Structural evaluation of percolating, self-healing polyurethane–polycaprolactone blends doped with metallic, ferromagnetic, and modified graphene fillers

2020 ◽  
pp. 096739112092382
Author(s):  
D Wlodarczyk ◽  
I Zmuda-Trzebiatowska ◽  
J Karczewski ◽  
M Lubinska-Szczygel ◽  
M Urban ◽  
...  
Keyword(s):  
Structural Changes ◽  
Organic Coating ◽  
Spectroscopic Techniques ◽  
Self Healing ◽  
Metallic Structures ◽  
Structural Evaluation ◽  
Strategic Value ◽  
Reduced Graphene ◽  
Modified Graphene ◽  
Conductive Properties

Composites with differently shaped micro- and nanofillers show various, unique thermal, and physicochemical properties when mixed with carefully chosen polymer matrix. Selected composition holds strategic value in achieving desired properties that is biodegradability, thermoelectric conductivity, and shape memory for organic coating. The main aim of this work is to briefly examine structural changes after reaching percolation threshold and activating healing abilities within exploited (8–2 wt ratio) polyurethane–polycaprolactone thin films mixed up with different types of metallic and ferromagnetic microfillers. They, with applicable dosages of reduced graphene oxide nanoparticles, should enhance materials’ mechanical and conductive properties. Microscopic and spectroscopic techniques accompanied by extensive thermal analysis have been chosen to provide useful information about local changes in surface structure and morphology. Moreover, pristine, percolating surface with inner-formed, metallic structures shows moderate conducting properties within exploited materials which unfortunately diminish after thermal healing stimulus is being applied. This statement is supported by observing the coverage of regional defects and nearby pores with a concise, uniform layer of blend having different PU:PCL ratio. Including the additional fact that apparent filler migration is changing local dopant composition brings up an assumption that both phenomena have negative synergy effect on each other.

Influence of Ascorbic Acid on the Structure and Function of Alpha-2- macroglobulin: Investigations using Spectroscopic and Thermodynamic Techniques

2020 ◽  
Vol 27 (3) ◽  
pp. 201-209
Author(s):  
Syed Saqib Ali ◽  
Mohammad Khalid Zia ◽  
Tooba Siddiqui ◽  
Haseeb Ahsan ◽  
Fahim Halim Khan
Keyword(s):  
Ascorbic Acid ◽  
Conformational Changes ◽  
Structural Changes ◽  
The Body ◽  
Titration Calorimetry ◽  
Spectroscopic Techniques ◽  
Human Beings ◽  
Plasma Ascorbic Acid ◽  
Dietary Antioxidant ◽  
And Function

Background: Ascorbic acid is a classic dietary antioxidant which plays an important role in the body of human beings. It is commonly found in various foods as well as taken as dietary supplement. Objective: The plasma ascorbic acid concentration may range from low, as in chronic or acute oxidative stress to high if delivered intravenously during cancer treatment. Sheep alpha-2- macroglobulin (α2M), a human α2M homologue is a large tetrameric glycoprotein of 630 kDa with antiproteinase activity, found in sheep’s blood. Methods: In the present study, the interaction of ascorbic acid with alpha-2-macroglobulin was explored in the presence of visible light by utilizing various spectroscopic techniques and isothermal titration calorimetry (ITC). Results: UV-vis and fluorescence spectroscopy suggests the formation of a complex between ascorbic acid and α2M apparent by increased absorbance and decreased fluorescence. Secondary structural changes in the α2M were investigated by CD and FT-IR spectroscopy. Our findings suggest the induction of subtle conformational changes in α2M induced by ascorbic acid. Thermodynamics signatures of ascorbic acid and α2M interaction indicate that the binding is an enthalpy-driven process. Conclusion: It is possible that ascorbic acid binds and compromises antiproteinase activity of α2M by inducing changes in the secondary structure of the protein.

Synthesis and Characterization of Reduced Graphene Oxide

2013 ◽  
Vol 678 ◽  
pp. 56-60 ◽  
Author(s):  
Cherukutty Ramakrishnan Minitha ◽  
Ramasamy Thangavelu Rajendrakumar
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Graphite Oxide ◽  
High Performance ◽  
Structural Changes ◽  
Epoxy Group ◽  
Xrd Analysis ◽  
Si Substrates ◽  
Reduced Graphene ◽  
Reduced Graphite Oxide

Reduced graphene oxide is an excellent candidate for various electronic devices such as high performance gas sensors. In this work Graphene oxide was prepared by oxidizing graphite to form graphite oxide. From XRD analysis the peak around 11.5o confirmed that the oxygen was intercalated into graphite. By using hydrazine hydrate, the epoxy group in graphite oxide was reduced then the solution of reduced graphite oxide (rGO) is exfoliated. Raman spectrum of rGO contains both G band (1580 cm-1), D band (1350 cm-1). The remarkable structural changes reveals that reduction of graphene oxide from the values of ID/IG ratio that increase from 0.727 (GO) to 1.414 (rGO). The exfoliated reduced graphite oxide solution is spin coated on to the SiO2/Si substrates.

scholarly journals Preparation and Properties of Self-Healing and Self-Lubricating Epoxy Coatings with Polyurethane Microcapsules Containing Bifunctional Linseed Oil

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1578 ◽  
Author(s):  
Haijuan Yang ◽  
Qiufeng Mo ◽  
Weizhou Li ◽  
Fengmei Gu
Keyword(s):  
Interfacial Polymerization ◽  
Electrochemical Impedance ◽  
Linseed Oil ◽  
Salt Spray ◽  
Average Diameter ◽  
Organic Coating ◽  
Epoxy Coating ◽  
The Self ◽  
Self Healing ◽  
Pure Epoxy

An organic coating is commonly used to protect metal from corrosion, but it is prone to failure due to microcracks generated by internal stress and external mechanical action. The self-healing and self-lubricating achieved in the coating is novel, which allows an extension of life by providing resistance to damage and repair after damage. In this study, a new approach to microencapsulating bifunctional linseed oil with polyurethane shell by interfacial polymerization. Moreover, the self-healing and self-lubricating coatings with different concentrations of microcapsules were developed. The well-dispersed microcapsules showed a regular spherical morphology with an average diameter of ~64.9 μm and a core content of 74.0 wt.%. The results of the salt spray test demonstrated that coatings containing microcapsules still possess anticorrosion, which is improved with the increase of microcapsules content, after being scratched. The results of electrochemical impedance spectroscopy showed a |Z|f=0.01Hz value of 104 Ω·cm2 for pure epoxy coating after being immersed for 3 days, whereas the coating with 20 wt.% microcapsules was the highest, 1010 Ω·cm2. The results of friction wear showed that the tribological performance of the coating was enhanced greatly as microcapsule concentration reached 10 wt.% or more, which showed a 86.8% or more reduction in the friction coefficient compared to the pure epoxy coating. These results indicated that the coatings containing microcapsules exhibited excellent self-healing and self-lubricating properties, which are positively correlated with microcapsules content.

scholarly journals Investigation of the Effect of Sodium Selenate on Acetylcholinesterase Activity under Extremely Low Frequency Electromagnetic Field

2012 ◽  
Vol 4 (1) ◽  
Author(s):  
Ezzatollah Fathi ◽  
Raheleh Farahzadi
Keyword(s):  
Electromagnetic Field ◽  
Structural Changes ◽  
Tertiary Structure ◽  
Low Frequency ◽  
Acetylcholinesterase Activity ◽  
The Elderly ◽  
Skin Aging ◽  
Sodium Selenate ◽  
Spectroscopic Techniques ◽  
Extremely Low Frequency

Acetylcholinestrase (AChE EC 3.1.1.7) is one of the most important enzymes in nervous system, which plays a role in Alzheimer’s disease. Selenium is a vital micronutrient and many investigations have been performed about the physiological, biochemical and behavioral effects of this element, such as postponing the Alzheimer's symptoms in the elderly and delaying the initiation signs of skin aging. Recent studies have shown that this element protects various enzymes against the toxicity caused by heavy metals such as; Pb, Al, Cu and Cd. AChE activity is altered under the influence of extremely low frequency electromagnetic field (ELF-EMF). In this study, the effects of ELF-EMF, with 0.3 mT field intensity and 50, 100, 217 Hz frequencies, were investigated on the AChE, in the presence of different concentrations of sodium selenate, using UV-Visible, fluorescence and circular dichroism spectroscopic techniques. The results demonstrated that the enzyme activity declined by increasing the frequency and the amount of sodium selenate. Also, significant structural changes occurred in the secondary and tertiary structures of AChE. Our results showed that with increasing the concentration of sodium selenate transition from α-helix to β-structure was appeared in the presence of ELF-EMF. In conclusion, according to changes observed in the secondary and tertiary structure of enzyme, it is proposed that these fields are able to affect the structure and dynamics of the active site gorge of AChE.

scholarly journals Three-Dimensional Heterostructured Reduced Graphene Oxide-Hexagonal Boron Nitride-Stacking Material for Silicone Thermal Grease with Enhanced Thermally Conductive Properties

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 938 ◽  
Author(s):  
Weijie Liang ◽  
Xin Ge ◽  
Jianfang Ge ◽  
Tiehu Li ◽  
Tingkai Zhao ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Boron Nitride ◽  
Reduced Graphene Oxide ◽  
Hexagonal Boron Nitride ◽  
Three Dimensional ◽  
Thermal Interface Materials ◽  
Reduced Graphene ◽  
Thermally Conductive ◽  
Thermal Grease ◽  
Conductive Properties

The thermally conductive properties of silicone thermal grease enhanced by hexagonal boron nitride (hBN) nanosheets as a filler are relevant to the field of lightweight polymer-based thermal interface materials. However, the enhancements are restricted by the amount of hBN nanosheets added, owing to a dramatic increase in the viscosity of silicone thermal grease. To this end, a rational structural design of the filler is needed to ensure the viable development of the composite material. Using reduced graphene oxide (RGO) as substrate, three-dimensional (3D) heterostructured reduced graphene oxide-hexagonal boron nitride (RGO-hBN)-stacking material was constructed by self-assembly of hBN nanosheets on the surface of RGO with the assistance of binder for silicone thermal grease. Compared with hBN nanosheets, 3D RGO-hBN more effectively improves the thermally conductive properties of silicone thermal grease, which is attributed to the introduction of graphene and its phonon-matching structural characteristics. RGO-hBN/silicone thermal grease with lower viscosity exhibits higher thermal conductivity, lower thermal resistance and better thermal management capability than those of hBN/silicone thermal grease at the same filler content. It is feasible to develop polymer-based thermal interface materials with good thermal transport performance for heat removal of modern electronics utilising graphene-supported hBN as the filler at low loading levels.

Self-Healing Coatings to Mitigate Post-Impact Corrosion

CORROSION ◽  
10.5006/2382 ◽  
2017 ◽  
Vol 73 (9) ◽  
pp. 1091-1097 ◽  
Author(s):  
Atousa Plaseied ◽  
Allen Skaja ◽  
Ramanathan Lalgudi ◽  
Christine Henderson
Keyword(s):  
Service Life ◽  
Exposure Period ◽  
Metal Substrate ◽  
The Self ◽  
Coating System ◽  
Self Healing ◽  
Polymeric Coatings ◽  
Metallic Structures ◽  
Post Impact ◽  
Salt Fog

Self-healing polymeric coatings have offered tremendous potential for repairing damage and extending the service life and safety of metallic structures. There have been many challenges associated with the catalyst activated version of the self-healing oligomer filled microcapsule coating additives (or microbeads) technology, but a non-catalyst version appears more promising. The objective of this study was to identify the effect of self-healing coatings in an epoxy coating system containing the non-catalyst microbeads on post-impact corrosion mitigation of water infrastructure. Experimental results showed that coatings containing microbeads did not fully prevent corrosion of the post-impact exposed metal substrate over the exposure period for this study, especially in salt fog and immersion conditions. However, this coating showed less coating degradation compared to the coating without the presence of microbeads.

scholarly journals Structural Evaluation on Sugarcane Bagasse Treated Using Sodium and Calcium Hydroxide

2019 ◽  
Vol 130 ◽  
pp. 01018
Author(s):  
Juliana Anggono ◽  
Hariyati Purwaningsih ◽  
Suwandi Sugondo ◽  
Steven Henrico ◽  
Sanjaya Sewucipto ◽  
...  
Keyword(s):  
Weight Loss ◽  
Calcium Hydroxide ◽  
Structural Changes ◽  
Natural Fiber ◽  
Treatment Time ◽  
Alkali Treatment ◽  
Natural Fibers ◽  
Additional Treatment ◽  
Structural Evaluation ◽  
By Products

Greater interest in recent years to the increase demand in using natural fiber reinforcement of polymers is to comply with the increasing stringent international protocols related to climate change and environmental awareness. Many studies have reported the development of renewable and biodegradable agricultural by-products as reinforcement fibers for biocomposites. One of the essential factors in producing strong biocomposites is the properties prepared from the natural fibers which results from the alkalitreatment given. This research aims to evaluate the effect of different treatment duration on structural changes on sugarcane after alkali treatment using sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2) solutions. Calcium hydroxide was used as comparative solution in search for milder and more environmental friendly alkali solution as an alternative solution of NaOH. Fourier Transform Infrared (FTIR) confirmed the major removal of lignin and minor of hemicellulose. It shows that the structure did not change considerably with the additional treatment time. The weight loss measurement after each treatmentshows a higher weight loss with the treatment with NaOH (40.5 % to 57.75 %) than the weight loss after Ca(OH)2 treatment (25 % to 46 %). Scanning electron microscope (SEM) observed the morphology changes onthe fiber from both treatments.

High strength zwitterionic nano-micelle hydrogels with superior self-healing, adhesive and ion conductive properties

2020 ◽  
Vol 133 ◽  
pp. 109761
Author(s):  
Yuanna Sun ◽  
Shuaishuai Lu ◽  
Qingshan Li ◽  
Yanwei Ren ◽  
Yuanqing Ding ◽  
...  
Keyword(s):  
High Strength ◽  
Self Healing ◽  
Conductive Properties
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