• Journal of Food Hygiene and Safety
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• v.13 no.1
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• pp.34-40
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• 1998

Chitin is known as biodegradable natural polymer. But, in spite of various application of chitin from waste marine sources, commercial use of chitin has been limited due to highly resistance to chemicals and the absense of proper solvents. Therefore, we studied that another viscosity chitosan were prepared from chitin which were deacetylated under various concentration of NaOH solution, reaction time and temperature by the application of Mirna's method. The major parameters for these manufacturing methods were found to be concentration of alkali solution, reaction time and temperature etc. Besides, we studied that various chitosan derivatives were prepared from chitin by crosslinkage with epichlorohydrin and 1,3-dichloropropanol. The effects of these parameters on another viscosity(molecular weight) chitosan and crosslinked chitosan dervatives were investigated by various analysis apparatus. SEM analysis showed that both chitin and chitosan had a particle shaped morphology and another molecular weight chitosan according to the particle size was much smaller than that of chitin.

• Polymer(Korea)
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• v.25 no.1
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• pp.63-70
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• 2001

The objective of this study was to investigate the effect of cure type on the processing and physical properties under conditions of similar stress-strain properties. On the carbon black filled natural rubber(NR) based compound, the induction time decreased, but the cure rate became fast with increasing loading of sulfur donor agent. Tensile strength was little affected on the curing type. However, elongation generally decreased with increasing accelerator. Effect of cure type on the blow-out properties was followings: CV

• Membrane Journal
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• v.15 no.4
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• pp.281-288
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• 2005

The hyaluronic acid (HA) with excellent biocompatibility can be combined with lactide, the ester dimer of polylactide, with good biodegradability to produce biocompatible materials applicable to drug delivery system. By freeze drying method, HA and lactide were crosslinked with crosslinking agent, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide. Degree of lactide and EDC reaction was determined by the analysis of nuclear magnetic resonance (NMR) spectroscopy. The degree of lactide and EDC reaction increased and swelling ratio decreased as the mole ratio of lactide to HA or crosslinking agent concentration increased or reaction temperature decreased. The drug release experiment result from membranes having different degree of lactide reaction showed that drug release rate reduced in proportion to the degree of lactide reaction. The drug release experiment result from drugs having different hyrodphobicity showed that the more hydrophobic drug was released more slowly.

• Polymer(Korea)
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• v.29 no.1
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• pp.1-7
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• 2005

Interpenetrating polymer network (PN) is a mixture of network polymers. The characteristics of IPN material is the control of morphology during the IPN synthesis. By controlling the relative kinetics of chemical reaction (as well as gellation) and phase separation, the morphology of IPN can be controlled to obtain materials with nano-scale domain and also the co-continuous phase. Other important advantage is the fact that the morphology is permanent due to the presence of the physical interlocking between the networks. The combination of hydrophilic polyurethane and hydrophobic polystyrene in IPN form provides enhanced blood compatibility due to the co-existence of the hydrophilic and hydrophobic domains in nano-scale on the surface. The reaction temperature, reaction pressure and the degree of crosslinking were varied during the IPN synthesis and the morphology and blood compatibility of the resulting IPN materials were studied.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.112-117
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• 2021

In this study, a method of self-assembly of peptides based on irreversible covalent bonds was studied by mimicking a biological covalent bond, dityrosine bond. A tyrosine-rich short peptide monomer having the sequence of Tyr-Tyr-Leu-Tyr-Tyr (YYLYY) was selected to achieve a high-density of dityrosine bond. The peptide nanoparticles covalently self-assembled with dityrosine bonds were synthesized by one-step photo-crosslinking of a peptide using a ruthenium catalyst under visible light. The effect of the concentration of each component for the size of the peptide nanoparticle was studied using dynamic light scattering, UV-Vis spectroscopy, and transmission electron microscopy. As a result, the synthesis conditions for size of the peptide nanoparticles ranging from 130 nm to 350 nm were optimized.

• Magazine of the Korea Concrete Institute
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• v.14 no.6
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• pp.49-54
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• 2002

아직까지 우리나라에서 폴리머 시멘트 콘크리트가 콘크리트와 같이 광범위하게 사용되고 있는 것은 아니지만 건설재료로서의 사용이 증가하는 추세에 있다. 폴리머 콘크리트의 제조에는 결합재로서 물이나 시멘트가 전혀 사용되지 않고 수지(resin)만을 사용한다. 각종 수지가운데 많이 이용되고 있는 것은 에폭시 수지, 불포화 폴리에스테르 수지, 우레탄 수지, 퓨란 수지 등이 있다. 그러나 원료사정이 국가마다 다르기 때문에 폴리머 콘크리트의 결합재로 사용되는 액상수지 역시 차이가 있다. 우리나라의 경우는 에폭시수지, 불포화 폴리에스테르 수지 및 우레탄 수지가 주로 사용되고 있으며, 가까운 일본의 경우는 폴리머 콘크리트의 결합재로서 워커 빌리티, 저온경화성, 내후성 등이 우수한 메타크릴산 메틸도 사용되고 있다. 또한 폴리머 모르타르 및 콘크리트의 경화반응에 방해를 주지 않도록 충전재 및 골재 등은 건조시켜 함수율이 0.5 % 이하가 되도록 사용하고 있으나, 지금은 흡수제, 가교제 등의 혼화재료가 개발되어 함수율을 3% 까지 허용하고 있으며, 지금까지 불가능하게 생각되었던 폴리머 콘크리트에 대한 레디믹스트 콘크리트(레미콘) 개발도 흥미를 끌고 있다.(중략)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.2
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• pp.134-143
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• 2005

Collagen is the important structural proteins in mammals with various peptide composition and cross-linkings. The direct analysis of collagen protein was not suitable because of its structural complexity and diversity. In this study, we suggest the simple way of collagen analysis by introducing matrix-assisted laser desorption/ionization time-of flight mass spectrometry (MALDI-TOF MS) to identify the collagen and its trypsin-digested fragments, and by subsequent time-of-flight tandem mass spectrometry(Q-TOF MS/MS) to analyze the amino acid sequences of identified fragments. Using the collagen samples extracted from the tail of mouse, 10 separated bands were found in SDS-PAGE, and the masses of most bands could be more finely determined by MALDI-TOF MS. When each 10 separated proteins was tryptic digested and introduced to MALDI-TOF, the Gly1056-Arg1073 fragment from $\alpha_1$-chain was identified in four bands, and the Gly1056-Arg1073 fragment from $\alpha_2$-chain was identified in five bands, both in type I collagen. Although few fragments were found because of the cross-linkings left in digested collagen sample, it could be determined that the type I collagen existed at least in 7 separated bands. When the amino acid sequences of two identified fragments were analyzed by Q-TOF MS/MS, both sequences were identical with those determined by MALDI-TOF MS. It suggested that the two peaks in MALDI-TOF MS caused by the fragments identified in this work could be used as the fingerprint to simply identify type I collagen in protein samples.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.4039-4045
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• 2014

The crystallization behavior of irradiated polypropylene (PP) and the blend is an important parameter for polymer processing. Blends of PP/low density polyethylene (LDPE) with different LDPE contents were prepared by melt mixing in a twin screw extruder. The effect of the LDPE content on the irradiation effectiveness of the PP/LDPE blend with trimethylolpropane-trimetacrylate (TMPTMA) as a crosslinking co-agent was investigated in conjunction with the LDPE loading in the blend. The non-isothermal crystallization and crystal structure were measured by DSC, X-ray diffraction (XRD), and polarized optical microscopy (POM). A decrease in the melting temperature of PP was observed due to irradiation, which may be due to the PP chain scissioning effect of irradiation. The Ozawa component n represents a rod shaped, disc shaped and sphere-shaped geometry of the crystal if the value corresponds to 2, 3 and 4, respectively. Based on Ozawa analysis, the values of n were 3.8 and 2.3 for the pure PP and PP blends with 30 wt% LDPE, respectively. The fact that the crystal geometry of PP changed from spherical to disc and rod shaped was confirmed by Ozawa analysis and POM. The ${\beta}$ form XRD peak of the PP/LDPE blend at $16.1^{\circ}$ disappeared after irradiation due to the crosslinking reaction.

• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.749-754
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• 2010

In this study, rubber vulcanization property, change in physical property, morphology and chemical characteristics of blended rubber depending on various IR/CR ratio were investigated for the purpose of the improvement of material property and durability. The effect of surface treatment by chlorine on the friction coefficient was also studied with various conditions of surface treatment. In terms of vulcanization property, as the amount of CR content increased, the speed of cure was decreased, while the density of crosslinking stayed constant. It means hardness and modulus were increased as the CR content increased. It is related to change in cure property and mechanical strength was improved by the effect of crystallization reaction. In the aging property, as the CR content increases, the changed amount of basic properties were decreased, which acts as a reducing factor in change of aged property by complementing weak point in mechanical property. It was found that the degree of property change for surface treated samples were reduced. According to the microscopic result, the degree of surface dispersion on rubber blends was increased by increasing CR content. Rubber surface showed uniform direction in pattern with increased smoothness and luster by treatment with chlorine. The degree of rubber reforming was measured by the remaining amount of chlorine and the friction coefficient was dependent on the amount of chlorine combined with rubber. In the initial stage of surface treatment, from 10 to 40 phr, the friction coefficient of specimen was rapidly reduced. However, as the concentration of chlorine solution increased, the change in friction coefficient was decreased.

• Elastomers and Composites
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• v.14 no.3
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• pp.161-168
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• 1979

이 논문(論文)의 목적(目的)은 열적안정성(熱的安定性) 및 내노화성면(耐老化性面)에 있어서 디엔제3성분단위체(第三成分單位體)(diene termonomer)의 각각(各各)의 종류(種類)가 EPDM의 중합체(重合體)의 성질(性質)에 미치는 효과(效果)를 구명(究明)하는데 있다. 제3성분단위체(第三成分單位體) 5종(種)으로 각각(各各) 다음과 같다. 즉, ethylidene norbonene(ENB), butadiene(BD), dicyclopentadiene(DCPD), methyltetrahydroindene (MTHI) 및 1,4-hexadiene(HD)이다. 이들을 써서 만든 각각(各各)의 EPDM은 동(同)몰의 불포화도(不飽和度)로 만들어졌다. 또한 가황계(加黃系)는 동일(同一)한 황/촉진제계(黃/促進劑系)를 사용(使用)하였다. ENB-EPDM이 순(純)고무배합체(配合體) 및 충전제함유배합체(充塡劑含有配合體)의 가황(加黃)에 있어서 모두 함께 가장 빠른 가황속도(加黃速度)를 보였다. HD-EPDM은 순(純)고무배합체(配合體)에서 가황속도(加黃速度)가 가장느렸으나 충전제함유배합물(充塡劑含有配合物)에서는 DCPD-EPDM보다는 발랐다. BD-EPDM을 제외(除外)한 이들 중합체(重合禮)는 거의 같은 초기가교밀도(初期架橋密度)를 갖는다. 가교밀도(架橋密度) 및 가교형(架橋型)을 분석(分析)하여 보면 BD-EPDM 쇄(鎖)에서 부타디엔 단위(單位)는 블럭을 이루고 있다. 또한 HD-EPDM은 순(純)고무가황체(加黃體) 및 충전제배합가황체(充塡劑配合加黃體)에 있어서 원가교결합(原架橋結合)의 50%가 monosulfide의 구조(構造)를 가지고있다. 이외(外)의 4종(四種)의 EPDM 폴리머는 보다 낮은 monosulfide구조를 가진다. $177^{\circ}C(350^{\circ}F)$의 노화온도(老化溫度)에서 ENB 및 HD폴리머는 약(約) 65% monosulfide 가교(架橋) 및 거의 동일(同一)한 파괴에너지값$(E_b)$을 가진다. 그러나 1,4HD의 원가교(原架橋)의 monosulfide 구조함량(含量)이 보다 높다고 해서 그의 내노화성(耐老化性)이 다른 폴리머보다 더 좋다고는 생각되지 않는다. DCPD는 $177^{\circ}C(350^{\circ}F)$의 노화온도(老化溫度)에서 똑같은 monosulfide가교(架橋)를 가지나 노화온도(老化溫度)가 $259^{\circ}C(500^{\circ}F)$로 높아짐에 따라 monosulfide 함량(含量)도 증가(增加)한다. $550^{\circ}F(287.7^{\circ}C)$의 노화온도(老化溫度)에서는 EPDM폴리머의 모든 가교(架橋)가 monosulfide구조가 되나 전가교밀도(全架橋密度) 및 $E_b$ (신장률(伸長率), 절단시(切斷時)의)는 대단(大端)히 낮은 것으로 나타나는데 이것은 산화(酸化)에 의한 노화(劣化)에 기인(基因)되는 것으로 보인다. 질소기류(窒素氣流)속에서의 TGA의 분석결과(分析結果)를 보면 EPDM 가황체(加黃體)는 $800\sim935^{\circ}F(427\sim502^{\circ}C)$의 온도범위(溫度範圍)에서 분해(分解)되며 공기중(空氣中)에서는 $750\sim935^{\circ}F$ 범위(範圍)에서 분해(分解)한다.