Methods of testing plastics. Effect of temperature. Methods 105 and 106. Flow properties, shrinkage and after shrinkage

2015 ◽  
Keyword(s):  
Effect Of Temperature ◽  
Flow Properties

Flow Behaviors of Commercial Food Thickeners Used for the Management of Dysphagia: Effect of Temperature

2012 ◽  
Vol 8 (2) ◽  
Author(s):  
Se-Ra Hong ◽  
Dong-Soo Sun ◽  
Whachun Yoo ◽  
Byoungseung Yoo
Keyword(s):  
Shear Stress ◽  
Yield Stress ◽  
Flow Behavior ◽  
Effect Of Temperature ◽  
Rheological Parameters ◽  
High Shear ◽  
Flow Properties ◽  
Different Temperatures ◽  
Management Of Dysphagia ◽  
Arrhenius Temperature

Gum-based food thickeners are widely used to care for patients with dysphagia in Korea. In this study, the flow properties of commercially available gum-based food thickeners marketed in Korea were determined as a function of temperature. The flow properties of thickeners were determined based on the rheological parameters of the power law and Casson models. Changes in shear stress with the rate of shear (1-100 s-1) at different temperatures (5, 20, 35, and 50 oC) were independent of the type of thickener. All thickeners had high shear-thinning behavior (n=0.08-0.18) with yield stress at the different temperatures tested. In general, apparent viscosity (na,50) values progressively decreased with an increase in temperature. In addition, the consistency index (K) and Casson yield stress (σoc) values did not change much upon an increase in temperature from 5 to 35 oC, except for sample B. In the temperature range of 5-50 oC, the thickeners followed an Arrhenius temperature relationship with a high determination coefficient (R2=0.93-0.97): activation energies (Ea) for the flow of thickeners were in the range of 2.44 - 10.7 kJ/mol. Rheological parameters demonstrated considerable differences in flow behavior between the different gum-based food thickeners, indicating that their flow properties are related to the type of thickener and the flow properties of gum.

The Rheological Properties of Turkish Delight

2009 ◽  
Vol 6 (1) ◽  
Author(s):  
Zurriye Yilmaz ◽  
Mehmet Dogan ◽  
Mahir Alkan ◽  
Serap Dogan
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Power Law ◽  
Food Industry ◽  
Arrhenius Equation ◽  
Flow Behavior ◽  
Effect Of Temperature ◽  
Flow Properties ◽  
Different Temperatures ◽  
Dependent Flow

In the food industry, rheological properties, such as viscosity, shear rate, and shear stress, are the most important parameters required in the design of a technological process. Therefore, in this study, we determined the flow behavior and the time-dependent flow properties of Turkish Delight (TD) in the temperature range of 25-75°C using a capillar rheometer. The structure and thermal properties of TD were investigated by XRD and a simultaneous DTA/TG analysis. The shear rate values ranged from 5 to 300s-1. We found that: (i) TD behaved as non- Newtonian pseudoplastic foodstuff; (ii) while the measurement temperature increased, viscosity decreased; and (iii) TD was a rheopectic material. The effect of temperature on viscosity was described by means of the Arrhenius equation. The activation energies for the flow of pseudoplastic TD varied from 50.1-74.2 kJ/mol, depending on shear rate. Three models were used to predict the flow behavior of TD, namely, the Power law, Bingham and Casson models. The Power law model adequately described well the flow behavior of TD at different temperatures.

scholarly journals Encapsulation of Anthocyanins from Cornelian Cherry Fruits Using Heated or Non-Heated Soy Proteins

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1342
Author(s):  
Loredana Dumitrașcu ◽  
Nicoleta Stănciuc ◽  
Iuliana Aprodu
Keyword(s):  
Encapsulation Efficiency ◽  
Freeze Drying ◽  
Morphological Analysis ◽  
Soy Proteins ◽  
Effect Of Temperature ◽  
Low Density ◽  
Flow Properties ◽  
Cornelian Cherry ◽  
Heat Treated

In the current study, the effect of temperature on the potential of soy proteins to ensure the encapsulation and gastric stability of bioactives, such as anthocyanins from cornelian cherry fruits, was investigated. The powders obtained after freeze-drying were analyzed in relation to flow properties, encapsulation retention and efficiency, stability in simulated gastrointestinal medium, color, and morphology. Preheating the soy proteins generated a powder with low density. Powders obtained with native soy proteins allowed the highest encapsulation efficiency and the lowest was obtained when using preheated soy proteins. The heat treatment of the mixture of soy proteins and cornelian cherry fruits prior to encapsulation generated powders with the highest lightness and the lowest intensity of red shades among all samples. The in vitro experiments revealed that the highest protection in simulated gastric environment was provided when protein was heat treated either alone or in combination with bioactives to be encapsulated. The morphological analysis highlighted that powders consisted of large and rigid structures.

scholarly journals Rheological Behavior of Sumac (Rhus coriaria L.) Extract as Affected by Temperature and Concentration and Investigation of Flow Behavior with CFD

2020 ◽  
Vol 10 (6) ◽  
pp. 7120-7134
Keyword(s):  
Arrhenius Equation ◽  
Flow Behavior ◽  
Rheological Behaviour ◽  
Effect Of Temperature ◽  
Sudden Expansion ◽  
Flow Properties ◽  
Rotational Viscometer ◽  
Different Temperatures ◽  
Rhus Coriaria ◽  
Temperature Ranges

The purpose of this study is to investigate the rheological properties of sumac extract in different concentrations at different temperatures as well as its flow behavior in sudden expansion-contraction and at 90o elbow with CFD. The rheological behaviour of sumac extract in different concentrations (45.65%, 50.44%, 55.53%, 60.32%, and 65.13% total solids) were evaluated using a rotational viscometer at different temperatures (10, 20, 30, 40 and 50 C). Sumac extract samples showed Newtonian flow properties in these temperature ranges. Arrhenius equation was used to determine the effect of temperature. Ea value varied in the range of 11.16-34.35 kJ/mol, which diminished with a decrease in concentration. Power and Exponential models were used to characterize the effect of concentration on flow behavior. Time average velocity vector and contours, vorticity contours, kinetic energy contours, and pressure contours are given to show the flow behavior of sumac extract.

Processing, rheology and structure of melt compounded PBTclay nanocomposites having different chemical composition.

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Luigi Scatteia ◽  
Paola Scarfato ◽  
Domenico Acierno
Keyword(s):  
Flow Behavior ◽  
Relaxation Times ◽  
Empirical Method ◽  
Effect Of Temperature ◽  
Gradual Transition ◽  
Flow Properties ◽  
Butylene Terephthalate ◽  
Melt Compounding ◽  
The Matrix ◽  
Twin Screw

AbstractIn this study the melt flow behavior of poly(butylene terephthalate)-clay nanocomposites produced by melt compounding was investigated. Four commercial organo-modified montmorillonites, differing mainly by the organic treatment used in the modification, were employed as nanometric fillers and blended with the poly(butylene terephthalate) (PBT) at two weight percentages each (6 and 9wt%). The process was carried out using a laboratory-scale twin-screw extruder at two different extrusion rates, in order to evaluate the effect of the shear rate during the process on microstructure and flow properties. In this regard, the nanocomposite samples were submitted to morphological analyses and rheological measurements in the dynamic regime. The effect of temperature on the flow behavior of the hybrids with respect to the neat PBT matrix was also investigated. The obtained data were related to the hybrid compositions and then to the chemical affinity between polymer and clay type. All the reported results have shown a gradual transition from a pseudo-Newtonian trend towards a pseudo-solid-like flow behavior with the increase of the clay loading and the dispersion/exfoliation level of the clay particles, due to the corresponding increase of the polymer-silicate interactions that slow the relaxation times of the PBT chains. Moreover, it was also evident that for the fillers having the higher affinity towards the PBT the nano-scale dispersion benefit from higher residence times, and therefore slower extrusion rates; on the contrary, for the fillers having poor interaction with the polymer, higher shear stress, and therefore higher extrusion rates, are needed to disrupt the clay tactoids in smaller particles. In the last part of the work, in order to verify if a relationship between flow properties and degree of exfoliation does actually exist, the rheological data were also processed using a simple semi-quantitative empirical method proposed in literature. The method failed for our systems, thus underlining the insufficiency of the rheological response alone in quantifying the exfoliation degree of an organoclay in the matrix.

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