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

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

Diblock copolymer architecture and complex viscosity

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040110 ◽  
Author(s):  
Mona A. Kanso ◽  
A. Jeffrey Giacomin ◽  
Chaimongkol Saengow ◽  
Jourdain H. Piette
Keyword(s):  
Diblock Copolymer ◽  
Linear Density ◽  
Complex Viscosity ◽  
Chem Phys ◽  
Dimensionless Frequency ◽  
Zero Shear Viscosity ◽  
Polymeric Liquids ◽  
Rod Theory ◽  
Number Ratio ◽  
Polymer Viscoelasticity

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.

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

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

<P>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. </P><P> Objective: This study aims to investigate the effects of &#954;-carrageenan, modified starch and inulin addition on rheological and sensory properties of non-fat and non-added sugar dairy dessert. </P><P> 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 &#948;) and complex viscosity (&#951;*) 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. </P><P> Results: All treatments showed a viscoelastic gel structure with the storage modulus higher than the loss modulus values. Increasing amounts of &#954;-carrageenan and modified starch caused an increase in G′ and G″ as well as &#951;* and a decrease in tan &#948;. Also, firmness and cohesiveness were enhanced. The trained panelists gave the highest score to the treatment with 0.1% &#954;-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. </P><P> Conclusion: It can be concluded that the concentration of &#954;-carrageenan and starch strongly influenced the rheological and textural properties of dairy desserts, whereas the inulin content had little effect on these attributes.</P>

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

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.

scholarly journals 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 ◽  
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.

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

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4433 ◽  
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.

scholarly journals A discrete mechanics approach to the Cosserat rod theory-Part 1: static equilibria

2010 ◽  
Vol 85 (1) ◽  
pp. 31-60 ◽  
Author(s):  
Pascal Jung ◽  
Sigrid Leyendecker ◽  
Joachim Linn ◽  
Michael Ortiz
Keyword(s):  
Discrete Mechanics ◽  
Rod Theory ◽  
Cosserat Rod

Energy Harvesting With Piezoelectric Nanobrushes: Analysis and Design Principles

2009 ◽  
Author(s):  
Carmel Majidi ◽  
Mikko Haataja ◽  
David J. Srolovitz
Keyword(s):  
Energy Harvesting ◽  
Design Space ◽  
Electronic Devices ◽  
Wearable Electronics ◽  
Nanostructured Surface ◽  
Elastic Rod ◽  
Analysis And Design ◽  
Rod Theory ◽  
Piezoelectric Energy ◽  
Self Powered

The development of self-powered electronic devices is essential for emerging technologies such as wireless sensor networks, wearable electronics, and microrobotics. Of particular interest is the rapidly growing field of piezoelectric energy harvesting (PEH), in which mechanical strains are converted to electricity. Recently, PEH has been demonstrated by brushing an array of piezoelectric nanowires against a nanostructured surface. The piezoelectric nanobrush generator can be limited to sub-micron dimensions and thus allows for a vast reduction in the size of self-powered devices. Moreover, energy harvesting is controlled through contact between the nanowire tips and nanostructured surface, which broadens the design space to a wealth of innovations in tribology. Here we propose design criteria based on principles of contact mechanics, elastic rod theory, and continuum piezoelasticity.

Rheological Behavior and Microstructure of Flame Retardant Polypropylene Composites

2010 ◽  
Author(s):  
Guo Jiang ◽  
Kai Liao ◽  
Juan-Juan Han ◽  
De-Xian Feng ◽  
Han-Xiong Huang
Keyword(s):  
Magnesium Hydroxide ◽  
Shear Viscosity ◽  
Flame Retardancy ◽  
Rheological Behavior ◽  
Oxygen Index ◽  
Complex Viscosity ◽  
Test Results ◽  
Screw Extruder ◽  
Polypropylene Composites ◽  
Twin Screw

Polypropylene (PP)/magnesium hydroxide (MDH) composite was melt-mixed using a twin-screw extruder. Two types of MDH were used, one with the modification of silane and another without. The rheological behavior was measured by capillary and dynamical rheometer. Microstructure of these composites was observed by SEM. Their flame retardancy was characterized by oxygen index and Horizontal/Vertical burning test. Results showed that shear viscosity and complex viscosity of PP with modified MDH were lower than that of PP with non-modified MDH. SEM results also showed a better dispersion of silane modified MDH in PP matrix. With the increase of MDH content, the oxygen index of composites was increased. When the content was increased to 60 wt%, the composite was UL94 HB and V-1.

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