Thermal degradation of oriental beech wood impregnated with different inorganic salts

This study investigated the thermal properties of Oriental beech (Fagus orientalis) treated with (NH4)2HPO4, K2HPO4, NH4Cl and (NH4)2SO4 salts and their mixtures (1:1; w/w) aqueous solutions at 3% concentrations. The effects of different inorganic salts fire retardants on the thermal degradation characteristics of wood samples were evaluated by thermogravimetric analysis (TGA). Based on the TGA curve for untreated beech wood, weight loss takes place at three distinct steps. The impregnation of inorganic salts resulted in higher char yields and additional thermal degradation steps were identified. The highest char yield (80%) was obtained from (NH4)2HPO4-K2HPO4 mixture impregnated sample.  Salt mixtures containing phosphates ((NH4)2HPO4 and K2HPO4) have remarkable effects on thermal stability of beech wood, whereas NH4Cl salt lowered the decomposition temperatures and char yield. &nbsp

Synthesis and surface properties of polydimethylsiloxane-based block copolymers: poly[dimethylsiloxane-block- (ethyl methacrylate)] and poly[dimethylsiloxane-block-(hydroxyethyl methacrylate)]

A polydimethylsiloxane (PDMS) macroazoinitiator was synthesized from bis(hydroxyalkyl)-terminated PDMS and 4,4'-azobis-4- cyanopentanoic acid by a condensation reaction. The bifunctional macroinitiator was used for the block copolymerization of ethyl methacrylate (EMA) and 2-(trimethylsilyloxy) ethyl methacrylate (TMSHEMA) monomers. The poly(DMS-block-EMA) and poly(DMS-block-TMSHEMA) copolymers thus obtained were characterized using Fourier transform infrared and (1)H NMR spectroscopy and differential scanning calorimetry. After the deprotection of trimethylsilyl groups, poly(DMS-block-HEMA) and poly(DMS-block-EMA) copolymer film surfaces were analysed using scanning electron microscopy and X-ray photoelectron spectroscopy. The effects of the PDMS concentration in the copolymers on both air and glass sides of films were examined. The PDMS segments oriented and moved to the glass side in poly(DMS-block-EMA) copolymer film while orientation to the air side became evident with increasing DMS content in poly(DMS-block-HEMA) copolymer film. The block copolymerization technique described here is a versatile and economic method and is also applicable to a wide range of monomers. The copolymers obtained have phase-separated morphologies and the effects of DMS segments on copolymer film surfaces are different at the glass and air sides. (C) 2010 Society of Chemical Industr

Thermal degradation of oriental beech wood impregnated with different inorganic salts

This study investigated the thermal properties of Oriental beech (Fagus orientalis) treated with (NH4)2HPO4, K2HPO4, NH4Cl and (NH4)2SO4 salts and their mixtures (1:1; w/w) aqueous solutions at 3% concentrations. The effects of different inorganic salts fire retardants on the thermal degradation characteristics of wood samples were evaluated by thermogravimetric analysis (TGA). Based on the TGA curve for untreated beech wood, weight loss takes place at three distinct steps. The impregnation of inorganic salts resulted in higher char yields and additional thermal degradation steps were identified. The highest char yield (80%) was obtained from (NH4)2HPO4-K2HPO4 mixture impregnated sample.  Salt mixtures containing phosphates ((NH4)2HPO4 and K2HPO4) have remarkable effects on thermal stability of beech wood, whereas NH4Cl salt lowered the decomposition temperatures and char yield.

Atomic Fe on hierarchically ordered porous carbon towards high-performance Lithium-sulfur batteries

Lithium-sulfur (Li-S) battery is the promising next-generation energy storage device owing to its ultra-high theoretical energy density and low cost. Unfortunately, its practical performance is significantly hindered by the poor conductivity of sulfur, huge volume change, and soluble lithium polysulfides (LiPSs). To address above issues, single iron (Fe) atoms anchored on hierarchically porous carbon substrate configured by ordered macropores and widespread mesopores/micropores (Fe[sbnd]N[sbnd]C/OC) are synthesized and acted as carbon hosts for sulfur cathodes. Single Fe atoms in Fe-N4 moieties serve as active sites to accelerate conversion kinetics of LiPSs due to strong catalytic ability, thereby the shuttle effect being obviously restrained. Meanwhile, the trimodal-porous structure provides continuous carbon framework for enhanced electrical conductivity, ordered macroporous channels bridged by mesopores for rapid Li+ diffusion, and adequate spaces to reserve sulfur volume oscillation. Consequently, sulfur-loaded Fe[sbnd]N[sbnd]C/OC (Fe[sbnd]N[sbnd]C/OC/S) cathodes exhibit an impressive specific capacity of 1442 mAh g−1 at 0.1C and maintain the capacity retention of 89.2 % after 300 cycles at 1C. It offers fresh insights for designing efficient sulfur hosts to enhance the performance of Li-S batteries. © 2022 Elsevier B.V.LTT20005; 21PJD018; National Natural Science Foundation of China, NSFC: 22108079; China Postdoctoral Science Foundation: 2020M681208National Natural Science Foundation of China [22108079]; Shanghai Pujiang Program [21PJD018]; China Postdoctoral Science Foundation [2020M681208]; Czech Ministry of Education, Youth and Sports INTER -EXCELLENCE [LTT20005]; Feringa Nobel Prize Scientist Joint Research Cente

Synthesis and Characterization of 2-Hydroxyethyl Methacrylate (HEMA) and Methyl Methacrylate (MMA) Copolymer Used as Biomaterial

A series of poly(methyl methacrylate-co-hydroxyethyl methacrylate) (PMMA-co-PHEMA), copolymers were synthesized by an emulsion polymerization technique. Copolymer compositions were determined by FT-IR and 1H-NMR spectroscopy. It was found that comonomer ratios used in the recipes were comparable within the actual copolymers. Glass transition temperatures (Tg) of PMMA-co-PHEMA copolymers were varied from 119 degrees C to 100 degrees C by increasing HEMA content. Thermogravimetric analysis showed that the copolymers were stable up to 330 degrees C. High intrinsic viscosity values of copolymer resulted in ductile solution-cast films. The hydrophilicity of the films was analyzed by water uptake measurements

Tailoring the Swelling and Glass-Transition Temperature of Acrylonitrile/Hydroxyethyl Acrylate Copolymers

Novel polyacrylonitrile (PAN)-co-poly(hydroxyethyl acrylate) (PHEA) copolymers at three different compositions (8,12, and 16 mol % PHEA) and their homopolymers were synthesized systematically by emulsion polymerization. Their chemical structures and compositions were elucidated by Fourier transform infrared, H-1-NMR, and C-13-NMR spectroscopy. Intrinsic viscosity measurements revealed that the molecular weights of the copolymers were quite enough to form ductile films. The influence of the molar fraction of hydroxyethl acrylate on the glass-transition temperature (T-g) and mechanical properties was demonstrated by differential scanning calorimetry and tensile test results, respectively. Additionally, thermogravimetric analysis of copolymers was performed to investigate the degradation mechanism. The swelling behaviors and densities of the free-standing copolymer films were also evaluated. This study showed that one can tailor the hydrogel properties, mechanical properties, and T-g's of copolymers by changing the monomer feed ratios. On the basis of our findings, PAN-co-PHEA copolymer films could be useful for various biomaterial applications requiring good mechanical properties, such as ophthalmic and tissue engineering and also drug and hormone delivery. (C) 2009 Wiley Periodicals, Inc. J AppI Polyrn Sci 116: 628-635, 201

Carboxymethylated and Sulfated Furcellaran from <i>Furcellaria lumbricalis</i> and Its Immobilization on PLA Scaffolds

This study involved the creation of highly porous PLA scaffolds through the porogen/leaching method, utilizing polyethylene glycol as a porogen with a 75% mass ratio. The outcome achieved a highly interconnected porous structure with a thickness of 25 μm. To activate the scaffold’s surface and improve its hydrophilicity, radiofrequency (RF) air plasma treatment was employed. Subsequently, furcellaran subjected to sulfation or carboxymethylation was deposited onto the RF plasma treated surfaces with the intention of improving bioactivity. Surface roughness and water wettability experienced enhancement following the surface modification. The incorporation of sulfate/carboxymethyl group (DS = 0.8; 0.3, respectively) is confirmed by elemental analysis and FT-IR. Successful functionalization of PLA scaffolds was validated by SEM and XPS analysis, showing changes in topography and increases in characteristic elements (N, S, Na) for sulfated (SF) and carboxymethylated (CMF). Cytocompatibility was evaluated by using mouse embryonic fibroblast cells (NIH/3T3)