scholarly journals Poly(Urethane-Acrylate) Aerogels via Radical Polymerization of Dendritic Urethane-Acrylate Monomers

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2249 ◽  
Author(s):  
Maria Papastergiou ◽  
Aspasia Kanellou ◽  
Despoina Chriti ◽  
Grigorios Raptopoulos ◽  
Patrina Paraskevopoulou
Keyword(s):  
Thermal Stability ◽  
Material Properties ◽  
Urethane Acrylate ◽  
Porous Network ◽  
Surface Areas ◽  
Similar Materials ◽  
Free Radical Chemistry ◽  
Acrylate Monomers ◽  
First Time

The purpose of this work was to investigate the effect of multifunctionality on material properties of synthetic polymer aerogels. For this purpose, we present the synthesis and characterization of monolithic dendritic-type urethane-acrylate monomers based on an aliphatic/flexible (Desmodur N3300), or an aromatic/rigid (Desmodur RE) triisocyanate core. The terminal acrylate groups (three at the tip of each of the three branches, nine in total) were polymerized with 2,2′-azobis(isobutyronitrile) (AIBN) via free radical chemistry. The resulting wet-gels were dried with supercritical fluid (SCF) CO2. Aerogels were characterized with ATR-FTIR and solid-state 13C NMR. The porous network was probed with N2-sorption and scanning electron microscopy (SEM). The thermal stability of aerogels was studied with thermogravimetric analysis (TGA). Most aerogels were macroporous materials (porosity > 80%), with high thermal stability (up to 300 °C). Aerogels were softer at low monomer concentrations and more rigid at higher concentrations. The material properties were compared with those of analogous aerogels bearing only one acrylate moiety at the tip of each branch and the same cores, and with those of analogous aerogels bearing norbornene instead of acrylate moieties. The nine-terminal acrylate-based monomers of this study caused rapid decrease of the solubility of the growing polymer and made possible aerogels with much smaller particles and much higher surface areas. For the first time, aliphatic/flexible triisocyanate-based materials could be made with similar properties in terms of particle size and surface areas to their aromatic/rigid analogues. Finally, it was found that with monomers with a high number of crosslinkable groups, material properties are determined by multifunctionality and thus aerogels based on 9-acrylate- and 9-norbornene-terminated monomers were similar. Materials with aromatic cores are carbonizable with satisfactory yields (20–30% w/w) to mostly microporous materials (BET surface areas: 640–740 m2 g−1; micropore surface areas: 360–430 m2 g−1).

scholarly journals Gas sorption porosimetry for the evaluation of hard carbons as anodes for Li- and Na-ion batteries

2020 ◽  
Vol 11 ◽  
pp. 1217-1229
Author(s):  
Yuko Matsukawa ◽  
Fabian Linsenmann ◽  
Maximilian Arthur Plass ◽  
George Hasegawa ◽  
Katsuro Hayashi ◽  
...  
Keyword(s):  
Metal Ion ◽  
High Capacity ◽  
Quantitative Relation ◽  
Gas Sorption ◽  
Carbon Particles ◽  
Surface Areas ◽  
Commercial Viability ◽  
Similar Materials ◽  
Scientific Challenge

Hard carbons are promising candidates for high-capacity anode materials in alkali metal-ion batteries, such as lithium- and sodium-ion batteries. High reversible capacities are often coming along with high irreversible capacity losses during the first cycles, limiting commercial viability. The trade-off to maximize the reversible capacities and simultaneously minimizing irreversible losses can be achieved by tuning the exact architecture of the subnanometric pore system inside the carbon particles. Since the characterization of small pores is nontrivial, we herein employ Kr, N2 and CO2 gas sorption porosimetry, as well as H2O vapor sorption porosimetry, to investigate eight hard carbons. Electrochemical lithium as well as sodium storage tests are compared to the obtained apparent surface areas and pore volumes. H2O, and more importantly CO2, sorption porosimetry turned out to be the preferred methods to evaluate the likelihood for excessive irreversible capacities. The methods are also useful to select the relatively most promising active materials within chemically similar materials. A quantitative relation of porosity descriptors to the obtained capacities remains a scientific challenge.

scholarly journals Investigation on pyrolysis of some organic raw materials

2017 ◽  
Vol 17 (43) ◽  
pp. 5-13
Author(s):  
Purevsuren B ◽  
Davaajav Ya ◽  
Batbileg S ◽  
Ariunaa A ◽  
Namkhainorov J ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Epoxy Resin ◽  
Raw Materials ◽  
Gaseous Products ◽  
Animal Bone ◽  
Waste Milk ◽  
Heavy Fractions ◽  
Milk Casein ◽  
First Time

We have been working on pyrolysis of some organic raw materials including different rank coals, oil shale, wood waste, animal bone, cedar shell, polypropylene waste, milk casein and characterization of obtained hard residue, tar and pyrolytic water and gas after pyrolysis. The technical characteristics of these organic raw materials have been determined and the thermal stability characteristics such as thermal stability indices (T5% and T25%) determined by using thermogravimetric analysis. The pyrolysis experiments were performed at different heating temperatures and the yields of hard residue, tar, pyrolysis water and gaseous products were determined and discussed. The main technical characteristics of hard residue of organic raw materials after pyrolysis have been determined and the adsorption ability of pyrolysis hard residue and its activated carbon of organic raw materials also determined. The pyrolysis tars of organic raw materials were distilled in air condition and determined the yields of obtained light, middle and heavy fractions and bitumen like residue with different boiling temperature. This is the first time to investigate the curing ability of pyrolysis tars of organic raw materials for epoxy resin and the results of these experiments showed that only tar of milk casein has the highest (95.0%), tar of animal bone has certain (18.70%) and tars of all other organic raw materials have no curing ability for epoxy resin.

Characterization of Some Lincomycin and Cyclamate Salts by Thermal Analysis and Infrared Spectroscopy

1971 ◽  
Vol 54 (5) ◽  
pp. 1200-1210 ◽  
Author(s):  
G A Neville ◽  
J C Ethier ◽  
N F H Bright ◽  
R H Lake
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Sulfamic Acid ◽  
Thermal Dehydration ◽  
Sodium Cyclamate ◽  
First Time ◽  
Derivatives Of ◽  
Relative Thermal Stability ◽  
Thermal Stability Of

Abstract The relative thermal stability of lincomycin. HCl.H2O, lincomycin cyclamate, calcium cyclamate.2H2O, and sodium cyclamate was studied by differential thermal analysis and by thermogravimetric analysis. Lincomycin. HCl.H2O easily undergoes thermal degradation with the release of methyl mercaptan, but the cyclamate anion confers considerably greater thermal stability on the lincomycin moiety. Calcium cyclamate.2H2O was found to undergo a 2-step thermal dehydration analogous to that undergone by CaSO4.2H2O, including termination in the formation of CaSO4· Grating infrared spectra are reproduced for lincomycin.HCl.H2O, cyclohexylsulfamic acid (cyclamic acid), sodium cyclamate, and calcium cyclamate.2H20. Principal group frequencies are assigned with the aid of deuterium exchange studies and thermal dehydration limits. Infrared characteristics of derivatives of sulfamic acid are described for the first time and evidence is presented for the trans amide configuration in lincomycin. HCl.H2O.

scholarly journals Extraction and Characterization of New Cellulose Fiber from the Agrowaste of Lagenaria Siceraria (Bottle Guard) Plant

2016 ◽  
Vol 12 (9) ◽  
pp. 4382-4388 ◽  
Author(s):  
N. Saravanan ◽  
P.S. Sampath ◽  
T.A. Sukantha
Keyword(s):  
Thermal Stability ◽  
Tensile Strength ◽  
Natural Fiber ◽  
Cellulose Fiber ◽  
Crystalline Size ◽  
Low Density ◽  
Lagenaria Siceraria ◽  
Plant Stem ◽  
First Time

This article explores the extraction and characterization of natural fiber from the agro-waste of Lagenaria siceraria (LS)plant stem (commonly known as „bottle guard‟) for the first time. The extracted fiber from the waste stems has highcellulose content (79.91 %) with good tensile strength (257–717 MPa) and thermal stability (withstand up to 339.1°C). Theimmense percentage of crystalline index (92.4%) with the crystalline size (7.2 nm) as well as low density (1.216 g/cm3) ofthe LS fiber renders their possibilit

scholarly journals Preparation and Characterization of Calcium Cross-Linked Starch Monolithic Cryogels and Their Application as Cost-Effective Green Filters

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3975
Author(s):  
Chanita Boonkanon ◽  
Kharittha Phatthanawiwat ◽  
Laemthong Chuenchom ◽  
Nareumon Lamthornkit ◽  
Tarawee Taweekarn ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Cost Effective ◽  
Dry Weight ◽  
Rice Flour ◽  
Monolithic Material ◽  
Surface Areas ◽  
First Time ◽  
Interconnected Pores ◽  
Resultant Material

Monolithic cryogels from starch were successfully synthesized and applied as alternative biodegradable filters for the first time. Rice flour was cross-linked with Ca2+ from limewater during gelatinization before being frozen and then thawed for three cycles. The resultant material was then soaked in ethanol for 3 h before incubation at 80 °C for 1 h, yielding monolithic material with interconnected pores in sizes of 51 ± 18 to 52 ± 15 µm without any need of freeze-drying. The cryogels possessed macroporous structure with specific surface areas from 1.1 to 4.3 m2g−1, they could adsorb water from 599 ± 27 to 635 ± 59% of their dry weight with low swelling ratios of 6.0 ± 0.3 to 6.4 ± 0.6 gwater/gcryogel, and could be applied as biofilters to remove suspended particles and reduce the light absorption of water sample from 25 ± 3 to 96 ± 5%. The prepared biofilters can be re-used up to three times, although they cost only USD 0.0004/piece. Complete weight loss resulted from burial in soil for 30 days, indicating environmentally friendly biodegradation and potential for environmental applications.

TBE in Sweden

2020 ◽  
Keyword(s):  
Genetic Characterization ◽  
Immunoglobulin M ◽  
Enzyme Linked Immunosorbent Assay ◽  
Second Phase ◽  
Serum Samples ◽  
Tick Borne Encephalitis ◽  
Specific Immunoglobulin ◽  
Tick Borne Encephalitis Virus ◽  
First Time

Tick-borne encephalitis virus (TBEV) was isolated for the first time in Sweden in 1958 (from ticks and from 1 tick-borne encephalitis [TBE] patient).1 In 2003, Haglund and colleagues reported the isolation and antigenic and genetic characterization of 14 TBEV strains from Swedish patients (samples collected 1991–1994).2 The first serum sample, from which TBEV was isolated, was obtained 2–10 days after onset of disease and found to be negative for anti-TBEV immunoglobulin M (IgM) by enzyme-linked immunosorbent assay (ELISA), whereas TBEV-specific IgM (and TBEV-specific immunoglobulin G/cerebrospinal fluid [IgG/CSF] activity) was demonstrated in later serum samples taken during the second phase of the disease.

Chemical Constituents and Antibacterial Activity of Cissus Aralioides.

2020 ◽  
Vol 17 ◽  
Author(s):  
Balogun Olaoye Solomon ◽  
Ajayi Olukayode Solomon ◽  
Owolabi Temitayo Abidemi ◽  
Oladimeji Abdulkarbir Oladele ◽  
Liu Zhiqiang
Keyword(s):  
Plant Extract ◽  
Chemical Constituents ◽  
Ethyl Acetate Fraction ◽  
Antibacterial Activities ◽  
Sub Saharan Africa ◽  
Chromatographic Purification ◽  
Whole Plant ◽  
Sub Saharan ◽  
First Time

: Cissus aralioides is a medicinal plant used in sub-Saharan Africa for treatment of infectious diseases; however the chemical constituents of the plant have not been investigated. Thus, in this study, attempt was made at identifying predominant phytochemical constituents of the plant through chromatographic purification and silylation of the plant extract, and subsequent characterization using spectroscopic and GC-MS techniques. The minimum inhibitory concentration (MICs) for the antibacterial activities of the plant extract, chromatographic fractions and isolated compounds were also examined. Chromatographic purification of the ethyl acetate fraction from the whole plant afforded three compounds: β-sitosterol (1), stigmasterol (2) and friedelin (3). The phytosterols (1 and 2) were obtained together as a mixture. The GC-MS analysis of silylated extract indicated alcohols, fatty acids and sugars as predominant classes, with composition of 24.62, 36.90 and 26.52% respectively. Results of MICs indicated that friedelin and other chromatographic fractions had values (0.0626-1.0 mg/mL) comparable with the standard antibiotics used. Characterization of natural products from C. aralioides is being reported for the first time in this study.

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