Earticle

To determine the chemopreventive potential of alyssin and iberin, the in vitro anticancer activities and molecular targets of isothiocyanates (ITCs) were measured and compared to sulforaphane in hepatocellular carcinoma cell HepG2. The SR-FTIR spectra observed a similar pattern vis-a-vis the biomolecular alteration amongst the ITCs-treated cells suggesting a similar mode of action. All of the ITCs in this study cause cancer cell death through both apoptosis and necrosis in concentration dependent manner ($20-80{\mu}M$). We found no interactions of any of the ITCs studied with DNA. Notwithstanding, all of the ITCs studied increased intracellular reactive oxygen species (ROS) and suppressed tubulin polymerization, which led to cell-cycle arrest in the S and $G_2/M$ phase. Alyssin possessed the most potent anticancer ability; possibly due to its ability to increase intracellular ROS rather than tubulin depolymerization. Nevertheless, the structural influence of alkyl chain length on anticancer capabilities of ITCs remains inconclusive. The results of this study indicate an optional, potent ITC (viz., alyssin) because of its underlying mechanisms against hepatic cancer. As a consequence, further selection and development of effective chemotherapeutic ITCs is recommended.

Cyanoacrylate glues are quick setting materials which rapidly cure to hard, clear glassy resins. Its synthesis too has not been reported in the open literature so far. Synthetic methods, which engage esterification of cyanoacetic acid with a preferred alcohol, polymerization by knoevenagel condensation and successive depolymerization, are applied to the synthesis of lower membered alkyl cyanoacryaltes in which the alkyl groups carry less than 8 carbons. We have synthesized 1-octyl cyanoacetate by a traditional method involving p-toluene sulphonic acid as the catalyst. In the second step, we have attempted the preparation of poly (n-octyl cyanoacrylate) by the reaction of formaldehyde with n-octyl-2-cyanoacetate in the presence of both piperidine and potassium carbonate in the absence of any solvents. Its FTIR spectrum confirmed its functional groups: Its –OH stretching yielded a broad band around 3400 cm-1. The polymer was depolymerized using poly phosphoric acid catalyst under vacuum to obtain the monomer. A simple method of obtaining monomer was also attempted by the reaction of 1-octyl- 2-cyano acetate and diiodomethane in the presence of potassium carbonate. This process directly yields the monomer. The second method looks better than the others, and it can be applied to any type of alcohols.

This study evaluated the effects of γ-irradiation on immunomodulating properties and structural changes of β-glucan. β- Glucan solutions (10 mg/mL) were γ-irradiated at 10, 30, and 50 kGy. Splenocyte proliferation and cytokine (interferon-γ and interlukin-2) productions by γ-irradiated β-glucan were evaluated in in vivo and in vitro, and structural changes of β-glucan were also determined after γ-irradiation. γ-Irradiation on β-glucan at 50 kGy enhanced splenocyte proliferation and cytokine productions, (p<0.05) and cleft glycosidic bonds of β-glucan resulting in lower the molecular weight. These results indicate that the use of γ- irradiation on β-glucan may be useful for improving its immunological activity by lowering the molecular weight of β-glucan.

Alginates are quite abundant as a major structural component and as the complex polysaccharide comprising up to 40% in brown seaweed (Phaeophyceae). To obtain monomeric sugar and other derivatives from alginate, it must be prepared by break down the polysaccharide structure into simple monosaccharide. Therefore, to produce the appropriate monomeric sugar and other compounds, depolymerization treatment of alginate is needed. The depolymerization concept of alginate will be done on raw brown seaweed and brown seaweed with catalyst added by subcritical water treatment. The experiment condition will be performed at 180 to 260 oC for the reaction temperatures and 1.0 to 5.5 MPa for the pressures. The ratio of material to water is 1:25 (w/v) and the reaction time of each condition will be maintained for 5 min. Analysis of monomeric sugar dissolved on hydrolysate water will be assessed by HPLC (High Performance Liquid Chromatography). The total organic carbon contained will be measured by Total Organic Carbon (TOC) analyzer. Total reducing sugar will be conducted using method from Miller (1959).

An alginate lyase from Pseudomonas sp. KS408 was cloned and characterized. Recombinant E. coli harvested with alginate gene was expressed by IPTG induction and purified by using Ni-Sepharose affinity chromatography. Alginate oligomers obtained by degrading alginate with KS408 alginate lyase were analized by using FPLC and H-NMR. Peak profile from NMR showed that KS408 alginate lyase was polyM-specific lyase (β1-4 lyase, EC4.2.2.3). KS408 alginate lyase could cleavage between D-b-mannuronate and D-b-mannuronate linkage (MM) not D-b-mannuronate and L-α-guluronate linkage (MG). The molecular weight of oligoalginate products also analyzed with Electron-spray-ionization/Mass spectroscopy (ESI-MS). When polyM block was treated with KS408, four part of dimer and 1 part of trimer could be obtained. Acknowledgement : This work was supported by New &Renewable Energy R&D program(20093020090020) under the Korea Ministry of Knowledge Economy(MKE) and Korea Industrial Technology Foundation (KOTEF) through the Human Resource Training Project for Strategic Technology.

Deploymerization and liquid phase radical oxidation was conducted with water soluble cellulose such as methyl cellulose(MC), carboxy methyl cellulose(CMC), hydroxypropyl methyl cellulose(HPMC), hydroxyethyl cellulose(HEC) with the hydrogen peroxide and iron ions in the rotary evaporator by controlling the pressure and temperature. From the each compouds many volatile carbons, such as formed and major product is methanol through the GC-MS analysis. Polymer methyl-cellulose deploymerized with hydrogen peroxide and iron ions into oligomer, glucose, xylose and organic acid such as succinic acid and acetic acid through the low temperature reaction (25℃, 6hr) and and gluco-pyranose and methanol prepared mainly after heated 150 ℃ in the batch reactor 4 hours.The glucose pyranose could be utilized as subtracts for fermentation for ethanol after radical removed by radical scavenger such as hydro quinone and ascobic acid

Various factors affecting yields of Gal, AG, and 5-HMF formationduring saccharification were investigated using agar as a substrate in the presence of several bisulfate-based acidic ionic liquids as catalysts. The result was compared with employing sulfuric acid in saccharification from the viewpoint of sugar yields and 5-HMF formation. [Bmim][HSO4], [Hmim][HSO4], [Morph][HSO4], [Bu4N][HSO4], [Bu4P][HSO4], [Chol][HSO4] showed moderate to high yields of Gal and AG with a remarkable decrease in 5-HMF formation compared with sulfuric acid. Among them, [Chol][HSO4] ionic liquid was found to exhibit the highest yield of sugars with an acceptable concentration of 5-HMF that does not inhibit the fermentation process.

본 연구에서는 대추를 필름 형태의 식품 소재로 개발하였다. 대추 필름 제작에 고분자 분쇄 방법으로 사용된 HPH는 대추 필 름의 인장 강도와 수분 투과도를 향상시켰다. 기존에 개발된 많 은 다른 생고분자 필름보다 높은 인장 강도와 낮은 수분 투과도 는 열접합강도와 함께 식품에 있어 HPH 대추 필름의 상업적 적 용 가능성을 보여주었다. 대추 필름은 대추 고유의 형태와 크기 에 제한 없이 여러 식품에 코팅 또는 롤 형태로 사용될 수 있을 것으로 기대된다.

Edible films were developed from jujube (Zizyphus jujube Miller) using depolymerization processes of ultrasound and high-pressure homogenization. A 4.6% (w/w) jujube hydrocolloid was treated by ultrasound (600W, 20 min) or homogenized at high pressure (172 MPa, 6 s) and mixed with whey protein isolate, glycerol, xanthan, and sucrose esters of fatty acids to form film-forming solutions from which films were formed by drying. The film prepared by highpressure homogenization (HPH film) produced more homogeneous films without particles than those prepared without depolymerization or with the ultrasound treatment. HPH films possessed the highest tensile strength (4.7MPa), the lowest water vapor permeability (2.9 g·mm/kPa·h·m2), and the most uniform and dense microstructures among the films. Flavor profiles of jujube powder and the films were distinguishable. Heat seal strength and oxygen permeability of the HPH films were 44.4 N/m and 0.025 mL·μm/m2/day/Pa, respectively. Antioxidant activities of jujube power and HPH films were not significantly different.

The nascent thyroglobulin (Tg) multimer molecule, which is generated during the initial fate of Tg in ER, undergoes the rapid reductive depolymerization. In an attempt to determine the depolymerization process, various types of Tg multimers, which were generated from deoxy­cholate-treated/reduced Tg, partially unfolded Tg or partially unfolded/reduced Tg, were subjected to various GSH (reduced glutathione) reducing systems using protein disulfide isomerase (PDI), glutathione reductase (GR), glutaredoxin or thioredoxin reductase. The Tg multimers generated from deoxycholate-treated/reduced Tg were depolymerized readily by the PDI/GSH system, which is consistent with the reductase activity of PDI. The PDI/GSH-induced depolymerization of the Tg multimers, which were generated from either partially unfolded Tg or partially unfolded/reduced Tg, required the simultaneous inclusion of glutathione reductase, which is capable of reducing glutathionylated mixed disulfide (PSSG). This suggests that PSSG was generated during the Tg multimerization stage or its depolymerization stage. In particular, the thioredoxin/thioredoxin reductase system or glutaredoxin system was also effective in depolymerizing the Tg multimers generated from the unfolded Tg. Overall, under the net GSH condition, the depolymerization of Tg multimers might be mediated by PDI, which is assisted by other reductive enzymes, and the mechanism for depolymerizing the Tg multimers differs according to the type of Tg multimer containing different degrees and types of disulfide linkages.

Hydroxyl raical$(OH{\cdot})$을 생성하는 것으로 알려진 iron-catalyzed Haber-Weiss rocation에서 superoxide anion $(O^{-}_{2}{\cdot})$은 주로 $Fe^{+++}$을 $Fe^{++}$로 환원시키는 데에 작용하는 것으로 추정하고 있다. 이러한 $OH{\cdot}$ 의 역할은 다른 환원제들에 의하여 대체가 가능할 것으로 추측되며 생물계의 환원제의 하나로써 ascorbate가 관심의 대상이 되고 있다. 이에 따라 본 연구에서는 $Fe^{++}$와 $H_2O_2$ 존재하에서 $OH{\cdot}$ 을 생성하는 ascorbate 의 역할을 hyaluronic acid의 변성과 methional로 부터 ethylene 생성에 대한 효과로써 관찰하였다. Ascorbate는 $Fe^{++}$와 $H_2O_2$에 의한 hyaluronic acid의 변성을 촉진하였으며, 이런 현상은 점성도 변화와 Sepharose 4B를 이용한 코로마토그라피에 의하여 확인할 수 있었다. 이때 관찰되는 변성은 catalase와 $OH{\cdot}$ scavenger에 의하여 거의 완전히 억제 되었다. 또한 ascorbate는 $Fe^{++}$와 $H_2O_2$에 의한 methional로 부터 ethylene생성을 항진시킴으로써 상기의 결과를 뒷받침 하였다. 다른 환원제들(cysteine, glutathione, NADH와 NADH와 NAKPH)도 ascorbate와 같이 hyaluronic acid의 변성과 methional로 부터 ethylene생성을 촉진하였으나, 그들의 산화형인 NAD와 NADP의 효과는 관찰 할 수 없었다. 그러므로 $OH{\cdot}$ 생성에 있어 철이온의 환원이 관여함을 시사하였다. 또한 metal ion가운데 $Fe^{++}$는 $OH{\cdot}$ 생성에 가장 강력한 촉매작용을 나타내었다. 이상의 결과는 ascorbate가 $(OH{\cdot})$ 을 생성하는 metal-catalyzed reaction에서 $Fe^{+++}$을 $Fe^{++}$로 환원하는 $O^{-}_{2}{\cdot}$의 작용을 대신할 수 있음을 증명하며 이와같은 ascorbate 의존적인 $OH{\cdot}$ 의 생성은 ascorbate가 조직손상에 관여할 가능성을 시사하였다.

In tile Iron-catalyzed Haber-Weiss reaction to produce OH., the requirement for $O^{-}_{2}{\cdot}$ is only to reduce $Fe^{+++}$. Possibly, the role of $O^{-}_{2}{\cdot}$ can be replaced by other reducing agents. Ascorbate is one of them in biological system. In the present study, the ability of ascorbate to produce $OH{\cdot}$ in the presence of $Fe^{++}$ and $H_2O_2$ was investigated by observing the degradation of hyaluronic acid and ethylene production from methional. Ascorbate stimulated the degradation of hyaluronic by $Fe^{++}$ and $H_2O_2$. That was confirmed by both viscosity change and gel-permeation chromatographic analysis. The observed degradation was almost completely prevented by catalase and $OH{\cdot}$ scavengers. In support of the above results, ascorbate enhanced the prouction of ethylene from methional in the presence of $Fe^{++}$ and $H_2O_2$. Other reducing agents (cysteine, glutathione, NADH and NADPH) showed similar activities to ascorbate in the degradation of hyaluronic acid and ethylene production. But no stimulatory effects were observed with their oxidized forms such as NAD and NADP. Thus, it appears that reduction of the metal ion was needed for $OH{\cdot}$ production. Among the metal ions tested, $Fe^{++}$ showed most potent catalytic action in the production of $OH{\cdot}$ The results obtained support that ascorbate can substitute $O^{-}_{2}{\cdot}$ in the metal-catalyzed reactions, particularly with $Fe^{++}$ by which $OH{\cdot}$ is produced with $H_2O_2$. The significance of the ascorbate-dependent production of $OH{\cdot}$ was considered with respect to possible role of ascorbate in the damage of inflamed joints.

펄프 및 제지산업에서 목재의 셀룰로오스 성분 활용 후 남는 부산물인 크라프트 리그닌(kraft lignin)은 촉매적 저분자화 공정을 통해 바이오연료나 고부가가치 페놀 단량체로 전환될 수 있다. 본 연구에서는 크라프트 리그닌의 효율적인 저분자화를 위한 촉매로 수소화 금속 및 산-염기점을 동시에 지니는 Ru-Mg-Al-oxide 복합 촉매를 제조하고, 리그닌 분해 성능을 평가하고자 하였다. 촉매 내 다양한 활성점들(산점, 염기점, 수소화 금속)이 리그닌 분해 반응에 미치는 영향을 파악하기 위해 MgO, Mg-Al-oxide, Ru-Mg-Al-oxide의 세 가지 촉매를 제조하여 초임계 에탄올 용매 상에서 리그닌 분해 반응을 수행하였고, 리그닌 분해 성능은 바이오오일(bio-oil) 수율 및 분자량, 그리고 페놀계 단량체 수율을 통해 평가하였다. 그 결과, Ru-Mg-Al-oxide 촉매가 다양한 활성점들의 시너지 효과로 인해 가장 높은 수율의 바이오오일 및 페놀 단량체들을 생산한다는 것을 확인하였다. Ru-Mg-Al-oxide 촉매 상에서 분해 효율을 최적화하기 위해 다양한 반응 조건(온도, 시간, 촉매양)에 따른 분해 효율을 평가하였고, 최종적으로 반응온도 350 ℃, 리그닌 대비 촉매 비율 10%, 4 h 반응을 통해 72%의 높은 바이오오일 수율과 무촉매 대비 3.5배 이상 증가한 페놀 단량체를 생산할 수 있었다.

Kraft lignin is a by-product of the pulp and paper industry, obtained as a black liquor after the extraction of cellulose from wood through the Kraft pulping process. Right now, kraft lignin is utilized as a low-grade boiler fuel to provide heat and power but can be converted into high-calorific biofuels or high-value chemicals once the efficient catalytic depolymerization process is developed. In this work, the multi-functional catalyst of Ru-Mg-Al-oxide, which contains hydrogenation metals, acid, and base sites for the effective depolymerization of kraft lignin are prepared, and its lignin depolymerization efficiency is evaluated. In order to understand the role of different active sites in the lignin depolymerization, the three different catalysts of MgO, Mg-Al-oxide, and Ru-Mg-Al-oxide were synthesized, and their lignin depolymerization activity was compared in terms of the yield and the average molecular weight of bio-oil, as well as the yield of phenolic monomers contained in the bio-oil. Among the catalysts tested, the Ru-Mg-Al-oxide catalyst exhibited the highest yield of bio-oil and phenolic monomers due to the synergy between active sites. Furthermore, in order to maximize the extent of lignin depolymerization over the Ru-Mg-Al-oxide, the effects of reaction conditions (i.e., temperature, time, and catalyst loading amount) on the lignin depolymerization were investigated. Overall, the highest bio-oil yield of 72% and the 3.5 times higher yield of phenolic monomers than that without a catalyst were successfully achieved at 350 ℃ and 10% catalyst loading after 4 h reaction time.

전자빔조사와 과산화수소를 사용하여 알지네이트(sodium alginate, SA)를 저분자화 시키는데 1.0, 2.5 MeV의 전자빔 에너지가 이용되었으며, 저분자화 수율($G_s$), 분자량의 제어를 위해 2.5 ~ 20 kGy의 조사량, 0 ~ 4.5%의 과산화수소의 양을 조절하였다. 전자빔조사에 의한 저분자화 알지네이트(depolymerized sodium alginate, DSA)는 주로 1,4-glicoside결합이 끊어지며, C2-C3결합이 끊어지며 생기는 약간의 formate 말단을 가지며, 전자빔 조사 저분자화 저분자 알지네이트 말단(end group)의 화학적 구조가 단순하며, 고분자 알지네이트와 유사한 구조를 가짐을 알 수 있었다. 도입된 전자빔의 에너지와 조사량이 증가하면 알지네이트의 분자량은 감소하였으며, 알지네이트의 농도(2.0w/v%)로 높을 때 저분자화수율이 높았다. 특히 2% 알지네이트 수용액에 20 kGy (2MeV)의 조사량과 1.5% 과산화수소를 도입하였을 때 가장 큰 저분자화 수율($7.919{\times}10^4mol/J$)을 얻을 수 있었다.

Depolymerization of sodium alginate (SA) was carried out by electron beam irradiation in a hydrogen peroxide atmosphere. E-beam with 1.0 and 2.5 MeV of accelerating voltages were employed in this experiment. For control of molecular weight and the radiation yield of scission ($G_s$), the irradiation dosage of e-beam was managed in a range from 2.5 to 20 kGy while the quantity of hydrogen peroxide was adjusted in a range of 0 to 4.5%. The chemical structure of the depolymerized sodium alginate (DSA) was analyzed to have scission of 1,4-glycoside bond mainly and a few fragmentary formate end groups which may be produced by the cleavage between C2 and C3 in repeating unit of alginate. It turned out to have simple chemical structures at the DSA end groups, produced by e-beam irradiation, similar with those in the polymer SA structure. As a result, the molecular weight of SA decreased as the energy and dosage of applied e-beam increased, and the radiation yield of scission showed the best result at 2w/v% in SA concentration. The highest radiation yield of scission ($7.919{\times}10^4mol/J$) was confirmed when an irradiation dosage of 20 kGy (2 MeV) and 1.5% hydrogen peroxide were used in 2% SA aqueous solution.

식물계 바이오매스는 석유로부터 얻어지는 화학물질들을 대체할 수 있는 물질로 제안되고 있다. 특히 식물계 바이오매스의 15-30%를 이루고 있는 리그닌은 복잡한 방향족 중합체로 이루어져 있어, 리그닌의 저분자화 공정에 의해 다양한 방향족 화합물을 얻을 수 있다. 본 연구에서는 국내에서 가장 많이 배출되는 크래프트 리그닌을 출발 물질로 선정하고, $^{13}C$-Muclear Magnetic Resonance($^{13}C$-NMR), Fourier Transform Infrared Spectroscopy (FT-IR), Elemental Analysis(EA)을 통해 원료물질의 화학적 구조를 분석하였다. 크래프트 리그닌의 저분자화 는 물-페놀 혼합 용매의 근임계 영역에서 수행되었으며, tube bomb reactor를 사용하였다. 최적의 반응조건을 찾기 위해 물-페놀의 비율, 반응온도($300-400^{\circ}C$)를 변화시키며 실험을 수행하였다. 또한 기체상 수소를 대신하여 수소발생 용매인 formic acid 사용에 따른 영향을 조사하였다. 액상 생성물의 화학 종류 및 양은 GC-MS를 통해 분석하였고, 고체 잔류물(char)은 FT-IR을 통해 분석하였다. GC-MS 분석 결과 페놀이 첨가된 경우 anisole, o-cresol(2-methylphenol), p-cresol(4-methylphenol), 2-ethylphenol, 4-ethylphenol, dibenzofuran, 3-methyl cabazole, xanthene이 생성되는 것을 확인하였다.

Plant biomass has been proposed as an alternative source of petroleum-based chemical compounds. Especially, aromatic chemical compounds can be obtained from lignin by depolymerization processes because the lignin consist of complex aromatic materials. In this study, kraft lignin, the largest emitted substance among several kinds of lignin in Korea, was used as a starting material and was characterized by solid-state $^{13}C$-Muclear Magnetic Resonance($^{13}C$-NMR), Fourier Transform Infrared Spectroscopy(FT-IR), Elemental Analysis(EA). The depolymerization of kraft lignin was studied at water-phenol mixture solvent in near critical region and the experiments were conducted using a batch type reactor. The effects of water-to-phenol ratio and reaction temperature($300-400^{\circ}C$) were investigated to determine the optimum operating conditions. Additionally, the effects of formic acid as a hydrogen-donor solvent instead of $H_2$ gas were examined. The chemical species and quantities in the liquid products were analyzed using gas chromatography-mass spectroscopy(GC-MS), and solid residues(char) were analyzed using FT-IR. GC-MS analysis confirmed that the aromatic chemicals such as anisole, o-cresol(2-methylphenol), p-cresol(4-methylphenol), 2-ethylphenol, 4-ethylphenol, dibenzofuran, 3-methyl cabazole and xanthene were produced when phenol was added in the water as a co-solvent.

본 연구에서는 촉매 존재 하에서 에틸렌글리콜(EG)를 이용하여 글리콜리시스를 통해 PET(Poly ethylene terephthalate)을 해중합하여 BHET(bis-hydroxyethyl terephthalate)를 얻기 위한 방법에 대하여 연구하였다. 촉매는 zinc acetate가 사용되었고, 생성물은 high performance liquid chromatography(HPLC)으로 분석하였다. 반응 시간, 반응 온도, EG양과 같은 조건들의 영향을 알아보았으며, 반응 속도식을 구하였다. 그 결과 반응 온도와 반응 시간이 증가함에 따라 BHET의 수율과 해중합 속도는 증가하였지만, 너무 높은 반응 온도 $250^{\circ}C$에서는 BHET가 중합반응을 일으켜 $230^{\circ}C$ 보다 수율이 낮게 나타났다. 1차 반응속도 모델을 가정하여 반응 활성화에너지를 구하였다. 얻어진 활성화 에너지는 $210^{\circ}C$ 이상과 $210^{\circ}C$ 이하에서 각각 37.8, 149.6 kJ/mol이었다. 이는 이 반응이 다단 연속 반응임을 보여준다. BHET의 최대 수율은 반응 온도 $230^{\circ}C$, 반응 시간 6시간 그리고, EG/PET의 비율이 4일 때 가장 높은 71%의 수율을 나타내었다.

A method for depolymerization of PET by catalyzed glycolysis with an excess ethylene glycol(EG) to recover bis-hydroxyethyl terephthalate(BHET) was investigated. The product was analyzed by high-performance liquid chromatography(HPLC). Effects of operation variables such as reaction temperature, reaction time, EG/PET weight ratio were examined and kinetics of the glycolysis was studied. High temperature increases the rate of depolymerization and the yield of BHET. But, repolymerization rate was also high at too high temperature and the yield at $250^{\circ}C$ was shown to be lower than that at $230^{\circ}C$. First order reaction model was proposed to describe the glycolysis reaction. Activation energies for the reaction were obtained to be 37.8 kJ/mol above $210^{\circ}C$ and 149.6 kJ/mol below $210^{\circ}C$, which shows the glycolysis reaction is a multiple reaction. A maximum yield of BHET of 71% was achieved at a reaction temperature of $230^{\circ}C$ for 6 hr with an EG/PET weight ratio 4.

본 연구에서는 촉매를 사용하지 않고 에틸렌글리콜(EG)을 이용하여 비스페놀 A(BPA)를 얻기 위한 폴리카보네이트(PC) 해중합 방법에 대하여 연구하였다. 반응시간, 반응온도, 에틸렌글리콜 양에 따른 비스페놀 A의 수율에 대하여 알아 보았으며, 반응속도식을 구하였다. 에틸렌글리콜에 의한 해중합 반응은 반응 온도에 따라 활성화 에너지가 높은 쪽에서 낮은 쪽으로 변하였고, 이는 이 반응이 여러 단계의 직렬반응으로 이루어진 것을 나타낸다. 비스페놀 A의 최대수율은 EG/PC 무게비 4, 반응온도 $220^{\circ}C$, 반응시간 85분에서 95.6%였다.

A method for the depolymerization of polycarbonate waste by glycolysis using ethylene glycol without catalyst was explored in order to get the monomer bisphenol A (BPA). The effect of operation variables such as reaction time, reaction temperature, EG/PC weight ratio and the kinetic of glycolysis were studied. It was found that the polymerization reaction has two different activation energies depending on the reaction temperature. A drop in activation energy with temperature indicates that the reaction mechanism has shifted from one of a succession of elementary steps to another in the series. The maximum yield of BPA of 95.6% was achieved at reaction temperature $220^{\circ}C$ for 85min with EG/PC weight ratio 4.

온화한 조건($80{\sim}110^{\circ}C$, 대기압)하에서 비누화반응에 의해 폐 PBT의 입자를 해중합하여다. PBT의 해중합은 KOH 보다 NaOH가 보다 효과적이었으며, 반응온도가 증가하고 입자의 크기가 작을수록 해중합은 증가하였다. 해중합속도는 표면반응이 율속단계로서 PBT 입자표면에 생성물이 형성되지 않은 미반응핵 모델에 의해 표현할수 있었다. 겉보기활성화에너지는 98.1KJ/mol 이었으며, 85.1, $105{\mu}m$인 PBT 입자를 6시간 동안 해중합하였을때 TPA의 회수율은 약 95%정도였다.

Waste PBT powder was depolymerized by saponification under the mild temperature conditions($80{\sim}110^{\circ}C$) and atmospheric pressure. In depolymerization of PBT, sodium hydroxide was more effective than potassium hydroxide. The depolymerization increased with increasing reaction temperature and decreasing particle size. The reaction kinetics of depolymerization could be expressed by the shrinking unreacted core model without product layer, in which the surface reaction was a rate determining step. The activation energy was 98.1 KJ/mol. The recovery ratio of the TPA obtained from the depolymerized PBT particles of 85.1 and $105{\mu}m$ for 6 hours was about 95%.

Resource recovery and recycling of materials and products, including polyurethanes is viewed as a necessity in today's society. Most urethane polymers are made from a polyol and a diisocyanate. these and be chemicals such as water, diamines or diols that react with isocyanate groups and add to the polymer backbone. The problems of recycling polyurethane wastes has major technological, economic and ecological significance because polyurethane itself is relatively expensive and its disposal whether by burning is also costly. In general, the recycling methods for polyurethane could be classified as mechanical, chemical and feedstock. In the chemical recycling method, there are hydrolysis, glycolysis, pyrolysis and aminolysis. This study, the work was carried out glycolysis using sonication ant catalyzed reaction. Different kinds of recycled polyols were produced by current method(glycolysis), catalyzed reaction and sonication as decomposers and the chemical properties were analyzed. The reaction results in the formation of polyester urethane diols, the OH value which is determined by the quantity of diol used for the glycolysis conditions. The glycolysis rates by sonication for the various glycols, increased as fallows: PPG <PEG < DEG < EG. The recycled polyol of sonication reaction had much higher OH value, much lower decomposition temperature and time than the recycled polyol of current method in which same glycols and catalyst were used.