArticle

Rheological and Micro-Rheological Properties of Chicory Inulin Gels

by Jingyuan Xu and James A. Kenar

Gels 2024, 10(3), 171; https://doi.org/10.3390/gels10030171 - 28 Feb 2024

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As a soluble fiber, inulin is present in many plants and has many applications in food and non-food products. In this work, we investigated the rheological properties of inulin dispersions at seven concentrations. The linear viscoelastic properties of inulin were determined using a [...] Read more.

As a soluble fiber, inulin is present in many plants and has many applications in food and non-food products. In this work, we investigated the rheological properties of inulin dispersions at seven concentrations. The linear viscoelastic properties of inulin were determined using a conventional mechanical rheometer. At 25 wt%, inulin exhibited fluid-like viscoelastic liquid behavior. However, when concentrations were ≥27.5 wt%, inulin exhibited gel-like viscoelastic properties. The viscoelastic properties (moduli and viscosities) increased with increasing inulin concentration. The high-frequency linear rheological properties of inulin were also investigated using the modern light scattering technique, diffusion wave spectroscopy (DWS). The diffusion wave spectroscopy (DWS) measurements showed the amplitude of complex moduli (|G*(ω)|) of inulin gels (≥27.5 wt%) to be proportional to ½ power law of the frequency, which suggests inulin gels behave similarly to flexible polymers. The non-linear steady shear experiments demonstrated that inulin exhibited shear-thinning behavior that was well fitted by a power law constitutive model. The trend of the power law exponent from the experiments indicated that the shear-thinning extent for inulin was greater as the inulin concentration increased. The results of this work indicated that the properties of inulin gel can be manipulated by altering its concentration. Therefore, the desired inulin product can be designed accordingly. These results can be used to direct further food and non-food applications, such as wound healing materials for inulin gels. Full article

(This article belongs to the Special Issue Advances in Polymer Rheology)

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17 pages, 3714 KiB

Open AccessArticle

Flaxseed Gum/Arabic Gum/Tween 80-Based Oleogel as a Fat Substitute Applied in Emulsified Sausage: Physicochemical Properties, Sensory Attributes and Nutritional Quality

by Qiaomei Zhu, Fu Chen, Peiyang Li, Tao Wu, Yijun Pan and Min Zhang

Gels 2023, 9(9), 759; https://doi.org/10.3390/gels9090759 - 18 Sep 2023

Viewed by 1408

Abstract

In the present study, flaxseed gum (FG), Arabic gum (GA) and Tween 80 were used to prepare oleogels through an emulsion-templated method, and the obtained oleogels were designed for the partial substitution of pork fat in emulsified sausage. An increment in FG concentrations [...] Read more.

In the present study, flaxseed gum (FG), Arabic gum (GA) and Tween 80 were used to prepare oleogels through an emulsion-templated method, and the obtained oleogels were designed for the partial substitution of pork fat in emulsified sausage. An increment in FG concentrations enhanced the viscoelasticity of emulsions, which resulted in the improved stability of emulsion systems, with smaller droplet sizes. In addition, increased FG concentrations contributed to higher mechanical strength, denser network structure and lower oil loss of oleogels. As a fat substitute, the prepared oleogels improved the textural properties and nutritional quality of emulsified sausages. With the increase in the substitution level of oleogels, the hardness and chewiness of the emulsified sausage increased, and the cooking loss decreased. Meanwhile, the reformulation with oleogels decreased the saturated fat from 57.04 g/100 g lipid to 12.05 g/100 g lipid, while increasing the ratio of omega-6 to omega-3 essential fatty acids from 0.10 to 0.39. The obtained results demonstrated that the flaxseed gum/Arabic gum/Tween 80-based oleogels had huge potential to successfully replace pork fat in emulsified sausage products. Full article

(This article belongs to the Special Issue Advances in Polymer Rheology)

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10 pages, 3518 KiB

Open AccessArticle

Anomalous Magnetorheological Response for Carrageenan Magnetic Hydrogels Prepared by Natural Cooling

by Masahiro Kaneko, Mika Kawai and Tetsu Mitsumata

Gels 2023, 9(9), 691; https://doi.org/10.3390/gels9090691 - 28 Aug 2023

Cited by 1 | Viewed by 708

Abstract

The effect of the cooling rate on magnetorheological response was investigated for magnetic hydrogels consisting of carrageenan and carbonyl iron particles with a concentration of 50 wt.%. For magnetic gels prepared via natural cooling, the storage moduli at 0 and 50 mT were [...] Read more.

The effect of the cooling rate on magnetorheological response was investigated for magnetic hydrogels consisting of carrageenan and carbonyl iron particles with a concentration of 50 wt.%. For magnetic gels prepared via natural cooling, the storage moduli at 0 and 50 mT were 3.7 × 10⁴ Pa and 5.6 × 10⁴ Pa, respectively, and the change in the modulus was 1.9 × 10⁴ Pa. For magnetic gels prepared via rapid cooling, the storage moduli at 0 and 50 mT were 1.2 × 10⁴ Pa and 1.8 × 10⁴ Pa, respectively, and the change in the modulus was 6.2 × 10³ Pa, which was 1/3 of that for the magnetic gel prepared by natural cooling. The critical strains, where G′ is equal to G″ on the strain dependence of the storage modulus, for magnetic gels prepared by natural cooling and rapid cooling, were 0.023 and 0.034, respectively, indicating that the magnetic gel prepared by rapid cooling has a hard structure compared to that prepared by natural cooling. Opposite to this, the change in the storage modulus at 500 mT for the magnetic gel prepared by rapid cooling was 1.6 × 10⁵ Pa, which was 2.5 times higher than that prepared by natural cooling. SEM images revealed that many small aggregations of the carrageenan network were found in the magnetic gel prepared by natural cooling, and continuous phases of carrageenan network with large sizes were found in the magnetic gel prepared by rapid cooling. It was revealed that magnetic particles in the magnetic gel prepared by rapid cooling can move and form a chain structure at high magnetic fields by breaking the restriction from the continuous phases of carrageenan. Full article

(This article belongs to the Special Issue Advances in Polymer Rheology)

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16 pages, 2603 KiB

Open AccessArticle

Rheological Characteristics of Soluble Cress Seed Mucilage and β-Lactoglobulin Complexes with Salts Addition: Rheological Evidence of Structural Rearrangement

by Afsaneh Taheri, Mahdi Kashaninejad, Ali Mohammad Tamaddon, Juan Du and Seid Mahdi Jafari

Gels 2023, 9(6), 485; https://doi.org/10.3390/gels9060485 - 13 Jun 2023

Cited by 2 | Viewed by 1382

Abstract

Functional, physicochemical, and rheological properties of protein–polysaccharide complexes are remarkably under the influence of the quality of solvent or cosolute in a food system. Here, a comprehensive description of the rheological properties and microstructural peculiarities of cress seed mucilage (CSM)-β-lactoglobulin (Blg) complexes are [...] Read more.

Functional, physicochemical, and rheological properties of protein–polysaccharide complexes are remarkably under the influence of the quality of solvent or cosolute in a food system. Here, a comprehensive description of the rheological properties and microstructural peculiarities of cress seed mucilage (CSM)-β-lactoglobulin (Blg) complexes are discussed in the presence of CaCl₂ (2–10 mM), (CSM–Blg–Ca), and NaCl (10–100 mM) (CSM–Blg–Na). Our results on steady-flow and oscillatory measurements indicated that shear thinning properties can be fitted well by the Herschel–Bulkley model and by the formation of highly interconnected gel structures in the complexes, respectively. Analyzing the rheological and structural features simultaneously led to an understanding that formations of extra junctions and the rearrangement of the particles in the CSM–Blg–Ca could enhance elasticity and viscosity, as compared with the effect of CSM–Blg complex without salts. NaCl reduced the viscosity and dynamic rheological properties and intrinsic viscosity through the salt screening effect and dissociation of structure. Moreover, the compatibility and homogeneity of complexes were approved by dynamic rheometry based on the Cole–Cole plot supported by intrinsic viscosity and molecular parameters such as stiffness. The results outlined the importance of rheological properties as criteria for investigations that determine the strength of interaction while facilitating the fabrication of new structures in salt-containing foods that incorporate protein–polysaccharide complexes. Full article

(This article belongs to the Special Issue Advances in Polymer Rheology)

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14 pages, 3024 KiB

Open AccessArticle

Correlation between Physical Properties of 12-Hydroxystearic Acid Organogels and Hansen Solubility Parameters

by Yuya Murakami, Taisei Uchiyama and Atsushi Shono

Gels 2023, 9(4), 314; https://doi.org/10.3390/gels9040314 - 7 Apr 2023

Viewed by 1342

Abstract

The Hansen solubility parameter (HSP) is a useful index for reasoning the gelation behavior of low-molecular-weight gelators (LMWGs). However, the conventional HSP-based methods only “classify” solvents that can and cannot form gels and require many trials to achieve this. For engineering purposes, quantitative [...] Read more.

The Hansen solubility parameter (HSP) is a useful index for reasoning the gelation behavior of low-molecular-weight gelators (LMWGs). However, the conventional HSP-based methods only “classify” solvents that can and cannot form gels and require many trials to achieve this. For engineering purposes, quantitative estimation of gel properties using the HSP is highly desired. In this study, we measured critical gelation concentrations based on three distinct definitions, mechanical strength, and light transmittance of organogels prepared with 12-hydroxystearic acid (12HSA) and correlated them with the HSP of solvents. The results demonstrated that the mechanical strength, in particular, strongly correlated with the distance of 12HSA and solvent in the HSP space. Additionally, the results indicated that the constant volume-based concentration should be used when comparing the properties of organogels to a different solvent. These findings are helpful in efficiently determining the gelation sphere of new LMWGs in HSP space and contribute to designing organogels with tunable physical properties. Full article

(This article belongs to the Special Issue Advances in Polymer Rheology)

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13 pages, 2932 KiB

Open AccessArticle

Effect of Hydrogen Bonding on Dynamic Rheological Behavior of PVA Aqueous Solution

by Qingsheng Ni, Weijuan Ye, Miao Du, Guorong Shan, Yihu Song and Qiang Zheng

Gels 2022, 8(8), 518; https://doi.org/10.3390/gels8080518 - 19 Aug 2022

Cited by 8 | Viewed by 1903

Abstract

The rheological behavior of polyvinyl alcohol (PVA) aqueous solution is crucial to optimizing the processing technology and performance of PVA products. In this paper, the dynamic rheological behavior of PVA aqueous solution was investigated in detail. PVA solution with a concentration of 10 [...] Read more.

The rheological behavior of polyvinyl alcohol (PVA) aqueous solution is crucial to optimizing the processing technology and performance of PVA products. In this paper, the dynamic rheological behavior of PVA aqueous solution was investigated in detail. PVA solution with a concentration of 10 wt% showed unnormal rheological behaviors, that is, the liquid-like behavior in the high frequency (ω) region and the solid-like behavior in the low ω region. A storage modulus (G′) plateau appears in the relatively low ω region as a gel with a network structure. Different from conventional hydrogel, this plateau has a low modulus, and the corresponding size of the relaxation unit is estimated to be 554 nm, being higher than the size of a whole PVA chain. It is believed that the network mesh is formed by the intermolecular hydrogen bonding interactions among PVA chains. The relaxation time of these meshes is longer than the reptation time of a PVA chain. Based on the relaxation spectrum and calculation analysis, it is found that the destruction of intermolecular hydrogen bonds, such as by heating up, adding sodium dodecyl sulfate, and shear operation, will make the relaxation unit (mesh) larger and lead to the left shift of the intersection of G′ and loss modulus (G″). In a PVA solution with a high concentration, multiple meshes of various sizes could be formed and thus generate multiple relaxation peaks. The large-sized meshes mainly contribute to the left shift of the intersection of G′ and G″, and the small-sized meshes contribute to the high plateau modulus. The results in this paper offer a new angle to analyze polymer solutions with strong intermolecular interaction. Full article

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14 pages, 3496 KiB

Open AccessArticle

Linking Processing Parameters and Rheology to Optimize Additive Manufacturing of k-Carrageenan Gel Systems

by Simona Russo Spena, Nino Grizzuti and Daniele Tammaro

Gels 2022, 8(8), 493; https://doi.org/10.3390/gels8080493 - 9 Aug 2022

Cited by 10 | Viewed by 1709

Abstract

Additive manufacturing—in particular, three-dimensional (3D) printing—has been introduced since the late 1980s, offering a novel paradigm for engineering design and manufacturing, as it allows the fabrication of very complex structures. Additive manufacturing of hydrogels is a very popular method to produce scaffolds to [...] Read more.

Additive manufacturing—in particular, three-dimensional (3D) printing—has been introduced since the late 1980s, offering a novel paradigm for engineering design and manufacturing, as it allows the fabrication of very complex structures. Additive manufacturing of hydrogels is a very popular method to produce scaffolds to be used in tissue engineering and other biomedical applications, as well as in other advanced technological areas. When printing a thermoreversible physical hydrogel, a subtle balance between thermal and rheological parameters exists. The characteristic times of the sol–gel transition, regulated by a well-defined thermal history, must be optimized with respect to the characteristic processing times. In this work, we use this thermo-rheological approach to the additive manufacturing of a physical hydrogel. A low-cost desktop 3D printer for thermoplastic polymers was suitably modified to print a 1.5 wt% solution of k-carrageenan. The thermal behavior of the printer was determined by performing experimental measurements of the temperature–time evolution during the different processing steps, from solution loading, to the extrusion of the incoming gel, to the final solidification stage. In parallel, linear viscoelastic oscillatory shear measurements were performed in a rotational rheometer under thermal histories as close as possible to those previously measured in the printing process. The comparison between the rheological results and the quality of printing under different thermal histories is presented and discussed, highlighting the main relations between rheological and processing behavior, which are helpful in the assessment and optimization of the printing conditions. Full article

(This article belongs to the Special Issue Advances in Polymer Rheology)

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14 pages, 4411 KiB

Open AccessArticle

Effect of Morphology/Structure on the Phase Behavior and Nonlinear Rheological Properties of NR/SBR Blends

by Li Yang, Xuanyu Shi, Shihao Sun, Jun Zhong, Xiaofeng Yu, Danling Wang, Yihu Song, Min Zuo and Qiang Zheng

Gels 2022, 8(7), 425; https://doi.org/10.3390/gels8070425 - 7 Jul 2022

Cited by 1 | Viewed by 1762

Abstract

The evolution of the morphology/structure and the nonlinear viscoelasticity of rubber blends under large amounts of strain are key scientific issues for the design and manufacture of rubber blends. The rheological responses of natural rubber/styrene-butadiene rubber (NR/SBR) blends are traced over a wide [...] Read more.

The evolution of the morphology/structure and the nonlinear viscoelasticity of rubber blends under large amounts of strain are key scientific issues for the design and manufacture of rubber blends. The rheological responses of natural rubber/styrene-butadiene rubber (NR/SBR) blends are traced over a wide range of blend compositions to gain an insight into the effect of blend morphology on their nonlinear viscoelasticity. We also prepare NR + SBR physical blends without melt mixing to distinguish the contributions of composition and blend morphology to the viscoelastic response. The microscopic heterogeneous gel-like structure of NR/SBR blends may remarkably weaken their strain softening and improve their modulus hysteretic recovery under large strain, which may be attributed to the heterogeneous microscopic deformation for the NR and SBR phases. Furthermore, additional elastic contribution resulted from the increasing interfacial energy of domain deformation. This may provide some new insights into the effect of blend morphology on the Payne effect of rubber blends. Full article

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13 pages, 39203 KiB

Open AccessArticle

Application of Xanthan Gum and Hyaluronic Acid as Dermal Foam Stabilizers

by Fanni Falusi, Szilvia Berkó, Anita Kovács and Mária Budai-Szűcs

Gels 2022, 8(7), 413; https://doi.org/10.3390/gels8070413 - 30 Jun 2022

Cited by 2 | Viewed by 1962

Abstract

Foams are increasingly popular in the field of dermatology due to their many advantages such as easy spreading, good skin sensation, and applicability in special skin conditions. One of the critical points of foam formulation is the choice of the appropriate stabilizing ingredients. [...] Read more.

Foams are increasingly popular in the field of dermatology due to their many advantages such as easy spreading, good skin sensation, and applicability in special skin conditions. One of the critical points of foam formulation is the choice of the appropriate stabilizing ingredients. One of the stability-increasing strategies is retarding the liquid drainage of liquid films from the foam structure. Therefore, our aim was the application of different hydrogel-forming polymers in order to retain the stabilizing liquid film. Dexpanthenol and niacinamide-containing foams were formulated, where xanthan gum and hyaluronic acid were used as foam-stabilizing polymers. Amplitude (LVE range) and frequency sweep (G’, G”, tanδ, and frequency dependency) were applied as structure- and stability-indicating rheological parameters. The rheological data were compared with the results of the cylinder method, microscopical images, and the spreadability measurements. The application of the gel-forming polymers increased the stability of the dermal foams (increased LVE range, G’ values, and decreased frequency dependency). These results were in correlation with the results of the cylinder and spreadability tests. It was concluded that in terms of both foam formation and stability, the combination of xanthan gum and dexpanthenol can be ideal. Full article

(This article belongs to the Special Issue Advances in Polymer Rheology)

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