Characterization of Red Seaweed Extracts Treated by Water, Acid and Alkaline Solutions

2018 ◽  
Vol 14 (4) ◽  
Author(s):  
Ahmed Al-Alawi ◽  
Pothiraj Chitra ◽  
Abdullah Al-Mamun ◽  
Insaaf Al-Marhubi ◽  
Mohammad Shafiur Rahman
Keyword(s):  
High Performance ◽  
Thermal Characteristics ◽  
Bimodal Distribution ◽  
Ester Group ◽  
Alkaline Solutions ◽  
Molecular Characteristics ◽  
Red Seaweed ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry

Abstract Seaweed contained health functional polysaccharides and polyphenols. Five extracts were prepared from red seaweed Melanothamnus somalensis; two of these were aqueous at 20°C (F1) and 70°C (F2), followed by acid (F3), alkali (F4) and acid-washed (F5) treatments. Molecular characteristics of extracts were measured by high-performance liquid chromatography and Fourier transform infrared (FTIR) analyses. Health functionality was determined by sulfate and polyphenol contents, and thermal characteristics were determined by modulated differential scanning calorimetry. Extract F3 contained the highest levels of sulfate followed by F2, F1, F4 and F5, respectively. Similarly, F3 contained the highest polyphenol followed by F4, F2, F1 and F5, respectively. Molecular weight distribution of F1 showed wider distribution of sizes (MW: 1.0 × 103 – 3.0 × 107), and F5 showed a sharp peak (MW: 3.1 × 103); whereas F2, F3 and F4 indicated bimodal distribution. FTIR indicated that all fractions contained agar except F5 and sulfate ester group was attached to carbon 6 of the saccharide.

scholarly journals Synthesis and Polymerization Kinetics of Rigid Tricyanate Ester

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1686
Author(s):  
Andrey Galukhin ◽  
Roman Nosov ◽  
Ilya Nikolaev ◽  
Elena Melnikova ◽  
Daut Islamov ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Single Step ◽  
Polymerization Kinetics ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Polymerization Product ◽  
The One ◽  
Kinetics Of

A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the polymerization kinetics. A transition of polymerization from a kinetic- to a diffusion-controlled regime is detected. Kinetic analysis is performed by combining isoconversional and model-based computations. It demonstrates that polymerization in the kinetically controlled regime of the present monomer can be described as a quasi-single-step, auto-catalytic, process. The diffusion contribution is parameterized by the Fournier model. Kinetic analysis is complemented by characterization of thermal properties of the corresponding polymerization product by means of thermogravimetric and thermomechanical analyses. Overall, the obtained experimental results are consistent with our hypothesis about the relation between the rigidity and functionality of the cyanate ester monomer, on the one hand, and its reactivity and glass transition temperature of the corresponding polymer, on the other hand.

Thermal Characterization of Non-Isolated DC to DC Convertor

2011 ◽  
Author(s):  
Shiladitya Chakravorty ◽  
Bahgat Sammakia ◽  
Varaprasad Calmidi
Keyword(s):  
Power Dissipation ◽  
High Performance ◽  
Field Effect Transistors ◽  
Thermal Characteristics ◽  
Thermal Characterization ◽  
Input Voltage ◽  
Thermal Design ◽  
Power Module ◽  
Improved Performance

Improved performance of semiconductor devices in recent years has resulted in consequent increase in power dissipation. Hence thermal characterization of components becomes important from an overall thermal design perspective of the system. This study looks at a high performance non-isolated point of load power module (a DC to DC converter) meant for advanced computing and server applications. Thermal characteristics of the module were experimentally analyzed by placing the power module on a bare test board (with no insulation) inside a wind tunnel with thermocouples attached to it. There were three devices on this module that dissipate power. There were two FETs (Field Effect Transistors) and an inductor which can be considered as sources. The consolidated power dissipation from the module was calculated by measuring the input voltage and input current while keeping the output voltage and current constant. Temperatures at various points on the module and the test card were recorded for different air flow velocities and overall power dissipation. Subsequently this set up was numerically analyzed using a commercially available computational fluid dynamics (CFD) code with the objective of comparing the results with experimental data previously obtained.

scholarly journals Plastic Bottle Cap Recycling—Characterization of Recyclate Composition and Opportunities for Design for Circularity

2020 ◽  
Vol 12 (24) ◽  
pp. 10378
Author(s):  
Markus Gall ◽  
Andrea Schweighuber ◽  
Wolfgang Buchberger ◽  
Reinhold W. Lang
Keyword(s):  
High Performance ◽  
Regulatory Requirements ◽  
Scanning Calorimetry ◽  
Comprehensive Strategy ◽  
Polymer Resin ◽  
Plastic Bottle ◽  
Use Phase ◽  
Slip Agent ◽  
Beverage Packaging

In line with efforts to create a circular economy of plastics, recent EU legislation is strengthening plastic bottle recycling by ambitious separate collection targets and mandatory recycled content obligations. Furthermore, explicit design requirements on the caps of bottles and composite beverage packaging have been introduced. These caps are typically made of polyethylene or polypropylene and often contain additives such as slip agents and anti-statics. Commercially available bottle cap recyclates (BCRs) as well as specifically formulated model compounds were analyzed in terms of composition by means of infrared spectroscopy, differential scanning calorimetry, and high-performance liquid chromatography. Their composition was found to be heterogeneous due to polyolefin cross-contamination, directly reflecting the diversity of cap materials present in the market. Slip agent legacy additives originating from the initial use phase were found and quantified in both commercial and model cap recyclates. This highlights the opportunity for redesigning plastic bottle caps not only in response to regulatory requirements, but to pursue a more comprehensive strategy of product design for circularity. By including considerations of polymer resin and additive choice in cap manufacturing, more homogeneous waste streams could be derived from plastic bottle cap recycling, enabling recycling into more demanding and valuable applications.

Synthesis and characterization of diaminomaleonitrile-functionalized polystyrene grafts for application in pervaporation separation

2008 ◽  
Vol 62 (4) ◽  
Author(s):  
Hamada Abdel-Razik
Keyword(s):  
Chemical Structure ◽  
Thermal Characteristics ◽  
Gravimetric Analysis ◽  
Thermal Gravimetric ◽  
Optimum Conditions ◽  
Scanning Calorimetry ◽  
Phenol Water ◽  
Pervaporation Separation ◽  
Thermal Stability Of

AbstractSynthesis, characterization and application of diaminomaleonitrile (DAMN)-functionalized polystyrene grafts were studied. Dibenzoyle peroxide (BP) was used as an initiator. Optimum conditions for grafting were found to be c(DAMN) = 0.5 M, c(BP) = 0.016 M, θ = 85 °C and t = 4 h. Water uptake of the polystyrene graft membranes was found to increase with the increase of the grafting yield. The chemical structure, thermal characteristics and thermal stability of the obtained membranes were investigated by means of FTIR spectroscopy, differential scanning calorimetry, and thermal gravimetric analysis. Polystyrene graft membrane with the degree of grafting of up to 96 % was found to be useful for the pervaporation separation of phenol/water mixtures.

Purification and characterization of kraft lignin

Holzforschung ◽  
2015 ◽  
Vol 69 (8) ◽  
pp. 943-950 ◽  
Author(s):  
Wenwen Fang ◽  
Marina Alekhina ◽  
Olga Ershova ◽  
Sami Heikkinen ◽  
Herbert Sixta
Keyword(s):  
Thermal Properties ◽  
High Performance ◽  
Inorganic Compounds ◽  
Gel Permeation Chromatography ◽  
Kraft Lignin ◽  
Hot Water ◽  
Scanning Calorimetry ◽  
Target Values ◽  
Lower Glass Transition Temperature

Abstract To upgrade the utilization of kraft lignin (KL) for high-performance lignin-based materials (e.g., carbon fiber), the purity, molecular mass distribution (MMD), and thermal properties need to be improved and adjusted to target values. Therefore, different methods, such as ultrasonic extraction (UE), solvent extraction, dialysis, and hot water treatment (HWT), were applied for the purification of KL. The chemical and thermal properties of purified lignin have been characterized by nuclear magnetic resonance, Fourier transform infrared, gel permeation chromatography, elemental analysis, differential scanning calorimetry, and thermogravimetric analysis. The lignin fractions obtained by UE with ethanol/acetone (E/A) mixture (9:1) revealed a very narrow MMD and were nearly free of inorganic compounds and carbohydrates. Further, the E/A-extracted lignin showed a lower glass transition temperature (Tg) and a clearly detectable melting temperature (Tm). Dialysis followed by HWT at 220°C is an efficient method for the removal of inorganics and carbohydrates; however, lignin was partly forming condensed structures during the treatment.

scholarly journals Commentary: Considerations in the Measurement of Glass Transition Temperatures of Pharmaceutical Amorphous Solids

2019 ◽  
Vol 21 (1) ◽  
Author(s):  
Ann Newman ◽  
George Zografi
Keyword(s):  
Glass Transition ◽  
Amorphous Solid ◽  
Amorphous Solids ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Preparation Methods ◽  
Glass Transition Temperatures ◽  
Pharmaceutical Applications ◽  
Sample Preparation Methods

AbstractAn increased interest in using amorphous solid forms in pharmaceutical applications to increase solubility, dissolution, and bioavailability has generated a need for better characterization of key properties, such as the glass transition (Tg) temperature. Although many laboratories measure and report this value, the details around these measurements are often vague or misunderstood. In this article, we attempt to highlight and compare various aspects of the two most common methods used to measure pharmaceutical Tg values, conventional and modulated differential scanning calorimetry (DSC). Issues that directly impact the Tg, such as instrumental parameters, sample preparation methods, data analysis, and “wet” vs. “dry” measurements, are discussed.

Interaction of Human-Like Collagen with Copper (II): Effect on Thermal Characteristics

2013 ◽  
Vol 721 ◽  
pp. 625-628
Author(s):  
Yuan Yan Yu
Keyword(s):  
Aqueous Solution ◽  
Differential Scanning Calorimetry ◽  
Copper Complex ◽  
Thermal Characteristics ◽  
Solution Technique ◽  
Dsc Analysis ◽  
Scanning Calorimetry ◽  
Thermo Gravimetric ◽  
Pure Protein

This work describes the aqueous-solution technique preparation and characterization of the complex between human-like collagen and copper (II). Pure human-like collagen and the copper complex were characterized by thermo gravimetric (TG) and differential scanning calorimetry (DSC) analysis. The TG curves and DSC data reveal the significant thermal differences between pure protein and the copper complex, demonstrating the formation of a new chemical compound, which is different from the free HLC and with more stable thermodynamic properties.

Synthesis and Characterization of a POSS-Urethane Hybrid Coating for Use in the Corrosion Protection of Metal

2005 ◽  
Vol 23 ◽  
pp. 231-234 ◽  
Author(s):  
Matthew Oaten ◽  
Namita Roy Choudhury
Keyword(s):  
Corrosion Protection ◽  
Photoelectron Spectroscopy ◽  
Hybrid Coating ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Clean Steel ◽  
X Ray ◽  
Oligomeric Silsesquioxane ◽  
Steel Substrates

The potential of cyclic silsesquioxanes as flexible coatings has been explored in this work for corrosion protection of metal. A polyurethane coating containing an inorganic polyhedral oligomeric silsesquioxane (POSS) was synthesized and characterized by means of photo-acoustic infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle and modulated differential scanning calorimetry (MDSC). The coating has been applied to clean steel substrates via dip and spin coating. The POSS based hybrid coating is found to be uniform, dense and essentially defect free. XPS shows that the coating forms a lamellar layered structure on the substrate.

Thermal Characterization of Bacterial Cellulose/Polyvinyl Alcohol Nanocomposite

2015 ◽  
Vol 1123 ◽  
pp. 303-307 ◽  
Author(s):  
Akhmad Zainal Abidin ◽  
Hafis Pratama Rendra Graha
Keyword(s):  
Bacterial Cellulose ◽  
Melting Temperature ◽  
Healing Process ◽  
Thermal Characteristics ◽  
Cost Effective ◽  
Thermal Characterization ◽  
Fermentation Medium ◽  
Scanning Calorimetry ◽  
Regeneration Rate

Bacterial cellulose (BC) is a natural polymer which can be produced from various substrates easily found in Indonesia. Bacterial cellulose is believed to be a promising and cost effective bone scaffold in which a bone regeneration rate enhanced so the healing process is faster. In this experiment, Bacterial Cellulose (BC)/ Polyvin y l Alcohol (PVA) nanocomposite was made to give a further improvement in the properties. This nanocomposite was made thorough BC biosynthesis in Gluconacetobacter xylinus fermentation medium that was modified by addition of PVA. The PVA concentrations were varied as 0, 3, 6, 9, and 12 % w of fermentation medium. The culture had been agitated by magnetic stirrer for 28 days before freeze drying method was conducted to obtain dry BC/PVA nanocomposite. The product of BC/PVA nanocomposite was then studied for thermal characteristics using Differential Scanning Calorimetry (DSC) and Thermogravimetry Analysis (TGA). Pure BC has melting temperature (Tm) at 350 . 3oC and pure PVA at 181 . 3oC. Experimental results showed that the higher PVA content in fermentation medium decreased the melting temperature of BC/PVA nanocomposite produced.

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