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폴리아미드계 수지를 이용한 핫멜트 접착제의 기능 향상 - (Ⅰ) 접착제의 물성 -
전영식,홍영근,정경호 ( Young Sik Chun,Young Keun Hong,Kyung Ho Chung ) 한국공업화학회 1996 공업화학 Vol.7 No.1
기존의 ethylene-vinyl acetate 핫멜트 접착제는 시간에 따른 크리프 특성과 내열성 등의 한계로 사용에 제한이 있으므로 물성의 향상을 위해 폴리아미드계 수지를 이용한 새로운 핫멜트 접착제 개발에 관하여 연구하였다. 폴리아미드 단일중합체의 경우 융점과 용융점도가 매우 높기 때문에 대신 나일론6, 나일론66, 나일론12로 이루어진 삼원공중합체 혹은 블렌딩 수지를 사용하므로써 분자쇄의 규칙성 파괴로 인해 용융점도와 용융점을 강하시킬 수 있었다. 이로써 선택된 수지가 핫멜트 접착제의 베이스 수지로 적절함을 알 수 있었다. 또한 베이스 수지에 테르펜 수지, butyl benzyl phthalate, 파라핀왁스 등을 첨가하여 접착제를 구성함에 따라 유변학적 거동도 쉽게 조절될 수 있었다. 용융점도와 접착제 자체의 인장물성 결과에 따르면 사용된 CM831과 843P형 폴리아미드 수지를 약 75/25∼50/50의 무게비로 블렌딩함이 최적의 접착력을 나타내리라 평가되었다. 또한 steel간의 접착력 평가 결과 steel 표면의 거칠음 정도가 접착력에 직접 영향을 미치는 결과를 얻었다. Hot melt adhesive based on the polyamide resin was studied to improve the conventional hot melt adhesives such as ethylene-vinyl acetate which have inherent problems against creep and heat resistance. It was found that the terpolymer of nylon6, nylon66, and nylon12 or the nylon blend instead of nylon homopolymer was suitable base resin for hot melt adhesives, since the disruption of regularity in the polymer chains reduced the crystallinity, resulting in lower melting point and melt viscosity. Also, the rheological properties of the polyamide based hot melt adhesive could be controlled by the incorporation of terpene resin, butyl benzyl phthalate, and paraffin wax. The results of melt viscosities and tensile properties of adhesive itself indicated that the optimum adhesion properties could be obtained through the blending of CM831/843P resins with weight ratio 75/25∼50/50. The adhesion between steel and steel was tested by using lap shear geometry. It was found that the surface roughness of steel affected the adhesion strength.
전영식,장보윤,김준수,이진석,최철희,한문희 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.6
SiO x nanoparticles were synthesized by using an evaporation and condensation process involving induction melting of silicon (Si) chunks followed by the injection of a H2/Ar mixed gas into the melt. In particular, this research studied the effects of hydrogen gas on the nanoparticles’ microstructural and electrochemical properties, etc. During the microstructural analysis, regardless of H2 content, all the nanoparticles were observed to have random shapes; their average particle sizes were 30 ∼ 35 nm. However, a crystalline Si phase, even though it was a small amount, was formed when H2/Ar gas was injected. From the X-ray photoelectron spectroscopy (XPS) analysis, the amount of the SiO2 phase in SiO x decreased when the H2/Ar gas ratio was higher than 1.0 vol.%. Injected hydrogen produced a Si-H network in SiO x , and the Si-H concentration was independent of the amount of injected gas. Consequently, due to hydrogen incorporation, not only was a crystalline Si phase formed, but also the amount of the SiO2 phase decreased. In addition, Si-H bonds were formed in the nanoparticles. The crystalline Si phase and the relatively small amount of the SiO2 phase resulted in an enhancement of the Li-ion capacity when those nanoparticles were applied as an anode material for a Li-ion battery. Furthermore, cycle performance was improved even when hydrogen was incorporated. For the sample synthesized with 5.0-vol.% H2/Ar gas, the discharge capacity and the columbic efficiency at the 21 st cycle were 889.1 mAhg−1 and 95.0%, respectively.
미역쇠(Endarachne binghamiae)추출물의 멜라닌 생성 억제 효과
전영식,정유정,염종경,김용기,김수남 한국자원식물학회 2013 한국자원식물학회지 Vol.26 No.5
In this study, we investigated the effect of 88 marine algae extracts on melanin synthesis to develop newwhitening agents. Among varieties of marine algae tested, the ethyl acetate extracts from Endarachne binghamiae (EB),Scytosiphon lomentaria, Sargassum yezoense, Ecklonia cava and Sargassum fusiforme inhibited melanin synthesis inmelan-a cells. EB treatment showed the strongest inhibitory activity in melanin synthesis, compared with that of otherextracts. EB-mediated inhibition of melanin synthesis appeared to be associated with inhibition of α-glucosidase-dependentglycosylation of tyrosinase in melan-a cells. In addition, EB treatment did not affect mushroom tyrosinase or cell-extractedtyrosinase activity in vitro. Taken together, our findings suggest that anti-browning effect of EB on skin is mediated throughregulation of α-glucosidase activity and subsequent inhibition of tyrosinase activity and melanin synthesis, and furtherdevelopment of EB as a potential agent for skin whitening.
전영식,장보윤,김준수,이진석,최철희,한문희 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.4
SiO<sub>x</sub> nanoparticles were synthesized by using an evaporation and condensation process involving induction melting of silicon (Si) chunks followed by the injection of a H<sub>2</sub>/Ar mixed gas into the melt. In particular, this research studied the effects of hydrogen gas on the nanoparticles’ microstructural and electrochemical properties, <i>etc</i>. During the microstructural analysis, regardless of H<sub>2</sub> content, all the nanoparticles were observed to have random shapes; their average particle sizes were 30 ∼ 35 nm. However, a crystalline Si phase, even though it was a small amount, was formed when H<sub>2</sub>/Ar gas was injected. From the X-ray photoelectron spectroscopy (XPS) analysis, the amount of the SiO<sub>2</sub> phase in SiO<sub>x</sub> decreased when the H<sub>2</sub>/Ar gas ratio was higher than 1.0 vol.%. Injected hydrogen produced a Si-H network in SiO<sub>x</sub>, and the Si-H concentration was independent of the amount of injected gas. Consequently, due to hydrogen incorporation, not only was a crystalline Si phase formed, but also the amount of the SiO<sub>2</sub> phase decreased. In addition, Si-H bonds were formed in the nanoparticles. The crystalline Si phase and the relatively small amount of the SiO<sub>2</sub> phase resulted in an enhancement of the Li-ion capacity when those nanoparticles were applied as an anode material for a Li-ion battery. Furthermore, cycle performance was improved even when hydrogen was incorporated. For the sample synthesized with 5.0-vol.% H<sub>2</sub>/Ar gas, the discharge capacity and the columbic efficiency at the 21st cycle were 889.1 mAhg<sup>−1</sup> and 95.0%, respectively.