Freezing as a Storage Process for Aqueous Polymer Solutions

2005 ◽  
Vol 15 (2) ◽  
pp. 90-97 ◽  
Author(s):  
M. P. Escudier ◽  
J. Clement-Evans ◽  
R. J. Poole
Keyword(s):  
Rheological Properties ◽  
Xanthan Gum ◽  
Storage Process ◽  
Polymeric Liquids ◽  
Freeze Thaw ◽  
Aqueous Polymer ◽  
Before And After ◽  
Novel Method ◽  
Normal Stress Differences ◽  
Initial Preparation

Abstract There is often a need to perform rheological tests on dilute polymeric liquids at a time long after their initial preparation, for example if a more sensitive or novel method of measuring a material property (such as uniaxial/biaxial extensional viscosity or second normal-stress differences) becomes available. An inexpensive method of storing such fluids which prevents any form of deterioration (e.g. bacteriological) would therefore be of great value. This study explores the potential of freezing as that storage process by investigating whether the freeze-thaw process itself leads to rheological changes. The rheological properties of three polymeric liquids: 0.25 % xanthan gum, 0.125% polyacrylamide and a 0.1 %/0.1 % carboxymethylcellulose / xanthan gum blend commonly used in non-Newtonian fluid flow studies were determined in both shear and oscillation before and after a freeze-thaw process. Within the uncertainty of the rheometer used, the rheological properties of the polymers studied were found to be unaffected by the freeze-thaw process leading to the conclusion that this storage method is indeed a practical possibility.

scholarly journals Rheological Properties of Aqueous Dispersions of Xanthan Gum Containing Different Chloride Salts Are Impacted by both Sizes and Net Electric Charges of the Cations

2018 ◽  
Vol 13 (2) ◽  
pp. 186-197 ◽  
Author(s):  
Zoila Rosa Nieto Galván ◽  
Lucas de Souza Soares ◽  
Eber Antonio Alves Medeiros ◽  
Nilda de Fátima Ferreira Soares ◽  
Afonso Mota Ramos ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Xanthan Gum ◽  
Aqueous Dispersions ◽  
Chloride Salts

scholarly journals Assessment of Fennel Oil Microfluidized Nanoemulsions Stabilization by Advanced Performance Xanthan Gum

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 693
Author(s):  
Rubén Llinares ◽  
Pablo Ramírez ◽  
José Antonio Carmona ◽  
Luis Alfonso Trujillo-Cayado ◽  
José Muñoz
Keyword(s):  
Essential Oil ◽  
Rheological Properties ◽  
Xanthan Gum ◽  
Mechanical Energy ◽  
Physical Stability ◽  
Processing Condition ◽  
Oil In Water ◽  
Mechanical Spectra ◽  
The Stability ◽  
Fennel Oil

In this work, nanoemulsion-based delivery system was developed by encapsulation of fennel essential oil. A response surface methodology was used to study the influence of the processing conditions in order to obtain monomodal nanoemulsions of fennel essential oil using the microchannel homogenization technique. Results showed that it was possible to obtain nanoemulsions with very narrow monomodal distributions that were homogeneous over the whole observation period (three months) when the appropriate mechanical energy was supplied by microfluidization at 14 MPa and 12 passes. Once the optimal processing condition was established, nanoemulsions were formulated with advanced performance xanthan gum, which was used as both viscosity modifier and emulsion stabilizer. As a result, more desirable results with enhanced physical stability and rheological properties were obtained. From the study of mechanical spectra as a function of aging time, the stability of the nanoemulsions weak gels was confirmed. The mechanical spectra as a function of hydrocolloid concentration revealed that the rheological properties are marked by the biopolymer network and could be modulated depending on the amount of added gum. Therefore, this research supports the role of advanced performance xanthan gum as a stabilizer of microfluidized fennel oil-in-water nanoemulsions. In addition, the results of this research could be useful to design and formulate functional oil-in-water nanoemulsions with potential application in the food industry for the delivery of nutraceuticals and antimicrobials.

scholarly journals A Novel Method of Mechanical Oxidation of CNT for Polymer Nanocomposite Application: Evaluation of Mechanical, Dynamic Mechanical, and Rheological Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Priyanka Pandey ◽  
Smita Mohanty ◽  
Sanjay Kumar Nayak
Keyword(s):  
Rheological Properties ◽  
Load Transfer ◽  
Polymer Nanocomposite ◽  
Mechanical Analysis ◽  
Acid Oxidation ◽  
Reinforced Composites ◽  
Dynamic Mechanical ◽  
Comparative Aspect ◽  
Transfer Capability ◽  
Novel Method

A new approach of oxidation of carbon nanotubes has been used to oxidize the CNTs. A comparative aspect of the mechanical oxidation and acid oxidation process has been established. FTIR analysis and titration method have shown the higher feasibility of the mechanical oxidation method to oxidize the CNTs. Comparatively less damage to the CNTs has been observed in case of mechanically oxidized as compared to acid oxidized CNTs. The mechanical properties of the nanocomposites reinforced with the acid oxidized CNT (ACNT) and mechanically oxidized CNTs (McCNT) were analyzed and relatively higher properties in the nanocomposites reinforced with McCNT were noticed. The less degree of entanglement in the McCNTs was noticed as compared to ACNTs. The dynamic mechanical analysis of the nanocomposites revealed much improved load transfer capability in the McCNT reinforced composites. Further, the rheological properties of the nanocomposites revealed the higher performance of McCNT reinforced composites.

scholarly journals Application of a Liquid Chromatography Tandem Mass Spectrometry Method for the Simultaneous Detection of Seven Allergenic Foods in Flour and Bread and Comparison of the Method with Commercially Available ELISA Test Kits

2011 ◽  
Vol 94 (4) ◽  
pp. 1060-1068 ◽  
Author(s):  
Julia Heick ◽  
Markus Fischer ◽  
Sandra Kerbach ◽  
Ulrike Tamm ◽  
Bert Popping
Keyword(s):  
Simultaneous Detection ◽  
Elisa Test ◽  
Spectrometry Method ◽  
Chromatography Tandem Mass Spectrometry ◽  
Model Matrix ◽  
Before And After ◽  
Liquid Chromatography Tandem Mass ◽  
Novel Method ◽  
Detection Capabilities ◽  
Baked Products

Abstract To protect the allergic consumer, analytical methods need to be capable of detecting allergens in fnished products that typically contain multiple allergens. An LC/MS/MS method for simultaneous detection of seven allergens was developed and compared with commercially available ELISA kits. The detection capabilities of this novel method were demonstrated by analyzing incurred material containing milk, egg, soy, peanut, hazelnut, walnut, and almond. Bread was chosen as a model matrix. To assess the influence of baking on the method’s performance, analysis was done before and after baking. The same samples were analyzed with ELISA test kits from ELISA Systems, Morinaga, Neogen, and r-Biopharm. Peanut, hazelnut, walnut, and almond could be detected with both ELISA and LC/MS/MS regardless of whether the product was baked or not. LC/MS/MS clearly showed superior detection of milk in processed matrixes compared to ELISA, which exhibited signifcantly lower sensitivities when analyzing the baked products. Similar results were obtained when analyzing egg; however, one kit was capable of detecting egg in the processed samples as well.

scholarly journals Impact of freeze-thaw cytoablation on aqueous outflow patterns in ex vivo anterior chamber perfusion cultures and whole eyes

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 525
Author(s):  
Raoul Verma-Fuehring ◽  
Mohamad Dakroub ◽  
Alicja Strzalkowska ◽  
Piotr Strzalkowski ◽  
Hong Han ◽  
...  
Keyword(s):  
Trabecular Meshwork ◽  
Structural Changes ◽  
Ex Vivo ◽  
Anterior Segment ◽  
Large Change ◽  
Invasive Technique ◽  
Freeze Thaw ◽  
Before And After ◽  
Human Eyes ◽  
Porcine Eyes

Background: Porcine eyes have been widely used as ex vivo models in glaucoma research, as they share similar features with human eyes. Freeze-thawing is a non-invasive technique that has been used to obliterate living cells in anterior segment ex vivo cultures, to prepare them for further research such as cellular repopulation. This technique has previously been shown to reduce the intraocular pressure (IOP) in porcine eyes. The aim of this study was to investigate whether freeze-thaw cytoablation causes corresponding canalogram outflow changes in perfused anterior segment cultures (AFT) and whole porcine eyes (WFT). We hypothesized that the known IOP drop in AFT after trabecular meshwork ablation by freeze-thaw would be accompanied by a similarly large change in the distal outflow pattern. Methods: Two-dye (fluorescein and Texas red) reperfusion canalograms were used to compare the outflow time before and after two -80°C cycles of freeze-thaw. We assigned 28 freshly enucleated porcine eyes to four groups: perfused anterior segment dye controls (ACO, n = 6), perfused whole eye dye controls (WCO, n = 6), freeze-thaw treated anterior segment cultures (AFT, n = 10), and freeze-thaw treated whole eyes (WFT, n = 6). Results: In control groups ACO and WCO, the two different dyes had similar filling times. In AFT, the outflow pattern and filling times were unchanged. In WFT, the temporal superior quadrant filled more slowly (p = 0.042) while all others remained unchanged. The qualitative appearance of distal outflow spaces was altered only in some eyes. Conclusions: Freeze-thaw cytoablation caused neither loss nor leakage of distal outflow structures. Surprisingly, the loss of an intact trabecular meshwork over the entire circumference did not result in a general acceleration of quadrant outflow times. The results validate freeze-thawing as a method to generate an extracellular matrix without major structural changes.

scholarly journals Rheological behavior of cereal straw suspensions

2021 ◽  
Author(s):  
Sandra Ukaigwe
Keyword(s):  
Rheological Properties ◽  
Yield Stress ◽  
Rheological Behavior ◽  
Xanthan Gum ◽  
Mesh Size ◽  
General Purpose ◽  
Measuring Instrument ◽  
Fiber Concentration ◽  
Cereal Straw ◽  
Malt Barley

The rheological properties (yield stress and viscosity) of cereal straw suspensions are especially important in bioethanol production as they determine the mixing behaviour of the suspension during enzymatic hydrolysis. Yield stress measurements are generally difficult to perform in straw suspensions due to sedimentation, which commonly occur in the suspensions because of the difficulty encountered in loading the suspension into the measuring equipment. The process of placing the suspension in the measuring instrument causes a disturbance likely to induce the yielding of the suspension before the actual measurements are taken. Moreover cereal suspensions at high straw concentration (10-40 wt%) are soft solids and pourability is particularly difficult with solids. Rheological behavior of staw suspensions made from wheat, Oats and malt barley of fiber sizes 0.15 mm-4.20 mm (mesh sizes 20 to 100) and concentrations 5.0-15.0 wt% were studied. The suspensions were initially prepared by dispersing milled and sieved straws in distilled water at room temperature, followed by vortexing to aid the dispersion process; this was later modified to include a 30-minute de-aeration of the suspensions using vacuum and 2-minute mixing using a general purpose mixer at about 162 rpm. However, none these procedures produced a homogenous suspension. The viscosity of the dispersion medium was modified by the addition of Xanthan gum. This produced homogenous suspensions which remained suspended for about 20 minutes. The rheological properties of these suspensions were measured on a Bohlin rheometer in the controlled stress mode using a vane and cup measuring instrument, and the suspension yield stress determined by extrapolation and by regression of Herschel-Bulkley, Casson and Bingham models. Yield stress obtained from extrapolation ranged from 2-19 Pa, while model results ranged from 0.96- 8.15 Pa, for 5.0 wt% Oats straw suspensions with Xanthan gum strengths of 0.1-0.5 wt%. Extrapolation results for 7.5 wt% Oats staw suspensions with Xanthan gum strengths of 0.1-0.5 wt% ranged from 20-36 Pa while model results were in the range of 4.38-18.76 Pa. Wheat and malt barely straw suspensions evaluated using Herschel-Bulkley model at similiar Oats straw suspension conditions of 5.0 wt% fiber concentration with 0.3 wt% Xanthan gum strength produced statistically equivalent yields stress to Oats straw suspensions in the range of 2.31-4.04 Pa for fibers of mesh size 40-100. Cereal straw suspenions are non-Newtonian fluids with yield stresses that are highly straw concentration dependent.

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