scholarly journals One-Shot Preparation of Polybasic Ternary Hybrid Cryogels Consisting of Halloysite Nanotubes and Tertiary Amine Functional Groups: An Efficient and Convenient Way by Freezing-Induced Gelation

Gels ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 16
Author(s):  
Nur Sena Okten Besli ◽  
Nermin Orakdogen
Keyword(s):  
Functional Groups ◽  
Tertiary Amine ◽  
Current System ◽  
Halloysite Nanotubes ◽  
Mechanical Tests ◽  
Significant Loss ◽  
Temperature Sensitive ◽  
Positive Temperature ◽  
Swelling Ratio ◽  
Hybrid Gels

A convenient method for the preparation of polybasic ternary hybrid cryogels consisting of Halloysite nanotubes (HNTs) and tertiary amine functional groups by freezing-induced gelation is proposed. Ternary hybrid gels were produced via one-shot radical terpolymerization of 2-hydroxyethyl methacrylate (HEMA), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS), and DEAEMA in the presence of HNTs. The equilibrium swelling in various swelling media and the mechanical properties of the produced ternary hybrid gels were analyzed to investigate their network structure and determine their final performance. The swelling ratio of HNT-free gels was significantly higher than the ternary hybrid gels composed of high amount of HNTs. The addition of HNTs to terpolymer network did not suppress pH- and temperature-sensitive behavior. While DEAEMA groups were effective for pH-sensitive swelling, it was determined that both HEMA and DEAEMA groups were effective in temperature-sensitive swelling. Ternary hybrid gels simultaneously demonstrated both negative and positive temperature-responsive swelling behavior. The swelling ratio changed considerably according to swelling temperature. Both DEAEMA and HEMA monomers in terpolymer structure were dominant in temperature-sensitive swelling. Mechanical tests in compression of both as-prepared and swollen-state demonstrated that strength and modulus of hybrid cryogels significantly increased with addition of HNTs without significant loss of mechanical strength. Ultimately, the results of the current system can benefit characterization with analysis tools for the application of innovative materials.

scholarly journals PENGARUH FLOURIDE TERHADAP SIFAT MEKANIK GIGI TIRUAN BERBAHAN DASAR LIMBAH CANGKANG TELUR AYAM

2019 ◽  
Vol 4 (1) ◽  
pp. 72-77
Author(s):  
Baiq R. S. Yusuf ◽  
Siti Alaa ◽  
Dian W. Kurniawidi ◽  
Susi Rahayu
Keyword(s):  
Functional Groups ◽  
Calcium Oxide ◽  
Mechanical Tests ◽  
Precipitation Method ◽  
Oxide Content ◽  
Distilled Water ◽  
Minimum Standard ◽  
Fluoride Toothpaste ◽  
Egg Shells

The fabrication of dentures from the eggshell has been done using the precipitation method. FTIR and AAS tests were carried out to determine the functional groups and calcium oxide content in egg shells. From the AAS results, the CaO value is 58.33% which is much greater than the minimum standard CaO in dentures. Mechanical tests were carried out on dentures treatment with immersion into distilled water and the results were compared if immersion using fluoride toothpaste. It was found that immersion with fluoride toothpaste can increase the elasticity of dentures by more than 100%.

Enhancement of Mechanical Properties of ABS/PC-HNT Nano Composites

2018 ◽  
Vol 24 (8) ◽  
pp. 6000-6003
Author(s):  
Y. Narendra Babu ◽  
M. Venkateswara Rao ◽  
A. Gopala Krishna
Keyword(s):  
Mechanical Properties ◽  
Matrix Material ◽  
Acrylonitrile Butadiene Styrene ◽  
Halloysite Nanotubes ◽  
Mechanical Tests ◽  
Screw Extruder ◽  
Nano Composite ◽  
Melt Compounding ◽  
Twin Screw ◽  
Butadiene Styrene

The objective of this paper is to experimentally study tensile strength, Impact strength, Flexural strength and Wear Characteristics of the Nano tubular material Halloysite Nanotubes (HNT) into ABS/PC blend with ABS and PC compositions in the ratio 40/60. We have fabricated the Thermoplastic Nanocomposites specimens as per ASTM standards, with the Acrylonitrile Butadiene Styrene (ABS) and Polycarbonate (PC) blend as matrix material and with 1%, 2%, 3%, 4%, 5% and 6% HNT reinforcement material using Co–Rotating Intermeshing Twin Screw Extruder by Melt Compounding. Mechanical Tests were conducted and results were compared with the original ABS/PC blend. Effects of Halloysite Nanotubes reinforcement percentage were discussed in detail. The obtained results suggested that ABS/PC (40/60) blend with 4% reinforcement of Halloysite Nanotubes executed better mechanical properties. SEM is used to study the failure mechanism of the proposed Nano composite.

scholarly journals Hysteresis Effects During the Phase Transition in Solutions of Temperature Sensitive Polymers

2017 ◽  
Vol 19 (1) ◽  
pp. 41 ◽  
Author(s):  
I.E. Suleimenov ◽  
O. Guven ◽  
G.A. Mun ◽  
Ch. Uzun ◽  
O.A. Gabrielyan ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Functional Groups ◽  
Hydrophobic Interactions ◽  
Practical Interest ◽  
Temperature Sensitive ◽  
Electronic Systems ◽  
Sharp Change ◽  
Fluid Properties ◽  
Thermodynamic Variables ◽  
Hysteresis Phenomena

It is demonstrated, for the first time,that well-known phase transitions induced by changes in temperature in solutions of polymers containing both hydrophilic and hydrophobic functional groups could be followed by noticeable hysteresis effects. A<br />well-known phase transitions accompanied by a sharp change in fluid properties, in particular its optical density can be induced by many external influences, including temperature changes occurring in the solutions of polymers containing both<br />hydrophilic and hydrophobic functional groups. Since intensification subsequent hydrophobic interactions, leading to loss of solubility of the polymer molecules, resulting, in particular, a significant increase in the turbidity of the medium and are accompanied by a pronounced hysteresis phenomena. Hysteresis phenomena in the processes of molecular-scale play an important theoretical and practical interest in linkage with the development of advanced nano-level technology. In particular, the issue of the development of molecular "trigger" switches, and other analog electronic systems, implemented on submolecular level was actively discussed. In fact, under the same physical conditions of the environment of macromolecules system can be in two different states, which resolves the issue of programming such molecules. State of these polymers depends on their way of formation and thermodynamic variables. Observed effect could be utilized directly for information recording into the structure on the basis of stimulus-sensitive macromolecular chains. In fact, it is a first step towards creating memory of quasi-biological elements.

Halloysite Nanotubes Functionalized Sulfonic Acid: Synthesis, Spectroscopic Characterization, Computational Studies and Application for the Synthesis of 1,4-Dihydropyridines

2021 ◽  
Vol 18 ◽  
Author(s):  
Princy Gupta ◽  
Nayan Prakash ◽  
Yogeshwar Ramawat ◽  
Palvi Rajput ◽  
Amir Fayaz ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Sulfonic Acid ◽  
Spectroscopic Characterization ◽  
Acid Synthesis ◽  
Halloysite Nanotubes ◽  
Spectroscopic Studies ◽  
Significant Loss ◽  
One Pot ◽  
Solvent Free Conditions ◽  
Chemical Studies

: Naturally occurring clay halloysite is used to synthesize novel halloysite functionalized sulfonic acid in two steps; functionalization followed by oxidation and its catalytic activity is estimated for one-pot synthesis of Hantzsch 1,4-dihydropyridines under green solvent-free conditions. Spectroscopic studies such as FTIR, TGA, elemental analysis and first-principles based quantum chemical studies are used to characterize the catalyst. Recyclability without significant loss of catalytic activity is observed for several runs.

A Review on Effect of Elevate Temperature on Properties of Self-Compacting Concrete Containing Steel Fiber, Glass Fiber and Polypropylene Fiber

2020 ◽  
Vol 3 (10) ◽  
pp. 9-15
Author(s):  
Vivek Gupta ◽  
Gokulnath Venkadachalam
Keyword(s):  
High Temperatures ◽  
Glass Fibre ◽  
Steel Fibre ◽  
Significant Loss ◽  
Polypropylene Fibre ◽  
Temperature Sensitive ◽  
Fine Aggregate ◽  
Self Compacting Concrete ◽  
Explosive Spalling ◽  
Fibre Glass

This paper presents an investigation into the efficiency of temperature-sensitive self-compacting concrete. Reviewing on self-compacted concrete, steel fibre, glass fibre, Polypropylene fibre. To this end, adding fibres (steel fibre, glass fibre, Polypropylene) content 1.2% for mixture of concrete material. When the cube samples were 28 days old. They have been heated to high temperatures. Each samples were heated to different temperatures for each concrete mixture (0ºC,100C, 200ºC). Then, Tests for weight loss and compressive strength were performed. The Observations of surface cracks were made after exposure to high temperatures. A significant loss of strength up to 30-40% for all concretes after 300ºC was observed, especially for concrete containing Polypropylene fibre, glass fibre, steel fibre. The fibres reduced the risk of explosive spalling and prevented it. Based on the results of the study, the output of fine aggregate concrete can be inferred.

scholarly journals Northern Hemisphere temperature patterns in the last 12 centuries

2012 ◽  
Vol 8 (1) ◽  
pp. 227-249 ◽  
Author(s):  
F. C. Ljungqvist ◽  
P. J. Krusic ◽  
G. Brattström ◽  
H. S. Sundqvist
Keyword(s):  
20Th Century ◽  
Northern Hemisphere ◽  
Temperature Sensitive ◽  
Large Network ◽  
Positive Temperature ◽  
Northern Hemisphere Temperature ◽  
The Past ◽  
Proxy Records ◽  
Hemisphere Temperature ◽  
Spatio Temporal

Abstract. We analyse the spatio-temporal patterns of temperature variability over Northern Hemisphere land areas, on centennial time-scales, for the last 12 centuries using an unprecedentedly large network of temperature-sensitive proxy records. Geographically widespread positive temperature anomalies are observed from the 9th to 11th centuries, similar in extent and magnitude to the 20th century mean. A dominance of widespread negative anomalies is observed from the 16th to 18th centuries. Though we find the amplitude and spatial extent of the 20th century warming is within the range of natural variability over the last 12 centuries, we also find that the rate of warming from the 19th to the 20th century is unprecedented in the context of the last 1200 yr. The positive Northern Hemisphere temperature change from the 19th to the 20th century is clearly the largest between any two consecutive centuries in the past 12 centuries. These results remain robust even after removing a significant number of proxies in various tests of robustness showing that the choice of proxies has no particular influence on the overall conclusions of this study.

scholarly journals A decrease in taxonomic and functional diversity of dung beetles impacts the ecosystem function of manure removal in altered subtropical habitats

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0244783
Author(s):  
Rodrigo Sarmiento-Garcés ◽  
Malva Isabel Medina Hernández
Keyword(s):  
Environmental Factors ◽  
Functional Groups ◽  
Functional Diversity ◽  
Removal Rate ◽  
Significant Loss ◽  
Dung Beetles ◽  
Habitat Destruction ◽  
Ecosystem Functions ◽  
Functional Richness ◽  
Soil Temperatures

The loss of biodiversity—caused mainly by habitat destruction—is one of the environmental problems with major repercussions on ecosystem functioning. Nevertheless, our understanding of the functional consequences of habitat changes on the communities and ecosystems remains limited to a small number of case studies. We evaluated the change in taxonomic and functional diversity of copro-necrophagous beetles (Scarabaeinae) and their relationship with the varying environmental factors present in four habitats with different degrees of disturbance. Furthermore, we evaluated how changes in taxonomic and functional diversity affect the rates of excrement removal. The collections were carried out at four locations in the state of Santa Catarina, Southern Brazil, on natural systems with different degrees of disturbances (forests in advanced and initial succession) and agroecosystems (silviculture and pastures dedicated to livestock). We collected a total of 1266 dung beetles distributed in 35 species and classified into 11 functional groups. The taxonomic and functional diversity analyses showed that habitats that still maintain an arboreal stratum do not present differences between them, in contrast to habitats dedicated to livestock where there was a significant loss of species and functional groups. The distance between the trees, as well as the air and soil temperatures were determining factors in the selection of species and functional groups. Some of these environmental factors explain the differences in functional traits, represented as varying abundances of the species found. The rates of manure removal from the ecosystem were positively correlated to taxonomic and functional richness as well as biomass of beetles. Thus, we can conclude that habitats with tree strata have the capacity to preserve a larger proportion of the regional set of species as well as the important ones, while preserving the taxonomic and functional diversity and the ecosystem functions, such as the excrement removal rate.

Sign in / Sign up

Export Citation Format

Share Document