scholarly journals Thermal Stability of Gel Foams Stabilized by Xanthan Gum, Silica Nanoparticles and Surfactants

Gels ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 179
Author(s):  
Youjie Sheng ◽  
Canbin Yan ◽  
Yang Li ◽  
Yunchuan Peng ◽  
Li Ma ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Surface Activity ◽  
Xanthan Gum ◽  
Foam Stability ◽  
Water Soluble ◽  
Water Soluble Polymer ◽  
Foaming Ability ◽  
Subtle Effect ◽  
Thermal Stability Of ◽  
Foam Drainage

The foams stabilized by nanoparticles (NPs), water-soluble polymers, and surfactants have potential application prospects in the development of new, environmentally friendly firefighting foams. In the present study, a gel foam containing a water-soluble polymer (xanthan gum, XG), hydrophilic silica NPs, hydrocarbon surfactant (SDS), and fluorocarbon surfactant (FS-50) were prepared. The surface activity, conductivity, viscosity, and foaming ability of foam dispersions were characterized. The gel foam stability under a radiation heat source and temperature distribution in the vertical foam layer were evaluated systematically. The results show that the addition of NPs and XG has a significant effect on the foaming ability, viscosity and foam thermal stability, but has a very subtle effect on the conductivity and surface activity. The foaming ability of the FS-50/SDS solution was enhanced by the addition of NPs, but decreased with increasing the XG concentration. The thermal stability of the foams stabilized by SDS/FS-50/NPs/XG increased with the addition of NPs and increasing XG concentration. Foam drainage and coarsening were significantly decelerated by the addition of NPs and XG. The slower foam drainage and coarsening are the main reason for the intensified foam thermal stability. The results obtained from this study can provide guidance for developing new firefighting foams.

On the thermal stability of xanthan gum

Polymer ◽  
1985 ◽  
Vol 26 (10) ◽  
pp. 1549-1553 ◽  
Author(s):  
F. Lambert ◽  
M. Rinaudo
Keyword(s):  
Thermal Stability ◽  
Xanthan Gum ◽  
Thermal Stability Of

scholarly journals Role of Ionic Headgroups on the Thermal, Rheological, and Foaming Properties of Novel Betaine-Based Polyoxyethylene Zwitterionic Surfactants for Enhanced Oil Recovery

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 908 ◽  
Author(s):  
Muhammad Shahzad Kamal ◽  
Syed Muhammad Shakil Hussain ◽  
Lionel Talley Fogang
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Oil Recovery ◽  
Structural Changes ◽  
Foam Stability ◽  
Foaming Properties ◽  
Zwitterionic Surfactants ◽  
Reservoir Conditions ◽  
Thermal Stability Of

Long-term thermal stability of surfactants under harsh reservoir conditions is one of the main challenges for surfactant injection. Most of the commercially available surfactants thermally degrade or precipitate when exposed to high-temperature and high-salinity conditions. In this work, we designed and synthesized three novel betaine-based polyoxyethylene zwitterionic surfactants containing different head groups (carboxybetaine, sulfobetaine, and hydroxysulfobetaine) and bearing an unsaturated tail. The impact of the surfactant head group on the long-term thermal stability, foam stability, and surfactant–polymer interactions were examined. The thermal stability of the surfactants was assessed by monitoring the structural changes when exposed at high temperature (90 °C) for three months using 1H-NMR, 13C-NMR, and FTIR analysis. All surfactants were found thermally stable regardless of the headgroup and no structural changes were evidenced. The surfactant–polymer interactions were dominant in deionized water. However, in seawater, the surfactant addition had no effect on the rheological properties. Similarly, changing the headgroup of polyoxyethylene zwitterionic surfactants had no major effect on the foamability and foam stability. The findings of the present study reveal that the betaine-based polyoxyethylene zwitterionic surfactant can be a good choice for enhanced oil recovery application and the nature of the headgroup has no major impact on the thermal, rheological, and foaming properties of the surfactant in typical harsh reservoir conditions (high salinity, high temperature).

Thermo-physical behaviors of carbon nanofiber reinforced polylactic acid

2013 ◽  
Vol 1505 ◽  
Author(s):  
Ananta Raj Adhikari ◽  
Kamal Sarkar ◽  
Karen Lozano
Keyword(s):  
Thermal Stability ◽  
Polylactic Acid ◽  
Carbon Nanofiber ◽  
Water Soluble ◽  
Steady Increase ◽  
Future Technology ◽  
Large Numbers ◽  
Stage Crystallization ◽  
Thermo Physical Properties ◽  
Thermal Stability Of

ABSTRACT:Studies have demonstrated that the reinforcement of polymeric matrices using nanofiller can results with better thermo-physical properties of polymer. Carbon nanofiber (CNF) is a unique quasi-one dimensional nanostructure with large numbers of edges and defects compared to carbon nanotube (CNT). Further the availability in large quantity along with lower cost makes them an important nanomaterial for future technology. We have previously used CNF in different thermoplastic polymers. In this study CNFs were used with water soluble thermoplastic aliphatic polyster polylactic acid (PLA) and studied their thermal and mechanical properties. Thermal analysis using Thermogravimetric Analysis showed enhanced thermal stability of the polymer at higher nanotube loading (>1 wt%) and decrease of thermal stability at higher loading (>10 wt%). Crystallization thermogram of PLA was modified heavily with the addition of nanofibers changing clearly from one stage to two stage crystallization. In addition, CNF facilitates the crystallization of PLA resulting in an increase of its crystallization. The mechanical testing showed the steady increase of modulus of the composites with the nanofiber content within the range of study which can be regarded as due to the change in interface property of the composites.

Chemical modification results in hyperactivation and thermostabilization ofFusarium solaniglucoamylase

2007 ◽  
Vol 53 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Haq Nawaz Bhatti ◽  
M. Hamid Rashid ◽  
Muhammad Asgher ◽  
Rakhshanda Nawaz ◽  
A.M. Khalid ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Chemical Modification ◽  
Soluble Starch ◽  
Water Soluble ◽  
Chemically Modified ◽  
Free Energy Of Activation ◽  
Enthalpy Of Activation ◽  
Specificity Constant ◽  
Modified Forms ◽  
Thermal Stability Of

Chemical modification of carboxyl groups of glucoamylase from a mesophilic fungus, Fusarium solani , was carried out using ethylenediamine as nucleophile in the presence of water-soluble 1-ethyl-3(3-dimethylaminopropyl)carbodiimide. Modification brought about a dramatic enhancement of catalytic activity and thermal stability of glucoamylase. Temperature and pH optima of ethylenediamine-coupled glucoamylase (ECG) increased as compared with those of native enzyme. The specificity constant (kcat/Km) of native, ECG-2, ECG-11, and ECG-17 was 136, 173, 225, and 170, respectively, at 55 °C. The enthalpy of activation (ΔH*) and free energy of activation (ΔG*) for soluble starch hydrolysis were lower for the chemically modified forms. All of the modified forms werestable at higher temperatures and possessed high ΔG* against thermal unfolding. The effects of α-chymotrypsin and subtilisin on the modified forms were activating as compared with native. Moreover, denaturation of ECG-2, ECG-11, and ECG-17 in urea at 4 mol·L–1also showed an activation trend. A possible explanation for the thermal denaturation of native and increased thermal stability of ECG-2, ECG-11, and ECG-17 at higher temperatures is also discussed.

Preparation and properties of melamine formaldehyde resin modified by functionalized nano-SiO2 and polyvinyl alcohol

2020 ◽  
pp. 096739112090354
Author(s):  
Zhu Xiong ◽  
Ning Chen ◽  
Qi Wang
Keyword(s):  
Thermal Stability ◽  
Impact Strength ◽  
Polyvinyl Alcohol ◽  
Flame Retardant ◽  
Flame Retardancy ◽  
Water Soluble ◽  
Hot Water ◽  
Formaldehyde Resin ◽  
Melamine Formaldehyde ◽  
Water Soluble Polymer

Melamine formaldehyde (MF) resin is a thermosetting polymer with superior flame retardancy and high thermal stability and is widely used in fire-retardant coatings, flame-retardant sheets, heat-resistant filter materials, and so on. However, its further application is restricted by its extreme brittleness and poor impact strength. In this article, polyvinyl alcohol (PVA), a water-soluble polymer with high toughness and elasticity, which can be well blended with MF prepolymer in hot water, was used to improve the toughness of MF resin. The nano-silicon dioxide (SiO2) particles modified by KH-550 were used to improve the compatibility between MF prepolymer and PVA. Moreover, the modified nano-SiO2 can simultaneously enhance the toughness and impact the strength of MF resin. The interaction of components, fractography, thermal stability, flame retardancy, and mechanical properties of the modified MF resin was studied systematically. Fourier transform infrared results indicate that KH-550 was successfully grafted onto the surface of nano-SiO2. The grafted nano-SiO2 shows better dispersion in the matrix than the unmodified one, furthermore improving the compatibility and interface adhesion between MF and PVA. When PVA content is 20%, the obtained material has good thermal stability ( T max > 350°C), flame-retardant properties (UL-94 V-0 rating and limited oxygen index = 42%), and toughness (elongation at break > 20% and unnotched impact strength > 13 kJ m−2).

scholarly journals Thermal stability of amorphous sugar matrix, dried from methanol, as an amorphous solid dispersion carrier

2018 ◽  
Author(s):  
Koreyoshi Imamura ◽  
K. Takeda ◽  
K. Yamamoto ◽  
H. Imanaka ◽  
N. Ishida
Keyword(s):  
Thermal Stability ◽  
Solid Dispersion ◽  
Amorphous Solid ◽  
Water Soluble ◽  
Solid Matrix ◽  
Amorphous Solid Dispersion ◽  
Solid Mixture ◽  
Soluble Solid ◽  
Dispersion Technique ◽  
Thermal Stability Of

Developing a technique to disperse hydrophobic ingredients homogeneously in a water-soluble solid matrix (solid dispersion) is one of the topics that have been extensively investigated in the pharmaceutical and food industries. Recently, we have devised a novel solid dispersion technique (surfactant-free solid dispersion), in which a preliminarily amorphized sugar was dissolved in an organic media containing hydrophobic component, without using any surface active substances, and then vacuum dried into the amorphous solid mixture [Food Chem., 197 (2016) 1136; Mol. Pharm., 14 (2017) 791]. In this study, the physicochemical properties, especially thermal stability of the surfactant-free amorphous solid dispersion, were investigated. keywords: solid dispersion; amorphous sugar; surfactant-free; vacuum drying; glass transition temperature

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