Complex viscosity of helical and doubly helical polymeric liquids from general rigid bead-rod theory

General rigid bead-rod theory [O. Hassager, J. Chem. Phys. 60, 4001 (1974)] explains polymer viscoelasticity from macromolecular orientation. By means of general rigid bead-rod theory, we relate the complex viscosity of polymeric liquids to the architecture of axisymmetric macromolecules. In this paper, we explore the complex viscosities of different axisymmetric diblock copolymer configurations. When nondimensionalized with the zero-shear viscosity, the diblock copolymer complex viscosity depends on the dimensionless frequency and the sole dimensionless architectural parameter, the macromolecular lopsidedness. In this paper, through this way, we thus compare the dimensionless relaxation time of different diblock macromolecular chains. We explore the effects of linear density, macromolecular length, and bead number ratio.

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Complex viscosity of star-branched macromolecules from analytical general rigid bead-rod theory

Physics of Fluids ◽

10.1063/5.0063199 ◽

2021 ◽

Vol 33 (9) ◽

pp. 093111

Author(s):

S. J. Coombs ◽

M. A. Kanso ◽

K. El Haddad ◽

A. J. Giacomin

Keyword(s):

Complex Viscosity ◽

Rod Theory

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Influence of κ-Carrageenan, Modified Starch and Inulin Addition on Rheological and Sensory Properties of Non-fat and Non-added Sugar Dairy Dessert

Current Nutrition & Food Science ◽

10.2174/1573401315666190301152645 ◽

2020 ◽

Vol 16 (4) ◽

pp. 462-469

Author(s):

Zhaleh Sheidaei ◽

Bahareh Sarmadi ◽

Seyede M. Hosseini ◽

Fardin Javanmardi ◽

Kianoush Khosravi-Darani ◽

...

Keyword(s):

Storage Modulus ◽

Loss Modulus ◽

Viscoelastic Behavior ◽

Textural Properties ◽

Complex Viscosity ◽

Sensory Properties ◽

Modified Starch ◽

Consumer Health ◽

Added Sugar ◽

Textural Parameters

Background: The high amounts of fat, sugar and calorie existing in dairy desserts can lead to increase the risk of health problems. Therefore, the development of functional and dietary forms of these products can help the consumer health. Objective: This study aims to investigate the effects of κ-carrageenan, modified starch and inulin addition on rheological and sensory properties of non-fat and non-added sugar dairy dessert. Methods: In order to determine the viscoelastic behavior of samples, oscillatory test was carried out and the values of storage modulus (G′), loss modulus (G″), loss angle tangent (tan δ) and complex viscosity (η*) were measured. TPA test was used for analysis of the desserts’ texture and textural parameters of samples containing different concentrations of carrageenan, starch and inulin were calculated. Results: All treatments showed a viscoelastic gel structure with the storage modulus higher than the loss modulus values. Increasing amounts of κ-carrageenan and modified starch caused an increase in G′ and G″ as well as η* and a decrease in tan δ. Also, firmness and cohesiveness were enhanced. The trained panelists gave the highest score to the treatment with 0.1% κ-carrageenan, 2.5% starch and 5.5% inulin (sucralose as constant = 0.25%) and this sample was the best treatment with desirable attributes for the production of non-fat and non-added sugar dairy dessert. Conclusion: It can be concluded that the concentration of κ-carrageenan and starch strongly influenced the rheological and textural properties of dairy desserts, whereas the inulin content had little effect on these attributes.

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Electrical conductivity and rheological properties of carbon black based conductive polymer composites prior to and after annealing

Polymers and Polymer Composites ◽

10.1177/09673911211001277 ◽

2021 ◽

pp. 096739112110012

Author(s):

Qingsen Gao ◽

Jingguang Liu ◽

Xianhu Liu

Keyword(s):

Electrical Conductivity ◽

Carbon Black ◽

Percolation Threshold ◽

Rheological Properties ◽

Network Formation ◽

Loss Modulus ◽

Conductive Polymer ◽

Complex Viscosity ◽

Electrical Percolation ◽

Electrical Percolation Threshold

The effect of annealing on the electrical and rheological properties of polymer (poly (methyl methacrylate) (PMMA) and polystyrene (PS)) composites filled with carbon black (CB) was investigated. For a composite with CB content near the electrical percolation threshold, the formation of conductive pathways during annealing has a significant impact on electrical conductivity, complex viscosity, storage modulus and loss modulus. For the annealed samples, a reduction in the electrical and rheological percolation threshold was observed. Moreover, a simple model is proposed to explain these behaviors. This finding emphasizes the differences in network formation with respect to electrical or rheological properties as both properties belong to different physical origins.

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A Characterization Study of Morphology and Properties of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)/Aloe Vera Fibers Biocomposites: Effect of Fiber Surface Treatments

Proceedings ◽

10.3390/cgpm2020-07183 ◽

2020 ◽

Vol 69 (1) ◽

pp. 38

Author(s):

Celia Idres ◽

Mustapha Kaci ◽

Nadjet Dehouche ◽

Idris Zembouai ◽

Stéphane Bruzaud

Keyword(s):

Thermal Stability ◽

Surface Morphology ◽

Water Absorption ◽

Loss Modulus ◽

Aloe Vera ◽

Fiber Surface ◽

Complex Viscosity ◽

Absorption Capacity ◽

Characterization Study ◽

Efficient Route

This paper aims to investigate the effect of different chemical modifications of biocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) and aloe vera bio-fibers incorporated at 20 wt%. The fiber surface was modified with alkaline, organosilanes, and combined alkaline/organosilanes. Surface morphology, thermal stability, water absorption capacity, and rheological behavior of the modified biocomposite materials were studied, and the results compared to both unmodified biocomposites and neat PHBH. The study showed that the modified biocomposites with both alkaline and organosilanes exhibited an improved surface morphology, resulting in a good fiber/matrix interfacial adhesion. As a result, increases in complex viscosity, storage modulus, and loss modulus were observed, whereas water absorption was reduced. Thermal stability remained almost unchanged, with the exception of the biocomposite treated with alkaline, where this property decreased significantly. Finally, the coupling of alkaline and organosilane modification is an efficient route to enhance the properties of PHBH biocomposites.

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Electrokinetics of polymeric fluids in narrow rectangular confinements

Soft Matter ◽

10.1039/d1sm00537e ◽

2021 ◽

Author(s):

Aditya Natu ◽

Uddipta Ghosh

Keyword(s):

Cross Section ◽

Rectangular Cross Section ◽

Double Layers ◽

Polymeric Fluids ◽

Polymeric Liquids ◽

Electrical Double Layers

Flow of polymeric liquids in narrow confinements of rectangular cross section, in the presence of electrical double layers is analyzed here. Our analysis is motivated by the fact that many...

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Rheological, Thermal, Superficial, and Morphological Properties of Thermoplastic Achira Starch Modified with Lactic Acid and Oleic Acid

Molecules ◽

10.3390/molecules24244433 ◽

2019 ◽

Vol 24 (24) ◽

pp. 4433 ◽

Cited By ~ 2

Author(s):

Carolina Caicedo ◽

Rocío Yaneli Aguirre Loredo ◽

Abril Fonseca García ◽

Omar Hernán Ossa ◽

Aldo Vázquez Arce ◽

...

Keyword(s):

Lactic Acid ◽

Oleic Acid ◽

Complex Viscosity ◽

Thermoplastic Starch ◽

Residual Energy ◽

Morphological Properties ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Rheological Analysis ◽

Acid Agent

The modification of achira starch a thermoplastic biopolymer is shown. Glycerol and sorbitol, common plasticizers, were used in the molten state with organic acids such as oleic acid and lactic acid obtaining thermodynamically more stable products. The proportion of starch:plasticizer was 70:30, and the acid agent was added in portions from 3%, 6%, and 9% by weight. These mixtures were obtained in a torque rheometer for 10 min at 130 °C. The lactic acid managed to efficiently promote the gelatinization process by increasing the available polar sites towards the surface of the material; as a result, there were lower values in the contact angle, these results were corroborated with the analysis performed by differential scanning calorimetry and X-ray diffraction. The results derived from oscillatory rheological analysis had a viscous behavior in the thermoplastic starch samples and with the presence of acids; this behavior favors the transitions from viscous to elastic. The mixture of sorbitol or glycerol with lactic acid promoted lower values of the loss module, the storage module, and the complex viscosity, which means lower residual energy in the transition of the viscous state to the elastic state; this allows the compounds to be scaled to conventional polymer transformation processes.

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