• Carbon letters
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• v.10 no.3
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• pp.190-197
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• 2009

Various silanes, amino silane, vinyl silane, sulfur silane (TESPD), and ZS (TESPD/zinc soap complex), are added into chlorinated isobutylene-isoprene copolymer (CIIR)/soft clay/carbon black (CB) and CIIR/hard clay/CB compounds and they are investigated with respect to the vulcanization characteristics, the processability, and the mechanical properties. Comparing hard clay and soft clay filled compounds, hard clay (Suprex) filled system shows a higher die C tear than the soft clay (GK) filled one. The other properties (Mooney, extrusion torque/pressure, torque rise ($M_H-M_L$), modulus at 300%) are close to each other. Among various silanes, the ZS treated hard clay (Suprex) compound shows the highest mechanical property following hard clay(S)/vinyl silane(V) and soft clay(GK)/vinyl silane(V) compounds. The TESPD and the ZS effectively helps a formation of a strong 3-dimensional network structure between silica and CIIR via coupling reaction due to bifunctional nature of TESPD. In addition to that, the ZS added compounds show both a better processability and mechanical properties compared to the S2 ones at low concentration due to improved compatibility between zinc soap and CIIR matrix. Only the ZS added compound shows both improved processabilities (Mooney, Extrusion torque-& pressure) and improved mechanical properties (degree of crosslinking, elongation modulus, tear, and fatigue to failure counts) on both CIIR/hard clay/CB and CIIR/soft clay/CB compounds.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.201-205
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• 1999

Hydroxypropylmethylcelluloses (HPMC) are cellulose ethers which may be used as the basis for hydrophilic matrices for controlled release oral delivery and offer the advantages of being non-toxic and relatively inexpensive. In this work, we designed new drug release system using HPMC as matrix, manufactured by direct compression technology and have investigated the effects of the controlling factors on drug release from a swellable hydrophillic delivery system. It was found that the release rate of the drug decreased with increasing the polymer molecular weight and the polymer content in tablets, and was independent of compaction pressure and pH of dissolution fluids. Especially, the ability of the anionic surfactant, sodium laurylsulfate, to retard the release of pseudoephedrine hydrochloride from HPMC was characterised. With increasing the concentration of the sodium laurylsulfate within the matrix, drug release rate decreased. It is believed that, provided the pseudoephedrine hydrochloride and the sodium laurylsulfate are oppositely charged, they will bind together in situ within the HPMC matrix, leading to reduced drug release rates.

• Journal of Pharmaceutical Investigation
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• v.38 no.4
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• pp.241-247
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• 2008

Paclitaxel is a taxane diterpene amide, which was first extracted from the stem bark of the western yew, Taxus brevifolia. This natural product has proven to be useful in the treatment of a variety of human neoplastic disorders, including ovarian cancer, breast and lung cancer. Paclitaxel is a highly hydrophobic drug that is poorly soluble in water. It is mainly given by intravenous administration. Therefore, The pharmaceutical formulation of paclitaxel ($Taxol^{(R)}$; Bristol-Myers Squibb) contains 50% $Cremophor^{(R)}$ EL and 50% dehydrated ethanol. However the ethanol/Cremophor EL vehicle required to solubilize paclitaxel in $Taxol^{(R)}$ has a pharmacological and pharmaceutical problems. To overcome these problems, new formulations for paclitaxel that do not require solubilization by $Cremophor^{(R)}$ EL are currently being developed. Therefore this study utilized a supercritical fluid antisolvent (SAS) process for cremophor-free formulation. To select hydrophilic polymers that require solubilization for paclitaxel, we evaluated polymers and the ratio of paclitaxel/polymers. HP-${\beta}$-CD was used as a hydrophilic polymer in the preparation of the paclitaxel solid dispersion. Although solubility of paclitaxel by polymers was increased, physical stability of solution after paclitaxel/polymer powder soluble in saline was unstable. To overcome this problem, we investigated the use of surfactants. At 1/20/40 of paclitaxel/hydrophilic polymer/ surfactant weight ratio, about 10 mg/mL of paclitaxel can be solubilized in this system. Compared with the solubility of paclitaxel in water ($1\;{\mu}g/mL$), the paclitaxel solid dispersion prepared by SAS process increased the solubility of paclitaxel by near 10,000 folds. The physicochemical properties was also evaluated. The particle size distribution, melting point and amophorization and shape of the powder particles were fully characterized by particle size distribution analyzer, DSC, SEM and XRD. In summary, through the SAS process, uniform nano-scale paclitaxel solid dispersion powders were obtained with excellent results compared with $Taxol^{(R)}$ for the physicochemical properties, solubility and pharmacokinetic behavior.

• The Korean Journal of Pesticide Science
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• v.8 no.2
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• pp.88-94
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• 2004

In order to evaluate NMR spectrometer as the analytical tool for identification of individual adjuvant in crop protection products, the standard sample of individual adjuvant was analyzed by NMR spectrometer and then the formulation of crop protection products was also analyzed. Almost polymer system of surfactant was a co-polymer and there was an excess of ethylene. The most intense signal comes from long polyethylene blocks, 70.5 ppm. The carbonyl groups of ester group resonate at 173.5 ppm. Analytical sample was prepared in NMR tube without extraction, cleanup, concentration, or chromatographic separation. Identification of individual adjuvant in crop protection products was conducted by comparison of sample and reference spectra. NMR spectrometer was useful to analyze adjuvant in crop protection products without preparation process.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.3
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• pp.285-293
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• 2018

A structure of coacervate affects the adsorption of oil and polymer as a conditioning ingredient. This study aims to elucidate a structural characterization of the coacervate of which is a mixture of alkyl cellulose and guar gum. It is well known that the guar gum supports stiffness to the hair when it is adsorbed on the hair. However, addition of guar gum in the formulation composed of alkyl cellulose tremendously increased flexibility in hair. The stable complex system is induced by an electrostatic force between a head group of anionic surfactant and an quarternary ammonium at the alkyl cellulose, and the affinity of alkyl chain to the oil inside the micelle of surfactant by hydrophobic interactions. Taken together, amount of the coacervate increased oil-delivery upon hair in shampooing and these caused a low bending rigidity and calming on the hair swatch.

• Polymer(Korea)
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• v.36 no.2
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• pp.202-207
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• 2012

Biodegradable poly(${\varepsilon}$-caprolactone)(PCL) microcapsules containing pseudomonas were prepared by W/O/W emulsion system. The characteristics and release behaviors of the microcapsules were investigated as a function of manufacturing conditions. The morphology and particle distribution of the microcapsules were observed by a scanning electron microscope and a particle size analyzer. The release behaviors of the pseudomonas were determined using a cell culture method. It was found that smooth and spherical microcapsules were formed by W/O/W emulsion system and particle size was in the range of 10 to 60 ${\mu}m$. The release behaviors of the pseudomonas were influenced by the manufacturing conditions. It was indicated that the increase of the surfactant content and stirring rate led to an increased release rate, resulting from the high specific surface area of the smaller particle size, and the increase of the PCL content provided the sustained release behaviors by the delay effect of diffusion in the release medium.

• Clean Technology
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• v.12 no.3
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• pp.145-150
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• 2006

Electrolysis of aqueous solution produces hydroxide ions and proton ions for the hydrolysis of reactive organic compounds, and oxidizing agent such as hypochlorite ions for the oxidative decomposition of organic chemicals. Electrolytic decomposition of dying chemicals was tested with our custom made system, and analyzed by HPLC and UV-VIS spectrophotometer. The electrolytic system could decompose dying chemicals with very high reactivity and low cost. Disposal of byproduct and refill of reactant during electrolysis was not necessary. Decomposition time of dying chemicals is compared under similar conditions, and application to water purification is discussed.

• KSBB Journal
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• v.26 no.4
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• pp.283-292
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• 2011

Solid dispersion is one of well-established pharmaceutical techniques to improve the dissolution and consequent bioavailability of poorly water soluble drugs. It is defined as a dispersion of drug in an inert carrier matrix. Solid dispersions can be classified into three generations according to the carrier used in the system. First and second generations consist of crystalline and amorphous substances, respectively. Third generation carriers are surfactant, mixture of polymer and surfactants, and mixture of polymers. Solid dispersions can be generallyprepared by melting method and solvent method. While melting method requires high temperature to melt carrier and dissolve drug, solvent method utilizes solvent to dissolve the components. The improvement in dissolution through solid dispersions is attributed to reduction in drug particle size, improvement in wettability, and/or formation of amorphous state. The primary characteristics of solid dispersions, the presenceof drug in amorphous state, could be determined by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and fourier-transformed infrared spectroscopy (FTIR). In spite of the significant improvement in dissolution by solid dispersion technique, some drawbacks have limited the commercial application of solid dispersions. Thus, further studies should be conducted in a direction to improve the congeniality to commercialization.

• Journal of the Korean Applied Science and Technology
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• v.22 no.2
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• pp.96-105
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• 2005

Core-shell polymers of methyl methacrylate-styrene system were prepared by sequential emulsion polymerization in the presence of sodium dodecyl benzene sulfonate(SDBS) as an emulsifier using ammonium persulfate(APS) in an initiator and the characteristics of these core-shell polymers were evaluated. Core-shell composite latex has the both properties of core and shell components in a particle, whereas polymer blends or copolymers show a combined physical properties of two homopolymers. This unique behavior of core-shell composite latex can be used in various industrial fields. However, in preparation of core-shell composite latex, several unexpected matters are observed, for examples, particle coagulation, low degree of polymerization, and formation of new particles during shell polymerization. To solve this matters, we study the effects of surfactant concentrations, initiator concentrations, and reaction temperature on the core-shell structure of PMMA-PSt and PSt-PMMA. Particle size and particles distribution were measured by using particle size analyzer, and the morphology of the core-shell composite latex was observed by using transmission electron microscope. Glass temperature was also measured by using differential scanning calorimeter. To identify the core-shell structure, pH of the composite latex solutions was measured.

• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.694-701
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• 2015

In order to get stabilized pure retinol in skin care cosmetics, developing the three layered matrix bead capsules were studied. This study relates to make a cosmetic composition using the three layered matrix capsule that could increase the stability of the active ingredient. A primary encapsulation, vitamin A (pure retinol) of active ingredient was perfectly capsulated into water-in-oil (Water-in-Oil: W/O) emulsion vesicle using PEG-10 dimethicone copolyol emulsifier. A secondary encapsulation of multiple emulsion of the water-in-oil-in-water (W/O/W) emulsion blending W/O emulsion using sucrose distearate of surfactant was developed using homogenizing emulsifying system. Pure retinol of active ingredient was stably capsulized to inside the W/O/W-multiple emulsion in order to load the triple matrix capsulation. By coating it with a polymer matrix base, encapsulated in the triple layered type, which were developed bead encapsulation of 2~10mm uniformly size. To show beautifully appearance capsulated bead type, these finish particles in this triple matrix layer were developed as a gold, green, dark brown, silver and blue color were encapsulated in the bead types. Structural particle certification of triple matrix layer was observed through SEM analysis. Stability of pure retinol was remained stable more than 99.7% for 30 days at $42^{\circ}C$ incubating conditions compared with non-capsule. This technology was applied in different formulations such as various sizes and colors that by applying the skin care cosmetics. In the future, this technology to encapsulate an unstable active ingredient, we expect to be expanded this application in the food and drug as a time delivery system.