흑연 블록의 피치 함침 시 가압 열처리가 함침률에 미치는 영향

권웅,김창규,안태민,정의경 한국섬유공학회 2021 한국섬유공학회지 Vol.58 No.6

Artificial graphite blocks have excellent electrical, thermal, and chemical propertiesand are used in various applications. The impregnation process is an important step inthe artificial graphite block manufacturing process for achieving high density and optimizingvarious performances. However, during the re-carbonization process after the impregnationprocess, the impregnated pitch is melted via temperature increase for recarbonization,and its low molecular weight components are volatilized. This induces elutionof the impregnated pitch that filled the pores of the graphite block, resulting in adecrease in the impregnation rate and an increase in density. Re-impregnation and re-carbonizationprocesses, which are expensive and time-consuming, are required to be performedseveral times to achieve the desired density. Therefore, this study aims to addressthis issue by applying the pressurized heat treatment during the impregnation process. The rates of density increase and impregnation rates are not significantly increased whencompared to those of the impregnated graphite block without pressurized-heat treatment. However, it was found that about 10-20 bar of the pressure could be generated during thethe pressurized-heat treatment, resulting in the increased impregnation rate of the lowerpressure impregnation, which was similar to the higher pressure impregnation.

Preparation of petroleum impregnating pitches from pyrolysis fuel oil using two‑step heat treatments

Jong‑Eun Choi,Seunghyun Ko,Young‑Pyo Jeon 한국탄소학회 2019 Carbon Letters Vol.29 No.4

Petroleum-based impregnating pitches were prepared from pyrolysis fuel oil (PFO) using a two-step heat treatment without a separation process. The pressurized heat treatment, the first step, was used to improve the properties of the pitches and enhance the product yield by promoting the cracking and polymerization of the components in the PFO. An atmospheric heat treatment as the second step was used only to synthesize the impregnating pitches from the liquid pitches prepared during the first step. The prepared impregnating pitches had the properties of a commercial petroleum-based impregnating pitch. The impregnation performance was evaluated by HT-XRD and an impregnation test. The HT-XRD results showed changes in the stacked structure of the pitches at the impregnation temperature. The bulk density of the carbon block was increased to 14.3% and the porosity was reduced by 10.3% after the impregnation/recarbonization process. The high reaction temperature during the first step induced the formation of quinoline insoluble (QI) components during the second step of the treatment, and the QI components adversely affected the impregnation process.

Enhanced antimicrobial effect of organic acid washing against foodborne pathogens on broccoli by vacuum impregnation

Kang, J.W.,Kang, D.H. Elsevier Science Publishers 2016 International journal of food microbiology Vol.217 No.-

<P>This study was undertaken to evaluate the effect of vacuum impregnation applied to the washing process for removal of Salmonella Typhimurium and Listeria monocytogenes from broccoli surfaces. Broccoli was inoculated with the two foodborne pathogens and treated with simple dipping washing or with vacuum impregnation in 2% malic acid for 5, 10, 20, or 30 min. There were two methods of vacuum impregnation: continuous and intermittent. After 30 min of 1013 kPa (=14.7 psi, simple dipping), 613 kPa (=8.9 psi), and 21.3 kPa (=3.1 psi) of continuous vacuum impregnation treatment, there were 1.6, 2.0, and 2.4 log(10) CFU/g reductions of S. Typhimurium and 1.5, 1.7, and 2.3 log(10) CFU/g reductions of L. monocytogenes, respectively. After 30 min of 101.3, 61.3, and 21.3 kPa of intermittent vacuum impregnation treatment, there were 1.5, 2.3, and 3.7 log(10) CFU/g reductions of S. Typhimurium and 1.6, 2.1, and 3.2 log(10) CFU/g reductions of L. monocytogenes, respectively. Scanning electron photomicrographs showed that bacteria tend to attach to or become entrapped in protective sites after simple wash processing (dipping). However, most bacteria were washed out of protective sites after intermittent treatment. Direct treatment of cell suspensions with vacuum impregnation showed that it had no inactivation capacity in itself since there were no significant differences (P >= 0.05) between the reduction rates of non- and vacuum impregnation treatment. These results demonstrate that the increased antimicrobial effect of vacuum impregnation can be attributed to increased accessibility of sanitizer and an enhanced washing effect in protected sites on produce. Color, texture and titratable acidity values of broccoli treated with intermittent vacuum impregnation in 2% malic acid for 30 min were not significantly (P 0.05) different from those of untreated samples even though a storage interval was needed for titratable acidity values to be reduced to levels comparable to those of untreated controls. (C) 2015 Published by Elsevier B.V.</P>

Preparation of petroleum impregnating pitches from pyrolysis fuel oil using two-step heat treatments

최종은,고승현,전영표 한국탄소학회 2019 Carbon Letters Vol.29 No.4

Petroleum-based impregnating pitches were prepared from pyrolysis fuel oil (PFO) using a two-step heat treatment without a separation process. The pressurized heat treatment, the first step, was used to improve the properties of the pitches and enhance the product yield by promoting the cracking and polymerization of the components in the PFO. An atmospheric heat treatment as the second step was used only to synthesize the impregnating pitches from the liquid pitches prepared during the first step. The prepared impregnating pitches had the properties of a commercial petroleum-based impregnating pitch. The impregnation performance was evaluated by HT-XRD and an impregnation test. The HT-XRD results showed changes in the stacked structure of the pitches at the impregnation temperature. The bulk density of the carbon block was increased to 14.3% and the porosity was reduced by 10.3% after the impregnation/recarbonization process. The high reaction temperature during the first step induced the formation of quinoline insoluble (QI) components during the second step of the treatment, and the QI components adversely affected the impregnation process.

Effect of Water-impregnation on Steam Explosion of Pinus densiflora

( Ji Young Jung ),( Si Young Ha ),( Jae-Kyung Yang ) 한국목재공학회 2019 목재공학 Vol.47 No.2

This study addresses the biorefinery feedstock from Pinus densiflora. This raw material is a major tree species in the Republic of Korea; it is renewable, has cost-effective, and is readily available. In this study, steam explosion of P. densiflora was performed in a reactor at 225 ℃ and with 1 to 13 min reaction times with or without previous water impregnation. The combined severity factor (Ro), which is an expression relating the reaction temperature and reaction time used in the steam explosion treatment, ranged from 3.68 to 4.79. The influence of both impregnation and steam explosion conditions were investigated by examining color variations, chemical composition, and mass balance on the pretreated solids. The results showed that steam-exploded P. densiflora that was not impregnated with water exhibited significantly darker color (chroma 28.8-41.4) than water-impregnated and steam-exploded P. densiflora (chroma 18.8-37.3). The increased α-cellulose and lignin contents were detected as the severity factor increased. Furthermore, the α-cellulose and lignin contents in the non-impregnated/steam-exploded P. densiflora were higher than those in the water-impregnated/steam-exploded P. densiflora. However, the decreased holocellulose content was detected as the severity factor increased. In mass balance, the holocellulose yield from water-impregnated/steam-exploded P. densiflora was higher than that from the non-impregnated P. densiflora.

Development of vacuum impregnation equipment and preparation of mass/uniform shape-stabilized phase change materials

Chang, Seong Jin,Wi, Seunghwan,Lee, Jongki,Kim, Sumin Elsevier 2019 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.132 No.-

<P><B>Abstract</B></P> <P>Various industries require production equipment for uniform mass-production short periods of time, such as in the construction industry. This study presents vacuum impregnation equipment that is capable of mass-producing uniform, shape-stabilized PCM (MUSPCM). The vacuum impregnation equipment can manufacture MUSPCM of various diameters without additional filtering and crushing process because the mixing ratio of the SSPCM was analyzed beforehand through a TGA analysis. As the result, MUSPCM using vacuum impregnation equipment can save 32.5 times based on production of 15.0 kg compared to conventional vacuum impregnation. In addition, the analysis of the thermo-physical properties and long-term stability of the MUSPCM were characterized via DSC and TGA analysis. The results indicate that a large amount of uniform MUSPCM were produced, and the long-term phase stability was excellent. Therefore, the developed vacuum impregnation equipment is expected to be useful in various industries, including construction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Vacuum impregnation equipment was developed for mass production of uniform SSPCM. </LI> <LI> MUSPCM was manufactured with various diameters without filtering and crushing process. </LI> <LI> When producing 15.0 kg of MUSPCM, 1570 h shorter than the conventional method. </LI> <LI> The latent heat change rate of MUSPCM was −0.93% over 10,000 cycling tests. </LI> </UL> </P>

Synthesis of copper-poly tetrafluoro-ethylene composites by supercritical impregnation process

Eun-Bong Kim,주창식,Jung-Teag Kim,Si-Young Kim 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.2

This study attempted to develop a copper-PTFE composite consisting of copper nano-particles homogeneously distributed into PTFE using scCO_2. The overall synthesis process consisted of impregnation of copper precursor and thermolytic reduction. The impregnation process was performed over a range of temperature from 40 to 160 ℃ and pressure from 120 to 200 bar. The reduction process was performed at 230℃ and 250 bar for 2 hours consecutively after impregnation. The changes in appearance, mass, and morphology of the PTFE composite were examined by precision balance, SEM, TEM, and EDS. The impregnation ratio increased with temperature up to 120 ℃, but decreased above 120℃. The impregnation ratio increased with the pressure. These results could be explained by dehydration reaction of Cu(hfa)_2H_2O and thermodynamical affinity difference of copper precursors for PTFE or scCO_2. Copper nano-particles impregnated into the PTFE were identified from SEM, TEM and EDS analysis.

사출/압축 공정과 인서트 오버몰딩을 이용한 탄소복합소재 성형에 대한 연구

정의철,윤경환,홍석관,이상용,이성희,Jeong, Eui-Chul,Yoon, Kyung-hwan,Hong, Seok-Kwan,Lee, Sang-Yong,Lee, Sung-Hee 한국금형공학회 2020 한국금형공학회지 Vol.14 No.4

In this study, forming of carbon composite parts was performed using an injection/compression molding process. An impregnation of matrix is determined by ability of wet and flow rate between the matrix and reinforcement. The flow rate of matrix passing through the reinforcements is a function of permeability of reinforcement, a viscosity of matrix and pressure gradient on molding, and the viscosity of the matrix depends on the mold temperature, molding pressure and shear strain of matrix. Therefore, compression molding experiment was conducted using a heating mold in order to confirm the possibility of matrix impregnation. The impregnation of the matrix through the porosities between the woven yarns was confirmed by the cross-sectional SEM image of compression molded parts. An injection molding process was also performed at a short cycle time, high molding pressure and low mold temperature than those of compression experiment conditions. Deterioration of impregnation on the surface of molded parts were caused by these injection conditions and it could be the reason of decreasing the maximum tensile strength. In order to improve impregnation of matrix on the surface, injection/compression molding and insert-over molding were applied. As a result of applying injection/compression molding and insert-over molding, it was shown that the improvement of impregnation on the surface and the maximum tensile strength was increased about 2.8 times than the virgin matrix.

Effect of chemical impregnation on activated carbon fabrics for carbon dioxide capture

( Aafaq Ur Rehman ),( Jin Woong Baek ),( Muhammad Sohail ),( Pham Viet Nguyen ),( Manyandi Venkatesan ),( Shrestha Keshab ),( Hung Suck Park ) 한국폐기물자원순환학회(구 한국폐기물학회) 2016 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2016 No.-

Climate change and acid rain triggered new research opportunities to reduce carbon emissions and acidic gases. However, indoor reduction of CO₂ and acid gases are also the challenging safety issues in building fire. To develop a safety mask with enhanced carbon dioxide adsorption capacity, activated carbon fabrics (ACF) was prepared by copper (II) nitrate trihydrate and ammonium chloride impregnation followed by carbonization and CO₂ adsorption tests were conducted in lab scale reactor with 150 mm in length and internal diameter of 16.12 mm at different moisture conditions (0-40%). Surface area, pore size distribution and cumulative pore volume of ACF samples were examined with BET surface area and porosity analyzer. ACF impregnated with copper showed large surface area (1087 m²·g^-1) and high micre pore volume (0.40 cm³·g^-1) with average pore size of 1.66 nm, while ACF modified with ammonium showed surface area of 861 m²·g^-1 and micro pore volume (0.38 cm³·g^-1) with average pore size of 2.07 nm. This results show that carbonization of fabrics at 450℃ contribute to enhancing surface area as well as micro pore volume. The carbon uptake of ACF modified with ammonium chloride and copper nitrate trihydrate were 49.3 and 85 mg CO₂/g ACF, 29 and 90 mg CO₂/g ACF in dry and 25% moisture contents, respectively. As moisture content increase to 25%, CO₂ adsorption capacity increase to 2-3 times higher than those at dry conditions in both chemicals impregnation. However, further increase in the moisture content to 40% decease adsorption capacity of ACF due to change in functionalities of impregnated chemicals.

Ginsenoside Changes in Red Ginseng Manufactured by Acid Impregnation Treatment

Mi Hyun Kim,Hee-Do Hong,Young-Chan Kim,Young Kyoung Rhee,Kyung Tack Kim,Jeonghae Rho 고려인삼학회 2010 Journal of Ginseng Research Vol.34 No.2

To enhance the functionalities of ginseng, an acid impregnation pre-treatment was applied during red ginseng processing. Acetic, ascorbic, citric, malic, lactic, and oxalic acid were used for the acid impregnation treatment, and total and crude saponin concentrations and ginsenoside patterns were evaluated. Total and crude saponin contents of red ginseng pre-treated by acetic, ascorbic, and citric acid were similar to those of red ginseng without pre-treatment, whereas lactic, malic, and oxalic acid pre-treatment caused a reduction of total and crude saponin in red ginseng. From the high performance liquid chromatography analysis of ginsenosides, increased Rg₃ density was shown in red ginseng pre-treated by acetic, ascorbic, and citric acid impregnation. In the case of lactic, malic, and oxalic acid pre-treatment, increased Rg₁ density was observed in red ginseng. Increased Rg₁ and Rg₃ contents due to acid impregnation during red ginseng processing may contribute to improving bioactive functionalities of red ginseng.