scholarly journals Evaluating the Stability of Double Emulsions—A Review of the Measurement Techniques for the Systematic Investigation of Instability Mechanisms

2020 ◽  
Vol 4 (1) ◽  
pp. 8
Author(s):  
Nico Leister ◽  
Heike P. Karbstein
Keyword(s):  
Measurement Techniques ◽  
Double Emulsion ◽  
Systematic Investigation ◽  
Model Systems ◽  
Scanning Calorimetry ◽  
Contrast Model ◽  
Double Emulsions ◽  
Analysis Methods ◽  
The Stability

Double emulsions are very promising for various applications in pharmaceutics, cosmetics, and food. Despite lots of published research, only a few products have successfully been marketed due to immense stability problems. This review describes approaches on how to characterize the stability of double emulsions. The measurement methods are used to investigate the influence of the ingredients or the process on the stability, as well as of the environmental conditions during storage. The described techniques are applied either to double emulsions themselves or to model systems. The presented analysis methods are based on microscopy, rheology, light scattering, marker detection, and differential scanning calorimetry. Many methods for the characterization of double emulsions focus only on the release of the inner water phase or of a marker encapsulated therein. Analysis methods for a specific application rarely give information on the actual mechanism, leading to double emulsion breakage. In contrast, model systems such as simple emulsions, microfluidic emulsions, or single-drop experiments allow for a systematic investigation of diffusion and coalescence between the individual phases. They also give information on the order of magnitude in which they contribute to the failure of the overall system. This review gives an overview of various methods for the characterization of double emulsion stability, describing the underlying assumptions and the information gained. With this review, we intend to assist in the development of stable double emulsion-based products.

Behavior of silver nanoparticles in wastewater: systematic investigation on the combined effects of surfactants and electrolytes in model systems

2018 ◽  
Vol 4 (12) ◽  
pp. 2146-2159 ◽  
Author(s):  
Ivona Capjak ◽  
Maja Zebić Avdičević ◽  
Maja Dutour Sikirić ◽  
Darija Domazet Jurašin ◽  
Amela Hozić ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Water System ◽  
Systematic Investigation ◽  
Model Systems ◽  
Combined Effects ◽  
Test Water ◽  
System P ◽  
The Stability

pH, electrolytes and surfactants affected the stability of AgNPs in artificial test water system.

scholarly journals Effect of Selected Stabilizers and Processing Aids on the Stability of a Double Emulsion Encapsulating Bitter Gourd Extract

2021 ◽  
Author(s):  
Urmila Choudhary ◽  
Latha Sabikhi
Keyword(s):  
Double Emulsion ◽  
Gum Arabic ◽  
Sodium Caseinate ◽  
Bitter Gourd ◽  
Whey Protein Concentrate ◽  
Physical Parameters ◽  
Sedimentation Stability ◽  
Double Emulsions ◽  
The Stability ◽  
Emulsion Matrix

Effect of three variables in differing concentrations [NaCl (3-5%), polyglycerol polyricinoleate (PGPR) (2-4%) and dairy protein-polysaccharide complexes (Whey protein concentrate(WPC-80)-gum Arabic(GA) and sodium caseinate(SC)-gum Arabic in 1:2 ratio)] on the stability of W1/O/W2 emulsion matrix that was used to encapsulate bitter gourd extract was evaluated. The double emulsion matrix was characterized by apparent viscosity, zeta potential, turbidity and sedimentation stability by visual appearance. The physical parameters of the double emulsion matrix were very highly significantly (p < 0.001) affected by all variables such as the concentration of salt, PGPR and complex (WPC-GA and SC-P) as well as their interactions. The double emulsions prepared with WPC-GA became unstable immediately after preparation or after one day of preparation. SC-GA stabilized double emulsions were found more stable than WPC-GA stabilized emulsions. A double emulsion containing 5% NaCl, 2% PGPR and 16.5% SC-GA were found most stable (10 days at 37°C) in comparison to other combinations used.

scholarly journals Addition of Trans-Resveratrol-Loaded Highly Concentrated Double Emulsion to Yoghurts: Effect on Physicochemical Properties

2021 ◽  
Vol 23 (1) ◽  
pp. 85
Author(s):  
Rocío Díaz-Ruiz ◽  
Amanda Laca ◽  
Marta Sánchez ◽  
Manuel Ramón Fernández ◽  
María Matos ◽  
...  
Keyword(s):  
Antioxidant Capacity ◽  
Droplet Size ◽  
Storage Time ◽  
Control Sample ◽  
Double Emulsion ◽  
Colour Variation ◽  
Double Emulsions ◽  
Appreciable Increase ◽  
Different Types ◽  
The Stability

Trans-resveratrol (RSV) needs to be encapsulated to maintain its beneficial properties on the human body. This is due to its extreme photosensitivity, short biological half-life, and easy oxidation. In this study, the use of double emulsions for RSV encapsulation and their further application on functional yoghurts was studied. Different types of yoghurts were prepared: with and without RSV and with two types of volumetric emulsion formulations (20/80 and 30/70). In order to study the influence of the addition of double emulsions to the physical properties of the prepared yoghurts, they were characterised fresh and after a month under storage at 4 °C, in terms of droplet size, morphology, stability, rheology, texturometry, colorimetry, and antioxidant capacity. Results obtained showed that the presence of emulsion in the yoghurts produced a generalised decrease in the predominant droplet size (from 48 µm to 15–25 µm) and an increase in the stability. Additionally, a predominantly elastic character was observed. The firmness values obtained were very similar for all the yoghurts analysed and did not suffer important modifications with time. A slight colour variation was observed with storage time in the control sample, whereas a more notable variation in the case of emulsion yoghurts was observed. An appreciable increase of the antioxidant capacity of the final functional yoghurt (100 g) was observed when it contained 5–8 mg of RSV. Encapsulated RSV added to yoghurts presented a larger protection against RSV oxidation compared with free RSV, presenting a larger antioxidant inhibition after one month of storage. Moreover, the antioxidant capacity of yoghurts with encapsulated RSV was not affected under storage, since slight reductions (3%) were registered after one month of storage at 4 °C.

Studies of Elastomer Oxidation via Thermal Analysis

1999 ◽  
Vol 72 (1) ◽  
pp. 165-173 ◽  
Author(s):  
D. J. Burlett
Keyword(s):  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Oxidation Process ◽  
Industrial Applications ◽  
Scanning Calorimetry ◽  
Thermoanalytical Techniques ◽  
The Stability ◽  
Induction Times ◽  
Oxidation Susceptibility

Abstract Elastomers are used in many industrial applications because of their remarkable toughness and elasticity. However, the source of these properties is also a weakness, in that loss of properties via oxidation is an important factor in their selection. Thermoanalytical techniques, such as differential scanning calorimetry (DSC), provide useful tools for the characterization of the stability of elastomers. DSC can not only be used to determine oxidative induction times under isothermal conditions but can also be used to determine apparent overall activation energies of the oxidation process. An evaluation of these techniques is made and the technique is used to compare the oxidation susceptibility of polybutadienes of different microstructure. The results of these DSC scans are interpreted in terms of the chemistry of the oxidation process using FTIR results.

scholarly journals Preparation and Characterization of Expanded Clay-Paraffin Wax-Geo-Polymer Composite Material

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2191 ◽  
Author(s):  
Ahmed Hassan ◽  
Najif Ismail ◽  
Abdel-Hamid Mourad ◽  
Yasir Rashid ◽  
Mohammad Laghari
Keyword(s):  
Phase Change ◽  
Elevated Temperatures ◽  
Polymer Composite Material ◽  
Temperature History ◽  
Vacuum Impregnation ◽  
Scanning Calorimetry ◽  
Size And Morphology ◽  
The Stability ◽  
Change Material

Paraffin-based phase change material (PCM) is impregnated into the pores of lightweight expanded clay aggregate (LECA) through vacuum impregnation to develop PCM containing macro-capsules of LECA. Three different grades of LECA varying in size and morphology are investigated to host the PCM to determine the impregnation effectiveness, viability for coating, and its stability. The produced LECA-PCM is coated with geopolymer paste (GP) to provide leak proofing during the phase change. The PCM is thermophysically characterized by employing differential scanning calorimetry (DSC) and the temperature history method (THM) to determine the phase transition and the latent heat. The stability of the macro-capsules is determined by weight loss through rapid thermal cycling (RTC) at elevated temperatures. Leakage of the PCM is tested using the diffusion-oozing circle test (DOCT). The results show that the GP coated LECA-PCM macro-capsules achieved 87 wt % impregnation efficiencies and no noticeable loss of PCM, which indicates leak proofing of the developed capsules up to 1000 RTC.

scholarly journals Influence of Hydrophilic Surfactants on the W1–W2 Coalescence in Double Emulsion Systems Investigated by Single Droplet Experiments

2021 ◽  
Vol 5 (2) ◽  
pp. 21
Author(s):  
Nico Leister ◽  
Heike P. Karbstein
Keyword(s):  
Double Emulsion ◽  
Water Phase ◽  
Single Droplet ◽  
Fast Evaluation ◽  
Double Emulsions ◽  
Low Concentrations ◽  
Emulsion Systems ◽  
The Stability ◽  
Single Droplets ◽  
And Diffusion

Double emulsions are a promising formulation for encapsulation and targeted release in pharmaceutics, cosmetics and food. An inner water phase is dispersed in an oil phase, which is again emulsified in a second water phase. The encapsulated inner water phase can be released via diffusion or via coalescence, neither of which is desired during storage but might be intended during application. The two interfaces in a double emulsion are stabilized by a hydrophilic and a lipophilic surfactant, to prevent the coalescence of the outer and the inner emulsion, respectively. This study focuses on the influence of the hydrophilic surfactant on the release of inner water or actives encapsulated therein via coalescence of the inner water droplet with the outer O–W2 interface. Since coalescence and diffusion are difficult to distinguish in double emulsions, single-droplet experiments were used to quantify differences in the stability of inner droplets. Different lipophilic (PGPH and PEG-30 dipolyhydroxylstearate) and hydrophilic surfactants (ethoxylates, SDS and polymeric) were used and resulted in huge differences in stability. A drastic decrease in stability was found for some combinations, while other combinations resulted in inner droplets that could withstand coalescence longer. The destabilization effect of some hydrophilic surfactants depended on their concentration, but was still present at very low concentrations. A huge spread of the coalescence time for multiple determinations was observed for all formulations and the necessary statistical analysis is discussed in this work. The measured stabilities of single droplets are in good accordance with the stability of double emulsions for similar surfactant combinations found in literature. Therefore, single droplet experiments are suggested for a fast evaluation of potentially suitable surfactant combinations for future studies on double-emulsion stability.

scholarly journals Preparation and Characterization of Double-Layered Microcapsules Containing Nano-SiO2

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xue Sun ◽  
Jingcheng Su ◽  
Rui Zhang ◽  
Fangyu Fan
Keyword(s):  
Moisture Content ◽  
Droplet Size ◽  
Gum Arabic ◽  
Core Material ◽  
Wall Material ◽  
Scanning Calorimetry ◽  
Nano Sio2 ◽  
The Core ◽  
The Stability

The double-layered microencapsulation technology has been used in many fields. In this study, the double-layered microencapsulated anthocyanin of Passiflora edulis shells (APESs) was prepared via complex coacervation using gelatin and gum Arabic as the first wall materials (single-layered microcapsules (SMs)) and using gum Arabic containing nano-SiO2 as the second wall material (double-layered microcapsules (DMs)/nano-SiO2) to enhance the stability of the core material. Properties of microcapsules were analyzed on the basis of EE, morphology, scanning electron microscopy (SEM), droplet size, moisture content, and differential scanning calorimetry (DSC). The results showed that the EE values of SMs, DMs, and DMs/nano-SiO2 were 96.12%, 97.24%, and 97.85%, respectively. DMs/nano-SiO2 had the lowest moisture content (2.17%). The average droplet size of DMs/nano-SiO2 (34.93 μm) was higher than those of SMs and DMs. DSC indicated that the melting temperature of DMs/nano-SiO2 was 73.61°C and 45.33°C higher than those of SMs and DMs, respectively. SEM demonstrated that DMs/nano-SiO2 had the smoothest surface compared with the other two kinds of microcapsules. The storage stability of APESs and their microcapsules indicated that the stability of the microcapsules was improved by adding DMs/nano-SiO2 into the wall material of microcapsules. These results indicated double-layered microcapsules containing silica nanoparticles contribute to the stability of the core material.

Preparation and Characterization of Tea Polyphenols/Starch Inclusion Complex

2013 ◽  
Vol 432 ◽  
pp. 413-417 ◽  
Author(s):  
Li Ming Zhang ◽  
Zhi Ying Hu ◽  
Li Hu Yan ◽  
Run Liu Li ◽  
Cheng Wei Cao ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Inclusion Complex ◽  
Inclusion Complexes ◽  
Tea Polyphenols ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
The Stability ◽  
Good Retention

In order to improving the stability and bioavailability of tea polyphenols (TP), the TP/starchinclusion complex(TPSIC) was prepared by adding TP to starch slurry during gelatinization, and its TPreleasing behaviorswas investigated. The formation of inclusion complex was confirmed by powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The TPSIC showed a characteristic of V-type crystallinity and a looser gel matrix. The encapsulation increased the stability of TP and generated a good releasing behavior after enzymatic erosion. The lower releasing rate indicated that the prepared inclusion complexes had good retention ability and effectively reduced the releasing rate of TP. The releasing rate of TPSIC increased with the increase of TP concentration.

scholarly journals Design, Preparation and Thermal Characterization of Polystyrene Composites Reinforced with Novel Three-Cages POSS Molecules

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 2967
Author(s):  
Ignazio Blanco ◽  
Francesco Agatino Bottino ◽  
Gianluca Cicala ◽  
Giulia Ognibene ◽  
Claudio Tosto
Keyword(s):  
1H Nmr Spectroscopy ◽  
In Situ Polymerization ◽  
Thermal Characterization ◽  
Scanning Calorimetry ◽  
Single Cage ◽  
The Stability ◽  
First Time ◽  
Thermal Stability Of

Novel polystyrene (PS)/polyhedral oligomeric silsequioxanes (POSSs) nanocomposites were designed and prepared by in situ polymerization, using, for the first time, three-cage POSS molecules. The synthesized compounds were first characterized by Fourier transform infrared spectroscopy (FTIR) and 1H NMR spectroscopy to verify the obtaining of the designed products before their thermal performance was evaluated and compared with those of pristine PS and the corresponding single-cage POSSs nanocomposites. The thermal behaviour was checked by the means of the differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) was also used to confirm the hypothesis about the dispersion/aggregation of the POSS molecules into the polymer matrix. The parameters chosen to evaluate the thermal stability of the investigated compounds, namely temperature at 5% of mass loss (T5%) and solid residue at 700 °C, showed a significant increase in the stability of the polymers reinforced with the three-cages POSS, in comparison to both PS and single-cage POSS reinforced PSs, which therefore turn out to be promising molecular fillers for nanocomposite production.

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