Characterization, reactivity and rheological behaviour of metakaolin and Meta-halloysite based geopolymer binders

Multiscale hybrid composites were prepared using varying weight percentages (0 to 5) of multiwalled carbon nanotubes (MWCNTs) as nanofiller and a fixed weight percentage (20) of short glass fibres as micro filler (in polypropylene (PP) matrix. The shear and extensional viscosity of the composites was measured using a capillary rheometer. It was observed that even at higher shear rates the synergism of micro and nanofillers in the matrix significantly enhanced the melt viscosity. The complex nanotube network entanglement with micro fillers and PP chains imparted restrictions to the polymer chain movements. The prepared samples were subjected to thermal ageing at 100°C for 4 days in hot air oven. After ageing, multiscale composite with 3 wt% MWCNTs exhibited 28.57% enhancement in strain at break, whereas the tensile strength and modulus reduced by 6.8% and 8% respectively. The fracture toughness properties like strain energy release rate and critical stress intensity factor were not affected for multiscale composite at the optimum content of 3 wt% MWCNT, even after thermal ageing.

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Experimental and numerical investigation on the rheological behaviour of bituminous composites via DSR testing

Road Materials and Pavement Design ◽

10.1080/14680629.2021.1912812 ◽

2021 ◽

pp. 1-17

Author(s):

Elio Ziade ◽

Fateh Fakhari Tehrani ◽

Alain Beghin ◽

Christophe Petit ◽

Joseph Absi ◽

...

Keyword(s):

Numerical Investigation ◽

Rheological Behaviour ◽

Bituminous Composites

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Analytical Rheology of Honey: A State-of-the-Art Review

Foods ◽

10.3390/foods10081709 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1709

Author(s):

Célia Faustino ◽

Lídia Pinheiro

Keyword(s):

Sugar Content ◽

Rheological Behaviour ◽

Principal Component ◽

Rheological Parameters ◽

Experimental Conditions ◽

Thixotropic Behaviour ◽

Ancient Times ◽

Medicinal Properties ◽

Complex Relationships ◽

Temperature Time

Honey has been used as a nutraceutical product since ancient times due to its nutritional and medicinal properties. Honey rheology influences its organoleptic properties and is relevant for processing and quality control. This review summarizes the rheological behaviour of honeys of different botanical source(s) and geographical locations that has been described in the literature, focusing on the relation between rheological parameters, honey composition (moisture, water activity, sugar content, presence of colloidal matter) and experimental conditions (temperature, time, stress, shear rate). Both liquid and crystallized honeys have been addressed. Firstly, the main mathematical models used to describe honey rheological behaviour are presented highlighting moisture and temperature effects. Then, rheological data from the literature regarding distinct honey types from different countries is analysed and results are compared. Although most honeys are Newtonian fluids, interesting shear-thinning and thixotropic as well as anti-thixotropic behaviour have been described for some types of honey. Rheological parameters have also been successfully applied to identify honey adulteration and to discriminate between different honey types. Several chemometric techniques have also been employed to obtain the complex relationships between honey physicochemical and rheological properties, including partial least squares (PLS), principal component analysis (PCA) and artificial neural networks (ANN).

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Viscosity Model for Nanoparticulate Suspensions Based on Surface Interactions

Materials ◽

10.3390/ma14112752 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2752

Author(s):

Benedikt Finke ◽

Clara Sangrós Sangrós Giménez ◽

Arno Kwade ◽

Carsten Schilde

Keyword(s):

Mechanistic Model ◽

Model Development ◽

Rheological Behaviour ◽

Hybrid Modelling ◽

Shear Rates ◽

Drag Forces ◽

Boehmite Nanoparticles ◽

Data Points ◽

Two Parameters ◽

Physical Phenomena

In this paper, a widely mechanistic model was developed to depict the rheological behaviour of nanoparticulate suspensions with solids contents up to 20 wt.%, based on the increase in shear stress caused by surface interaction forces among particles. The rheological behaviour is connected to drag forces arising from an altered particle movement with respect to the surrounding fluid. In order to represent this relationship and to model the viscosity, a hybrid modelling approach was followed, in which mechanistic relationships were paired with heuristic expressions. A genetic algorithm was utilized during model development, by enabling the algorithm to choose among several hard-to-assess model options. By the combination of the newly developed model with existing models for the various physical phenomena affecting viscosity, it can be applied to model the viscosity over a broad range of solids contents, shear rates, temperatures and particle sizes. Due to its mechanistic nature, the model even allows an extrapolation beyond the limits of the data points used for calibration, allowing a prediction of the viscosity in this area. Only two parameters are required for this purpose. Experimental data of an epoxy resin filled with boehmite nanoparticles were used for calibration and comparison with modelled values.

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