• Textile Coloration and Finishing
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• v.13 no.1
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• pp.38-44
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• 2001

The adsorption ability of dyes on chitin, a natural polymer was investigated for decolorization of dye wastewater. Chitin was manufactured in lab by decalcification in dilute aqueous hydrochloric acid solution and deproteination in dilute aqueous sodium hydroxide solution with shrimp shells. Absorbance of residue solution of dyebaths after dye adsorptions of chtin were measured in varieties of dye concentration and dipping periods. Three kinds of Direct dyes -C.I. Direct Red 81 (red 81), C.I. Direct Brown l(brown 1) and C.I. Direct Green 26(green 26) - were used. Red 81 and brown 1 have smaller molecular weight than green 26. The results from experimentals were of]tamed as follows: 1) Adsorption of green 26 was improved in dyebath by addition of salt, but red 81 and brown 1 were not found any improvements. 2) Smaller size of chitin particles could be absorbed much more speedy. In this experiments, the smallest range of chitin particle size was $250\mu{m}$ and less. 3) The most efficient amount of chitin for 20m1 of dyebath was 0.2g, 4) Both of red 81 and brown 1 showed good and speedy adsorption abilities as dyestuffs of over 90 percent in just one minute in dyebath of 0.01% dye concentration. But green 26 was absorbed slowly because of its large molecular weight. It took 40minutes to absorb dyestuffs of over 90 percent in dyebath of 0.01% dye concentration.

• Macromolecular Research
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• v.12 no.5
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• pp.534-539
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• 2004

Two biopolymers, silk fibroin (SF) and chitosan, were conjugated by tyrosinase (EC 1.14.18.1), a polyphenolic oxidase, to improve their physicochemical properties, such as their thermal properties and morphological stabilities in organic solvents. The crosslinking between SF and chitosan took place mainly through Michael addition reactions. A main reaction between the amino groups in chitosan and o-quinone, the oxidation product of the tyrosyl residue in SF, was confirmed by UV spectroscopy. Measurements of viscosity and light scattering indicated that the crosslinked SF/chitosan conjugate was compact: it had a smaller particle size because of tight bonding forces between the SF and chitosan molecular chains. Thermal decomposition of SF/chitosan conjugates crosslinked by tyrosinase occurred at higher temperatures. The adhesiveness of the SF/chitosan conjugates decreased steadily as the crosslinking reaction progressed. We propose that this new crosslinking method be used for the preparation of silk fibroin/chitosan conjugates using tyrosinase. We expect that SF/chitosan conjugates crosslinked by tyrosinase can be used preferentially in biomedical applications because of its unique properties and non-toxicity.

• Journal of the Korean Chemical Society
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• v.57 no.5
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• pp.625-633
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• 2013

A type of polycyclotriphosphazene derivative (PCTPD), hexasulfanilic acid polycyclotriphosphazene (HSACP) and HSACP grafting SPEEK, sulfonated poly[2-(petachloropolycyclotriphosphazene-oxy)] etheretherketone (SPPSACPEEK) were synthesized, which were characterized by FTIR and $^{31}P$ NMR. Then three types of composite membranes such as HSACP grafting SPEEK, HSACP blending SPEEK, and nano $Y_2O_3$ doping and HSACP grafting SPEEK, respectively, were continuously prepared by solution-casting method. Comparing to SPEEK membranes with different amount of HSACP grafted or blended, grafting 15 wt% HSACP and doping 10 wt% nano $Y_2O_3$ SPEEK membrane conducted outstanding overall behavior of proton conductivity reaching $3.18 {\times}10^{-2}$ S/cm at $90^{\circ}C$ which was merely junior to SPEEK with 15 wt% HSACP grafted, methanol permeability coefficient getting $9.46{\times}10^{-8}cm^2{\cdot}s^{-1}$, swelling degree of 20.9% and solid residue of 98.98% which was superior to all specimen.

• Elastomers and Composites
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• v.55 no.4
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• pp.300-305
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• 2020

In recent times, polymeric foams have been popularly used in various applications. To meet the demand for these applications, polymer foams with excellent mechanical and thermal properties are required. In particular, silicone foam has gained significant attention owing to its superior thermal properties and low density. In this study, the mechanical and thermal properties of silicone foams filled with wollastonite were investigated. A maximum tensile strength of 98.3 kPa was obtained by adding 15 phr of wollastonite. The specific gravity did not exhibit a marked difference up to 10 phr, but it increased substantially above 15 phr wollastonite. Thermogravimetric analysis indicated that adding wollastonite to the silicone foam increased both the amount of residue and the thermal decomposition temperature. The morphologies of the silicone foams filled with wollastonite were observed by scanning electron microscopy.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.524-536
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• 1994

Chitosan is known to be a good biocompatible natural polymer. Polyethyleneglycol monomethacrylates(PEGM) were grafted onto chitosan and their reaction conditions and properties of the graft polymers obtained were estimated. Using ceric ammonium nitrate(CAN) as the initiator, the optimum condition for graft polymerization was determined amount of the initiator and monomer concentrations and reaction time. Grafting yields such as total conversion, the percentage of grafting and the efficiency of grafting were calculated and examined the optimum reaction condition for high grafting yields. The percentage of grafting and total conversion were maximum at condition that the concentration of initiator was $4{\sim}5{\times}10^{-3}M$, the concentration of monomer was 0.5~0.6M, the reaction time was 2~3 hours and the reaction temperature was about $40^{\circ}C$. Thermal characteristics, solubility for chitosan solvents and inherent viscosity of synthesized graft copolymers were investigated. In high initiator concentration, characteristics of chitosan were greatly diminshed. In case of inherent viscosities, chitosan-g-PE-90 was 2.81 dl/g, chitosan-g-PE-200, 3.01dl/g and chitosan-g-PE-350, 4.93dl/g. And a tendency of viscosity increase depending on the length of ethylene oxide residue was confirmed. Degree of swelling, tensile strength, elongation of membrane prepared from graft copolymers were determined. Properties of graft copolymers were affected by percentage of grafting and length of ethylene oxides residue in polyethylene glycol monomethacrylates. Tensile strength, elongation and degree of swelling of graft copolymers were remarkably improved than chitosan. As percentage of grafting increased, the amount of drug permeation was also increased.

• Resources Recycling
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• v.22 no.2
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• pp.71-77
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• 2013

Electronic products such as appliances, computers, and cellular phones have printed circuit boards (PCBs) in common and the PCBs in the waste electronic products contain valuable metals and organic resins. In Korea, recovery and recycling of the organic resins as well as the valuable metallics from the wastes are required indeed as the most of resources are being imported from abroad. In this article, the patents and papers for the recycling of organic residues from the waste PCBs were collected and analyzed. The open patents of USA (US), European Union (EP), Japan (JP), and Korea (KR) and SCI journals from 1979 to 2012 were investigated. The patents and journals were collected using key-words and filtered by the definition of the technology. The patents and journals were analyzed by the years, countries, companies, and technologies and the technical trends were discussed in this paper. It is showed sluggish relatively activity of published papers and patent applications for polymer manufacturing technology in local and abroad.

• Korean Journal of Environmental Biology
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• v.20 no.4
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• pp.316-324
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• 2002

To investigate the mutational spectrum of laccase (Lac) genes (lac -A and lac -B) involved in degrading lignin which is the recalcitrant cell wall polymer, the genes of the Pleurotus ostreatus mutants induced by gamma ray radiation were amplified by PCR and were cloned. All partial lac-A genes of 4 mutants (PO-6, -7, -14 and -15) consisted of 1763 base pairs due to the deletion of two bases (491-nt and 492-nt) and addition of one base (875-nt) in 1764 base pairs of lac -A gene of PO-1. Totally 36 mutational hot spots were detected and 32 positions were mutated in all of those 4 mutants simultaneously. These mutations were predominantly A : T -> G : C transitions (40%). Putative amino acid sequences of lac -A genes of mutants have one simultaneous mutated residue (from Thr-44 to Ala-44). The 1764 bp of partial lac -B gene was cloned only in PO -5 mutant and contained 19 mutated bases. These mutations were predominantly G : C->A : T transitions (45%). Lac-B protein of PO-5 has two mutated residues of Glu-290 and His-363 from Ala-290 and Phe-363, respectively. The hyper-mutational positions were concentrated in specific regions of between 50-nt and 900-nt in lac genes. These results suggested that the mutational hotspots responded to gamma radiation could be in some genes, at least lac -A and lac -B of p. ostreatus.

• Resources Recycling
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• v.18 no.6
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• pp.38-45
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• 2009

Dissolution characteristics of magnesite ore in hydrochloric acid solution and removal of impurity were investigated. The dissolution yield increased with increasing temperature and with decreasing particle size. The optimum conditions for dissolution were found to be reaction period of 120 min, reaction temperature of $80^{\circ}C$ and mean particle size of 100. Under optimal dissolution condition the extraction of Mg was 98%. It was found that most of Si and Al exist in the residue, and they can be removed by filtering. Dissolved impurity ions were precipitated as metal hydroxides by pH adjustment. Polymers were used as coagulants for metal hydroxides and the suitable coagulant dosage was 1mg/100ml of non-ionic polymer.

• Membrane Journal
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• v.29 no.3
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• pp.183-189
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• 2019

Amphiphilic PCZ-r-PEG random copolymer assisted solvothermal process is used to prepare mesoporous $TiO_2$ microspheres generated from nanoparticles by self-assembly method. Synthesized PCZ-r-PEG is characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC) and transmission electron microscopy (TEM). The mesoporous $TiO_2$ are prepared by PCZ-r-PEG, glucose, water in tertrahydrofuran solution at $150^{\circ}C$ for 12 h and the $TiO_2$ microspheres are calcined at $550^{\circ}C$ for 30 min to further crystallize and organic residue are removed. Morphology and crystallization phase is characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. The mesoporous $TiO_2$ crystallized in pure anatase phase with diameter of $300{\pm}20nm$.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1043-1046
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• 1998

Aluminium based inorganic flocculants are extensively used in this country in the removal of fine particles present in the raw water for the production of drinking water. These inorganic flocculants, however, have potential hazard of high residual aluminium ions in the treated waters, which is known to be one of the reasons of alzheimer's disease. Inorganic flocculants alone are sometimes incapable of treating water when there are excessive turbidity in the raw water sources due to flooding. A polyamine type polymeric flocculant has long been used to treat raw water in the drinking water production in the European countries and United State of America. The optimum reaction conditions such as mole ratio of epichlorohydrin(EPI) to dimethylamine(DMA), reaction temperature and time for each stage for the pilot scale preparation of polyamine from EPI-DMA was studied in this work. The variation of intrinsic viscosity and flocculating efficiency in the water treatment of the synthesized polyamines were evaluated. The residual materials after polymerization reaction were analyzed by gas chromatography to study the effect of variation of reaction conditions.