• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3249-3253
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• 2014

A novel triazole-functionalized phenolic resin was developed, and its thermal and flame-retardant properties were investigated. The triazole group was incorporated as a pendant unit on the phenolic resin via copper-mediated click chemistry between propargylated phenolic resin and benzyl azide. The newly-developed triazole-functionalized phenolic resin showed higher thermal stability and char yield, together with a reduced total heat release (THR), than the non-functionalized bare phenolic resin, indicating enhanced flame retardancy for the triazole-functionalized phenolic resin.

• Journal of Soil and Groundwater Environment
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• v.19 no.5
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• pp.45-52
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• 2014

Torrefaction and hydrothermal carbonization (HTC) are productive methods to reclaim energy from lignocellulosic biomass. The hydrophobic, homogenized, energy dense and carbon rich solid fuel can be obtain from torrefaction and hydrothermal carbonization. Dead leaves were carbonized in a stainless steel reactor of volume 200 ml with torrefaction ($250-270^{\circ}C$) for 120 minutes and hydrothermal carbonization ($200-250^{\circ}C$) for 30 minutes, with mass yield solid fuel ranging from 57-70% and energy content from 16.81MJ/kg to 22.01 MJ/kg compare to the biomass. The char produced from torrefaction process possess high energy content than hydrothermal carbonization. The highest energy yield of 89.96% was obtained by torrefaction at $250^{\circ}C$. The energy densification ratio fluctuated in between 1.15 to 1.30. On the basis of pore size distribution of the chars, the definition of the International Union of Pure and Applied Chemistry (IUPAC) was used as a classification standard. The pore diameter was ranging within 11.09-19 nm which play important role in water holding capacity in soil. Larger pores can hold water and provide passage for small pores. Therefore, it can be concluded that high pore size char can be obtained my HTC process and high energy content char of 22.01 MJ/Kg with 34.04% increase in energy can be obtain by torrefaction process.

• Carbon letters
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• v.26
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• pp.66-73
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• 2018

We assessed the effects of combining bio-char with straw residue mulching on the loss of soil soluble nutrients and citrus yield in sloping land. The two-year study showed that straw residue mulching (ST) and bio-char application combined with straw residue (ST+BC) can significantly reduce soil soluble nutrient loss when compared with the control treatment (CK). The comparative volume of the soil surface runoff after each of the treatments was as follows: CK > ST > ST + BC. Compared with the CK, the runoff volume of the ST was reduced by 13.6 % and 8.5 % in 2014 and 2015, respectively. Compared with the CK, combining bio-char with the ST application reduced the loss of soluble nitrogen and improved the soil total nitrogen content reaching a significant level in 2015. It dramatically increased the soil organic matter content over the two year period (36.3% in 2014, 50.6% in 2015) as well as the carbon/nitrogen ratio (C/N) (16.6% in 2014 and 39.3% in 2015). Straw mulching combined with bio-char showed a trend for increasing the citrus yield.

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.371-378
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• 2019

Graphene nanoplatelet (GnP)/reused phenolic foam (re-PF)/wood composite boards were fabricated with different GnP content as 5, 10 and 20 w/w% to investigate the effect of GnP on thermal- and flame retardant properties of wood-based composite boards. The thermal- and flame retardant properties of fabricated composite boards were investigated by thermogravimetric analysis (TGA) and limiting oxygen index (LOI), respectively. The thermal stability of the composite boards increased proportionally with respect to the amount of GnP, and the char yield of these boards increased up to 22% compared to that of the pure wood board. The LOI values of composite boards were about 4.8~7.8% higher than those of using pure wood boards. It was also confirmed that the flame retardant properties of composite boards were remarkably improved by the addition of re-PF and GnP. These results were because of the fact that the re-PF and GnP with a high thermal stability delayed the initial thermal degradation temperature of composite boards and made their char layers denser and thicker which led the overall combustion delay effect of the composite board. Especially, GnP as a carbon-based material, facilitated the char layer formation and increased remarkedly the char yield, which showed higher effect on flame retardant properties than those of the re-PF.

• Fire Science and Engineering
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• v.12 no.4
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• pp.41-49
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• 1998

In this study, the thermal improvement of an isophthalic acid polyester resin by the incorporation of flame retardants has been investigated. Aluminium hydroxide, antimony oxide and alumina powder were used to formulate the flame retardant systems. The improvement of an isophthalic resin by incorporating aluminium hydroxide is dramatic(burning rate and smoke emission are reduced), although the mechanical property is decreased significantly. The addition of small amount(2.5 phr) of antimony oxide produces high char yield(31%) which acts as a protective layer on the surface of the resin.

• Elastomers and Composites
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• v.54 no.4
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• pp.321-329
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• 2019

A series of poly(hyroxyamide)s (PHAs) was prepared by direct polycondensation reaction of 4,4'-(2,3-pyridinedioxy)dibenzoic acid and/or isophthalic acid with 3,3'-dihydroxybenzidine. The yield percentages of the products were high, and the inherent viscosities of the polymer in DMAc solution at 35℃ were 0.31-0.59 dL/g. All PHA polymers were found to be soluble in polar aprotic solvents such as DMAc, DMSO, NMP, and DMF. On the other hand, LiCl was required to dissolve IPHA-1 in aprotic solvents. Poly(benzoxazole)s (PBOs) were partially soluble in conc-H₂SO₄; IPBO-4, -5, and -6 were partially soluble in NMP only when LiCl was added to the solution, and the solution was heated. The PBO polymers showed a maximum weight loss in the temperature range of 654-680℃, and the char yields at 900℃ under nitrogen atmosphere exceeded 63%.

• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.31-42
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• 2007

To investigate the pyrolytic and anatomical characteristics of Korean softwood, Pinus densi-flora, Pinus rigida and Larix leptolepis, and hardwood, Acer palntatum, Fraxinus rhynchophylla and Quercus variabilis, chemical components analysis, TG-DTA (Thermogravimetric Analysis & Differential Thermal Analysis), MBA (Methylene Blue Adsorption) test and SEM observation were carried out. For TG-DTA, samples were carbonized up to $800^{\circ}C$ at the heating rate of $10^{\circ}C$/min under $N_2$ flows 1 l/min using thermogravimetric analyzer. Chemical component analysis of all samples resulted in typical contents of major wood component. In TG-DTA results, softwood showed higher char yield than hardwood, and lignin displayed the highest char yield among the major wood components. All samples showed typical TGA, DTG and DTA curves for wood pyrolysis except a few differences between softwood and hardwood. Content of lignin influenced its pyrolysis characteristics, while molecular structure of lignin affected not only the weight loss but also the yield of char. In MBA test results, MBA of softwoods was higher than that of hardwoods. Char of Pinus densiflora showed the highest MBA, but its degree was lower than activated carbon or fine charcoal about 23 and 4 times, respectively. SEM observation showed carbonization process preserves wood structure and retain the micro-structure of wood fibers.

• Elastomers and Composites
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• v.39 no.2
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• pp.105-120
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• 2004

The flame retarded NBR foams were prepared with metal hydroxides and various phosphorus/nitrogen-contain ing flame retardants. The dependency of the phosphorus content on thermal properties, flame retardancy, smoke density, and foaming properties were investigated in the foams. Foaming properties and morphology of the flame retarded NBR foams with P/N flame retardants( ${\le}10 phr$) were similar to those of the foams without P/N ones but containing metal hydroxides The flame retardancy of the foams was improved with increasing the phosphorus content and char formation under combustion atmosphere. The cone-calorimeter test and LOI index were also coincided with the TGA analysis quite well. The heat release rate (HRR), total heat release (THR), and effective heat of combustion (EHC) were decreased, whereas the carbon monoxide yield was increased with increase of the phosphorus content of P/N flame retardant. The smoke density values were closely related with CO yield values obtained by the cone-calorimeter test due to the high and hard char formation.

• Carbon letters
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• v.28
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• pp.66-71
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• 2018

To improve the flame retardant performance of cellulose fibers, fluorine functional groups were introduced under various controlled fluorination conditions. The properties of the fluorinated cellulose fibers were analyzed by X-ray photoelectron spectroscopy and a thermogravimetric analysis. The fluorine functional group content in the fluorinated cellulose fibers increased with an increase in the fluorination temperature. However, the fluorination reaction increased the char yield and decreased the rate of degradation of the cellulose fibers by introducing donors, enabling the formation of a thick and compact char layer. Therefore, the flame retardant properties of cellulose fibers were improved following the fluorination treatment.

• Elastomers and Composites
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• v.55 no.3
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• pp.205-214
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• 2020

A series of wholly aromatic polyhyroxyamide (PHA) copolymers were prepared by direct polycondensation reaction of isophthalic acid and diacids containing bulky units with 3,3'-dihydroxybenzidine. The inherent viscosities of the PHAs measured at 35℃ in DMAc solution were in the range of 0.31-0.56 dL/g. The solubility study revealed that the PHAs were readily soluble in aprotic solvents such as, dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP) at room temperature and in less polar solvent such as pyridine. However, the polybenzoxazole (PBO) copoymers were quite insoluble in all organic solvents except partially soluble in concentrated sulfuric acid and partially soluble in NMP containing LiCl. The PBO copolymers showed maximum weight loss temperature in the range of 593-632℃ and high char yields in the range of 65.0-71.2% at 900℃ in a nitrogen atmosphere.