• Polymer(Korea)
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• v.25 no.1
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• pp.142-150
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• 2001

Until now rubber industry field has used organic solvent base adhesive, there was always existed a fire risk, variety of quality and harmfulness of human body. To solve this problem we were developed a new adhesive that was maked by raw materials of hydrocarbon series which has the properties of nonvolatile and high flash point. Because of this new adhesive has the properties of nonvolatile and non-harmfulness to the human body, we expected to solve the problems of a fire hazard and the pollution of the environmental. Instead of the rubber binder that is used to a present adhesive, the new idea is adopted in a new type of adhesive. Nonvolatile solvent penetrated to the rubber surface and caused the swelling in rubber surface and as a result of this action, it has the self-adhesive power. In comparision with the present adhesive a new type of adhesive remarkably improved the maintenance time of adhesion and the durability of this adhesive showed similar aspect. Because it did not exhibit a drop of physical properties of rubber which was caused by swelling effect, we estimate that new type adhesive are very stable and not reacted to several rubber additives. While present adhesive appear the crack at cutting surface of curing rubber that caused by gas, new type adhesive not exist these crack.

• Membrane Journal
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• v.28 no.3
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• pp.187-195
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• 2018

In this work, the morphology of polyvinylidene-co-hexafluoropropylene (PVDF-co-HFP) membranes were systemically investigated using phase inversion technique, to target membrane contactor applications. As the presence of macrovoids degrade the mechanical integrity of the membranes and jeopardize the long-term stability of membrane contactor processes (e.g. wetting), a wide range of dope compositions and casting conditions was studied to eliminate the undesired macrovoids. The type of solvent had significant effect on the membrane morphology, and the observed morphology were correlated to the physical properties of the solvent and solvent-polymer interactions. In addition, to fabricate macrovoid-free structure, the effects of different coagulation temperatures, inclusion of additives, and addition of nonsolvents were investigated. Due to the slow crystallization rate of P(VDF-co-HFP) polymer, it was found that obtaining porous membrane without macrovoids is difficult using only nonsolvent-induced phase separation method (NIPS). However, combined other phase inversion methods such as evaporation-induced phase separation (EIPS) and vapor-induced phase separation (VIPS), the desired membrane morphology can be obtained without any macrovoids.

• Applied Chemistry for Engineering
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• v.17 no.6
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• pp.575-579
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• 2006

Solid electrolyte interface is formed on a carbon electrode used as an anode in Li-ion battery, which can be of $Li^{+}$ intercalation/deintercalation during the first cycle. The passivation film formed by a solvent decomposition during the initial charge process affects cell performance and it was one of the main reason of an initial irreversible capacity. This paper describes the use, for the first time, of $Li_2CO_3$ as the additive for the formation of a passivation film on the carbon surface to suppress the initial irreversible reaction. Chronopotentiometry, cyclic voltammetry, and impedance spectroscopy were used to investigate the effects of the $Li_{2}CO_{3}$ additive. Scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction were also used to monitor changes in the surface morphology and composition of the passivation film formed by solvent decomposition and the precipitation of $Li_{2}CO_{3}$. The addition of $Li_{2}CO_{3}$ to a solution of 1 M $LiPF_{6}$/EC:MA (1:3, v/v) resulted in a decrease in the initial irreversible capacity and it was due to the suppression of the solvent decomposition on the electrode surface.

• Membrane Journal
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• v.20 no.3
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• pp.222-227
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• 2010

The purpose of this study is to prepare forward osmosis (FO) membranes using a variety of cellulose-based polymers and to evaluate the performance of difference depending on each of the polymers and additives. Forward osmosis membranes based on cellulose acetate (CA) and cellulose triacetate (CTA) were prepared through phase inversion. The performance of FO membranes developed, such as flux and salt rejection, was compared under the osmotically- and pressure-driven conditions. In CA FO membranes, the execution time of solvent evaporation and membrane annealing induced the change in membrane performance. But the performance of CTA FO membrane was improved by using additives rather than annealing. Moreover, the flux of CTA FO membrane was $4.46\;L/m^2hr$ but that of CA/CTA FO membrane was $8.89\;L/m^2hr$ in FO mode. The CTA FO membrane with blending CA was more efficient to increase FO permeate flow rather than using a single polymer membrane.

• Clean Technology
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• v.7 no.1
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• pp.13-25
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• 2001

With fast advancement of fine machineries and semiconductor industries in recent decades, the ultra-cleaning of organic chemicals, submicron particles from contaminated unit equipments and products such as silicon wafers becomes one of the most important steps for further advancement of such industries. To date, two kinds of ultra cleaning techniques are used; one is the wet-cleaning and the other is the dry cleaning. In case of wet cleaning, removal of organic contaminants and submicron particles is made by DIW with additives such as $H_2O_2$, $H_2SO_4$, HCl, $NH_4OH$ and HF, etc. While the wet cleaning method is most widely adopted for various occasions, it is inevitable to discharge significant amount of toxic waste waters in environment. Dry cleaning is an alternative method to mitigate environmental pollution of the wet cleaning with maintaining comparable degree of cleaning to the wet cleaning. Although there are various concept of dry cleaning have been devised, the dry cleaning with environmentally-benign solvent such as carbon dioxide proven to show high degree of cleaning from the contaminated porous surface as well as from the bare surface. Thus, special global attention has been placing on this technique since it has important advantages of simple process schemes and no environmentally concern, etc. Thus, this article critically reviews the state-of-the-art of the supercritical fluid drying with emphasis on the thermo-physical characteristics of the supercritical solvent, environmental gains compared to other dry cleaning methods, and the generic aspects of the basic design and processing engineering.

• Journal of the Korean Chemical Society
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• v.42 no.1
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• pp.122-134
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• 1998

In this review, we describe the electrochemical properties of spinel-type lithium manganese oxides $(Li_xMn_2O_4)$ and their failure modes encountered in 4 V lithium rechargable cells. The long-term cyclability (reversibility) of spinel electrodes is determined partly by the purity, size and distribution of spinel particles, and also by the microstructure of electrode plates. A proper selection of electrolytes is another important task in cyclability enhancements. In the spinel preparation, impurity formation and cation mixing should be minimized. The carbon content in composite cathodes should also be minimized to the extent where the cell polarization does not bring about adverse effects on cell performances. The binder content should be optimized on the basis of dispersion of component materials and mechanical strength of the plates. Cathodic capacity losses arising from solvent oxidation and spinel dissolution can be mitigated by using electrolytes composed of carbonates and/or fluorine-containing lithium salts. The carbon additives may be selected after a trade-off between the cell polarization in composite cathodes and the solvent oxidation on carbon surface.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.425-429
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• 1997

Polyisobutenylsuccinic anhydride(PIBSA), an intermediate for the lubricating oil additive, was prepared by the reaction of polyisobutylene(PIB) with maleic anhydride (MA). The functionality, which indicates the extent of reaction of PIB-a and MA, was determined in the various reaction conditions : fuctionality was 0.98 under the reaction conditions of no solvent for 12 hours at $190^{\circ}C$, 0.21 in benzyl alcohol solvent for 12 hours at $190^{\circ}C$, and 0.03~0.20 with various Lewis acids such as $AlCl_3$, $SnCl_4$, $Et_2AlCl$, and $TiCl_4$. The fuctionality also depended on the structure of PIBs. As ${\alpha}$-olefin content (exo-form) in PIB increased, the fuctionality had a higher value. The structure of PIBSA prepared from PIB and MA was determined with FT IR and $^1H$ NMR spectroscopy. Two strong anhydride IR bands at 1782 and $1855cm^{-1}$ were obserbed and two IR bands at 1639 and $897cm^{-1}$ for unsaturated groups of PIB disappeared. The presence of the anhydride was difficult to find by $^1H$ NMR spectroscopy because the anhydride protons gave relatively small peaks over a 2.0~3.0 range. Polyisobutenylsccinimide (PIBSI), a lublicating oil additive, was prepared by the reaction of PIBSA with diaminoethane.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.358-362
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• 2017

In this study, the optimization of extraction parameters (solvent, temperature, time, solvent concentration) for the maximization of polyphenol extraction was performed to produce value-added food and cosmetic additives using a byproduct of coffee extraction process (coffee residue). All of the extraction parameters evaluated in this experiment had significant effects on polyphenol extraction and the results showed the effect of NaOH concentration on the polyphenol production was most significant among tested parameters. Especially, hot water extraction using acid or base was effective rather than hot-water extraction and the addition of 0.1 mol of NaOH increased 1.5 times extraction concentration compared with hot-water extraction using distilled water. It was found that hot-water extraction with NaOH was more effective than hot-water extraction, and 36.5 mg GAE/g DM was obtained under optimum condition of $100^{\circ}C$, 2 mol of NaOH and 30 min. This result was 2.9 times higher than that of 12.5 mg GAE/g DM obtained from the hot-water extraction before optimization. Thus, coffee residue could be used for food and cosmetic industry as a high-value additive such as antioxidant.

• Journal of the Korean Society of Food Culture
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• v.20 no.6
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• pp.703-708
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• 2005

This study was carried out to compare the antioxidant activities of the ether, butanol, water extracts from chestnut inner shell(Castanea crenata Sieb. et Zucc.) with those of tocopherol and BHA in soybean oil. All additives were added to soybean oil on the quantities of 0.02%. Comparing the antioxidant activities under autooxidation condition at $45.0{\pm}0.5$ for 42days of the extracts were recorded in the order of butanol>ether>control>BHA>tocopherol depending on the solvent. Under the condition at $60.0{\pm}0.5^{\circ}C$ for 32days, the butanol extracts represented the high antioxidation effect, however, there was no significant differences between the ether extracts and control. Under thermal oxidation condition, the ether extract showed stronger antioxidant activity than those of the butanol extract. In the results of polyphenol compound analysis, ellagic acid, quercetin, morin, naringenin, flavanol were included in the ether extracts and ellagic acid, naringenin, gallic acid, flavanol were included in the butanol extracts, respectively. Among them, ellagic acid in ether extract and gallic acid and naringenin in butanol extracts seed to increase the antioxidant activities in the substrate oil.

• Food Science and Preservation
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• v.13 no.6
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• pp.762-768
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• 2006

To assess utilization of onions extract as natural food additives, ethyl acetate, ethanol and hot water extract of freeze dried onions (red, white and yellow) were exmined for their chemical component and nitrite scavenging activity. Contents of total organic acid and total free sugar were in the range of $135.4{\sim}1,2557mg%$ and $51.7{\sim}62.9%$ as dry matter bases, respectively, and then their content of three onions were higher in ethylacetate and hor water extracts than in ethanol extract. Contents of total phenol and total flavonoids were in the range of $9.3{\sim}$13.3 % and $159.8{\sim}584.1mg%$ as dry matter bases, respectively, and their content of red onion extract by three solvent were higher than those of other onion extract. Nitrite-scavenging activities (NSA) of onion extracts were increased by lowering pH and elevating onion concentrations, and their values of ethanol and hot water were about 55% in addition of 10 mg/mL of red onion extract showing that NSA of red onion was twice higher than that of the other onions. In conclusion, the result indicated that red onion extract was very effective to inhibit nitrosamine formation at low pH condition as natural nitrite scavenging agent.