라디칼 회분식 반응 공정을 사용하는 있는 중 소규모 화학공장의 경우, 취급 물질, 작업 내용 및 제품 등의 여러가지 상황 변화에 따른 잠재적인 화재, 폭발 및 안전의 위험성이 상존해 있다. 이러한 화학공장에서 마주치는 잠재적인 위험성에 대하여, 정성적인 위험성 평가 및 분석을 위하여 대표적으로 많이 사용되는 평...

Carbon master batch (CMB) rubber sheets, which are stored in stacks, are difficult to separate during reuse because of the adhesion between sheets caused by the stacked weight over time. To solve this problem, in the actual rubber product manufacturing process, various anti-tacking agents (solid powder or liquid surfactants) are applied to the sheet surface. In this study, the emulsion samples of zinc (Zn)-stearate/triethanolamine (TEA)-stearate mixtures were prepared using TEA-stearate as a surfactant, prepared using an industrially manufactured Zn-stearate powder, and their basic anti-tacking properties were studied. During the process of manufacturing emulsion, a heat treatment process and an auxiliary surfactant were introduced to improve the dispersion stability. Results showed that the heat-treated sample exhibited a significant improvement in terms of sedimentation, storage stability, and anti-tacking characteristics since the Zn-stearate particles were reduced to a smaller size by the heat-treatment than that of the original Zn-stearate powder.

Risk assessment and analysis for a medium-to-small sized chemical plant that manufactures a polyester resin by the process of batch-type condensation reaction was conducted using K-PSR technique which is one of the risk assessment methods used to implement the Process Safety Management System (PSM). K-PSR is a risk assessment technique developed by KOSHA to compensate for difficulties caused by the lack of infrastructure of medium-to-small sized chemical plants in the re-evaluation. To apply the K-PSR technique, the entire process of a selected chemical palnt was classified in two review sections, i.e., the condensation reaction process and the dilution/filtration process, and the potential risks of the process about these review sections were identified and classified based on the four guide-words (release, fire.explosion, process trouble, and injury). As the results of the research, refer to recommend of risk rating has been confirmed that non-destructive testing of old facilities and the preparation of LOTO procedures for the electrical equipments are necessary as specific measures to prevent the risk of release and fire·explosion. It was also shown that pressure gauges and thermometers should be installed on the hot-oil supply piping to minimize the process trouble, and exhausting hood should be installed to prevent potential injury.

The present study examines the transformation of dynamic DSC data into the equivalent isothermal data for the formation kinetics of a polyurethane elastomer. The reaction of 2'-dichloro-4,4'-methylenedianiline (MOCA) with a PTMG/TDI-based isocyanate prepolymer was evaluated. DSC measurement was performed in the dynamic scanning mode with several different heating rates to obtain the reaction thermograms. Then, the data was transformed into the isothermal data through a procedure based on Ozawa analysis. The main feature of this procedure was the transformation of (alpha-T)(beta) curves from dynamic DSC into (alpha-t)(T) curves using the isoconversional (t-T)(alpha) diagram. Validity was discussed for the relationship between the dynamic DSC data and the transformed isothermal results.

Cell opening characteristics of a polyurethane foam (PUF) with conventional formulation for a closed-cell rigid PUF was studied using lithium salt of 12-hydroxystearic acid (Li-121-JSA) as a cell-opening agent. The cell-opening agent, Li-12HSA, was properly prepared in the surfactant silicone oil, in which it existed as uniformly distributed in nanoscale. Cell opening content of nearly 100% could be obtained for the sample with ca. 1.0 phr of Li-12HSA. As the results, it showed that a fully open-cell rigid PUF could be obtained by introducing Li-12HSA as a new reactive cell opener, having a functional group which is able to form a bulky flexible side-chain on PU main chains. Furthermore, the formed open cell rigid PUF showed desirable cell size, bulk density, and thermal conductivity without severe loss of mechanical properties compared to those of the closed-cell PUF which was made without Li-12HSA.

In the current research, the curing kinetics of a mixture system consisting of a Bisphenol-A type vinyl ester resin and styrene monomer was studied. Methylethylketone peroxide and cobalt octoate were used as the polymerization initiator and accelerator respectively. Thermograms with several different heating rates were obtained using non-isothermal differential scanning calorimetry. Activation energy values analyzed by the Flynn-Wall-Ozawa isoconversional method showed a three-step change with conversion α: a slight decrease initially for α < 0.1, a constant value of 47.9 kJ/mol in the range 0.1 < α < 0.7, and a slow increase for 0.7 < α. When assuming a constant activation energy of 47.9 kJ/mol, an autocatalytic model of the Sestak-Berggren equation was considered as the proper mathematical model of the conversion function, indicating an overall order of 1.2.

The tensile strength (TS) and elongation-at-break (EB) loss of a CR/CB rubber composite sample prepared for the automotive parts were measured after accelerated thermal ageing at temperatures of 100, 120, 140, and 150 degrees C. The change in TS was observed to be linear from the master curve prepared using the time-temperature superposition-principle (TTSP). An Arrhenius type of shift factor, a(T) was used to predict the life time of the sample, and a plot of ln a(T) vs. 1/T was also shown to be linear. The activation energy (E-a) of the sample was calculated as 70.30 kJ/mole from the Arrhenius plot. The expected life time of the sample was predicted at the given operating conditions by applying Arrhenius analysis. Assuming the E-a value was constant at lower operating condition, life time of the sample was calculated as 2.3 years when the life limit was set as time to reach the 20% decrease of the initial TS value at operating temperature of 40 degrees C.

Thermal decomposition kinetics for two different types of polyurethane elastomers prepared with 2,2'-dichloro4,4'- methylenedianiline (MOCA) and 3,5-dimethyl-thiotoluenediamine (Ethacure-300), based on PTMG/TDI isocyanate prepolymer, were studied using non-isothermal thermogravimetric analysis (TGA). Thermograms were obtained and analyzed using Friedman (FR) and Kissinger-Akahira-Sunose (KAS) methods for activation energy, E-a. The results obtained showed that decomposition reaction of both samples was observed similarly to occur through three different stages, i.e., initial stage with vaporization of low molecular weight materials, second stage of urethane linkage decompositions, and later stage of polyol segment decompositions. However, activation energy values at each stage for the sample cured with Ethacure- 300 was much lower than those for the sample with MOCA, exhibiting relatively lower thermal stability for the sample with Ethacure-300 than that with MOCA.

For improving the heat loss of a refrigerator around door gasket, it is very important to reduce the amount of rubber magnet used, of which thermal conductivity is much higher than the plastics, and enhancing the magnetic properties of rubber magnet itself is crucial for this. In the present study, therefore, a relationship between the optimum conditions of rubber magnet fabrication process and raw material compositions in the ferrite powder/CPE binder compounds was investigated for finding a way to enhance the magnetic properties of rubber magnet. Magnetic attraction forces of a sample rubber magnet was measured as function of distance, and thermal properties of the sample ferrite powder/CPE binder compound were analyzed with TG/DTA thermal analyzer. As a results, a rubber magnet strip with enhanced magnetic properties was expected to be fabricated, of which raw material compound was prepared by compounding with higher ferrite magnetic powder concentration.

The effects of MWCNT on the cell sizes, cell uniformities, thermal conductivities, bulk densities, foaming kinetics, and compressive mechanical properties of the rigid PUFs were investigated. To obtain the better uniform dispersed state of MWCNT, grease-type master batch of MWCNT/surfactant was prepared by three-roll mill. Average cell size of the PUF samples decreased from 185.1 for the neat PUF to 162.9 μm for the sample of 0.01 phr of MWCNT concentration. Cell uniformity was also enhanced showing the standard cell-size deviation of 61.7 and 35.2, respectively. While the thermal conductivity of the neat PUF was 0.0222 W/m(o)K, that of the sample with 0.01 phr of MWCNT showed 0.0204 W/m(o)K, resulting 8.2% reduction of the thermal conductivity. Bulk density of the PUF samples was observed as nearly the same values as 30.0 ± 1.0 g/cm3 regardless of MWCNT. Temperature profiles during foaming process showed that an indirect indication of the nucleation effect of MWCNT for the PUF foaming system, showing faster and higher temperature rising with time. The compressive yield stress is nearly the same as 0.030 x 10(5) Pa regardless of MWCNT.

【Thermo-mechanical treatment process of a compressed open-cell rigid polyurethane foam (OC-RPUF), which was fabricated for the vacuum insulation panel (VIP), was studied to obtain an optimum condition for the dimensional stability by the relaxation of compressive stress. Thermo-mechanical deformation of the sample OC-RPUF was shown to occur from about $120^{\circ}C$ . Yield stress of 0.36 MPa was shown at about 10% yield strain. And, densification of the foam started to occur from 75% compressive strain and could be continued up to max. 90%. Compression set of the sample restored after initial compression to 90% at room temperature was ca. 82%. Though the expansion occurred to about twice of the originally compressed thickness in case of temperature rise to $130^{\circ}C$ , it could be overcome and the dimensional stability could be maintained if the constant load of 0.3 MPa was applied. As the result, a thermo-mechanical treatment process, i.e, annealing process at temperature of $130{\sim}140^{\circ}C$ for about 20 min as is the maximum compressed state at room temperature, should be required for dimensional stability as an optimum condition for the use of VIP core material.】

A study of the effects of MWCNT as a nucleating agent on the formation reactions of the rigid polyurethane foams (RPUFs) was carried out. Sample PUFs, formulated with grease-type master batch of MWCNT/surfactant, were fabricated by free-rising method. Temperature changes with time during foaming process were measured using a digital thermometer. RPUF foaming process was observed to undergo 2-step processes with temperature inflection around 60 sec after the start of reaction, and then reached slowly the max. temperature. While the max. temperature of neat PUF was measured as ca. 120 degrees C, that of the samples with MWCNT were as higher value as ca. 130 degrees C, and, even the time to reach that temperature was reduced by about 15 sec. Average cell size of PUF samples decreased from 185.1 for the neat PUF to 162.9 mu m for the sample of 0.01 phr of MWCNT. As the result, it was considered that MWCNT in RPUF foaming process could play a roll both as a nucleating agent and as a catalyst.

경질 폴리우레탄 폼(RPUF) 제조에서의 단열성 향상을 위하여 사용되는 PFA (Perfluoroalkane)는 액상의 발포 기핵제로서 성능은 뛰어나지만 매우 고가일 뿐만 아니라 불소화합물로서 환경 유해성 물질이다. 따라서 이를 대체할 수 있는 고성능의 대체 기핵제 개발에 대한 많은 연구가 진행되고 있다. 본 연구에서는 이에 대하여 다중벽 탄소나노튜브(MWCNT)를 고상 기핵제로 사용하여 제조한 샘플에서의 셀 크기 및 단열 성능과 기계적 물성에 미치는 영향을 비교 연구하여 보고자 하였다. 셀의 평균크기는 $165.6{\mu}m$에서 $162.9{\mu}m$로 상대적으로 더 작아졌으며, 표준 편차 역시 각각 45.6 및 35.2로서 상대적으로 더 균일한 셀 크기 분포를 가진 것으로 나타났다. k-factor 값 역시 0.01763 및 $0.01745kcal/m.hr.^{\circ}C$의 값으로서 1.02%가 감소된 더 작은 값을 나타내었다. 또한 압축 응력 시험에서의 초기 모듈러스는 상대적으로 더 큰 값을 나타내었으나 압축항복 응력은 약 $0.030{\times}105Pa$로서 거의 같은 값을 나타내었다. 이러한 결과들로 부터 MWCNT는 매우 우수한 기핵제로 작용함을 알 수 있었고, 따라서 소량의 MWCNT를 기핵제로 사용하여 경제적이면서도 우수한 단열효과와 기계적 물성을 지닌 친환경적인 경질 폴리우레탄 폼을 제조할 수 있음을 알 수 있었다. While perfluoroalkane (PFA), a liquid state nucleating agent for a rigid polyurethane foam (RPUF) to enhance the thermal insulation property, has the excellent nucleating characteristics, it is very expensive as well as environmentally harmful due to the fluoride compound. Many researches, therefore, have been performed to develop the alternative nucleating agents to replace PFA. In the present work, a multi-wall carbon nanotube (MWCNT) was used as a sloid state nucleating agent, and thereby the effects on the property changes of the RPUF were carried out. Average cell size decreased from 165.6 for base RPUF to $162.9{\mu}m$ and cell uniformity was also enhanced, showing the standard cell-size deviation of 45.6 and 35.2, respectively. While k-factor of base PUF was $0.01763kcal/m.hr.^{\circ}C$, that of the sample with 0.01 phr MWCNT showed 1.02% reduced value of $0.01745kcal/m.hr.^{\circ}C$. Though the compressive yield stress is nearly the same as $0.030{\times}105Pa$ for the both samples, initial modulus of the sample with 0.01 phr MWCNT was higher than that of base sample. it was considered as the results that small amount of MWCNT could play a sufficient role as the effective nucleating agent for RPUF, showing that an echo-friendly RPUF with reduced-cost could be fabricated, which has an enhanced thermal and mechanical properties.

A study on reaction kinetics for a PTMG/TDI prepolymer with 2,2'-dichloro-4,4'-methylenedianiline (MOCA), of which formulations may be generally used for fabricating high performance polyurethane elastomers, was peformed using non-isothermal differential scanning calorimetry (DSC). A number of thermograms were obtained at several constant heating rates, and analysed using Flynn-Wall-Ozawa (FWO) isoconversional method for activation energy, Ea and extended-Avrami equation for reaction order, n. Urea formation reaction of the present system was observed to occur through the simple exothermic reaction process in the temperature range of 100 similar to 130 degrees C for the heating rate of 3 similar to 7 degrees C/min. and could be well-fitted with generalized sigmoid function. Though activation energy was nearly constant as 53.0 +/- 0.5 kJ/mol, it tended to increase a little at initial stage, but it decreases at later stage by the transformation into diffusion-controlled reaction due to the increased viscosity. Reaction order was evaluated as about 2.8, which was somewhat higher than the generally well-known 2(nd) order values for the various urea reactions. Both the reaction order and reaction rate explicitly increased with temperature, which was considered as the indication of occurring the side reactions such as allophanate or biuret formation.

Fumed Silica와 섬유상의 Ceramic Wool을 사용하여 경량의 무기복합재 샘플을 제조하기 위한 조건과 만들어진 샘플의 단열특성을 살펴보았다. 정량된 Fumed Silica 미세분말과 Ceramic Wool을 혼합한 반죽을 몰드에 넣고 상온에서 안정화시킨 후에 $150^{\circ}C$ 오븐에서 완전히 건조하여 샘플을 제작하였다. 소량의 PVA 계면접착제를 사용하지 않는 샘플에서는 Fumed Silica 조성비가 10-70wt% 사이에서 벌크밀도가 0.6-0.8 $g/cm^3$이었으며, 50wt% 이상의 샘플에서는 건조 수축으로 인한 크랙현상이 관찰되었다. 그러나 3wt%의 PVA를 사용한 샘플의 벌크밀도는 절반 정도로 크게 감소하면서도 기계적 특성과 단열성은 향상되었다. 만들어진 샘플들은 $800^{\circ}C$ 이상의 고온에서도 열크랙 없이 안정한 열적 특성을 보여주었으며, 샘플의 단열성은 Fumed Silica 조성비가 높아질수록 향상되는 것으로 나타났다. Fumed Silica 30wt%인 샘플의 열전도도는 $500^{\circ}C$에서 약 0.08 $W/m^{\circ}K$의 우수한 단열 특성을 보여 주었다. This study examined the fabrication and thermal properties of fumed silica/ceramic wool inorganic composites. A predetermined quantity of fumed silica and ceramic wool was mixed uniformly into a slurry state and stabilized in the mold at room temperature, and converted to a massive foamed body through a complete drying process at $150^{\circ}C$. Although the samples without polyvinyl alcohol (PVA) as an interfacial adhesive showed a bulk density of 0.6-0.8 $g/cm^3$ in the range, 10-70wt% fumed silica, those samples with 3wt% PVA exhibited remarkably lower bulk densities with enhanced mechanical and thermal insulation properties, without thermal cracking even above $800^{\circ}C$. The K-factor of the samples was lower in proportion to the fumed silica contents, showing good thermal insulation properties of ca. 0.08 $W/m^{\circ}K$ at $500^{\circ}C$ for the sample with 30wt% fumed silica.

Compression set (CS) and weight loss by thermal degradation of the ACM rubber composite sample prepared for an automotive part were measured simultaneously at several given temperatures of 150 degrees C, 160 degrees C, 170 degrees C, and 180 degrees C. Using the relationship between them, thermal life of the sample could be predicted at a given operating temperature by applying Toops method which is based on the analysis of non-isothermal TGA thermograms. Conversion by weight loss showed a linear relationship with CS changes, exhibiting 4.2% at CS 40%. Activation energy of thermal degradation was calculated as 120.2 kJ/mol at 4.2% of weight loss from Flynn-Wall-Ozawa analysis. When the expected life was set as time to reach CS 40% at 120., the life time of the sample was calculated as 9,700 hrs when Toops method was applied.

$400^{\circ}C$의 고온에서 사용할 수 있는 무기단열재를 개발하기 위한 기초 연구로서 물유리(waterglass)를 바인더로 사용하여 제조한 팽창진주암(expanded perlite) 무기복합재의 단열성과 열 충격에 의한 크랙 방지에 관한 연구를 진행하였다. 정량된 팽창진주암 미세분말과 물유리를 혼합한 반죽을 몰드에 넣고 하루 동안 안정화시킨 후에 $150^{\circ}C$ 오븐에서 완전히 건조하여 샘플을 제작하였다. 인산알미늄(aluminum phosphate)와 마이카(mica)분말이 각각 반응촉진제와 열 충격 방지제로 사용되었다. 특히 마이카 분말이 도입된 샘플은 $500^{\circ}C$ 고온에서도 열에 의한 크랙 발생이 일어나지 않았으며, 샘플의 단열성은 팽창진주암의 혼합비율이 높아질수록 향상됨을 보여주었으며, 중량비로 물유리/perlite/mica/Al phosphate=100/200/10/1.5의 조성비를 같는 샘플은 $500^{\circ}C$에서 약 0.09W/mK의 열전도도를 나타내는 우수한 단열 특성을 나타내었다. 그러나 나트륨 실리케이트(sodium silicate)가 주성분인 물유리 바인더의 열적 특성으로 인하여 $600^{\circ}C$이상의 온도에서는 심한 치수변형을 발생시켜 실제 사용상의 온도 제한성을 보여 주었다. A study on the crack protection and thermal insulation properties of the expanded perlite inorganic composites was performed. Mixed expanded perlite with a water glass was stabilized for 24 hrs at room temperature in the mold and, thereafter, converted into a massive foamed body through complete drying process at $150^{\circ}C$. Aluminum phosphate and micron size mica powder were used as a reaction accelerator and a stabilizer for thermal crack, respectively. Especially, use of mica exhibited a remarkable effect on the protection of thermal crack at higher temperature over $500^{\circ}C$, and thermal conductivity of the composites was enhanced with higher perlite contents, showing ca. 0.09 W/mK for the sample of 100/200/10/1.5 water glass/perlite/mica/Al phosphate by weight. A severe dimensional deformation of the composite materials was observed over $600^{\circ}C$, however, showing a temperature limitation for a practical application. The facts were considered as the results from the glass transition temperature of the water glass, of which main component is sodium silicate.

Cell opening characteristics dependent on the cell openers for the conventional formulation of a closed-cell polyurethane foam (PUF) was studied using 1-butanol and lithium salt of 12-hydroxystearic acid (Li-12HSA) as the reactive cell opening agents. While cell openining content of only 10.5 % was obtained for the sample with 4 phr of 1-butanol as the single reactive cell opener, that of 98.0% could be obtained for the sample with 2 phr of Li-12HSA as the reactive co-cell opener. As the results, it showed that a fully open-cell rigid PUF could be obtained by introducing a novel reactive cell opener, having a functional group able to form a bulky side-chain on the urethane networks, without severe loss of mechanical properties of the closed-cell PUF like cell size, bulk density, and thermal conductivity.