• 폴리머
• /
• 제38권3호
• /
• pp.286-292
• /
• 2014

에너지 고분자인 poly(BAMO-AMMO)와 유사한 특성을 갖는 폴리에틸렌 플라스토머인 Exact를 고분자 결합제로, RDX(research department explosive)와 유사한 특성을 갖는 dechlorane을 충전제로 사용한 고농축 복합화약 시뮬란트 현탁계의 유변물성을 연구하였다. 회분식 용융혼련기를 사용하여 현탁계의 혼화거동을 조사하였는데 상당한 점성소산열이 발생하였다. 충전율이 70 v% 이상에서는 토크의 지속적인 감소가 있었는데 이는 벽면 미끌어짐 현상에 기인한다고 사료되었다. SEM 관찰 결과 충전제 입자들은 잘 분산되어 있었고 혼화 조건의 영향은 크지 않은 것으로 판단되었다. 현탁계의 뚜렷한 전단박화(shear thinning) 특성으로 인하여 낮은 전단속도의 평판-평판 레오미터에서 측정이 어려운 고충전 현탁계도 높은 전단속도의 모세관 레오미터에서 유변물성 측정이 가능하였다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
• /
• pp.456-461
• /
• 2017

본 연구에서는 이산화규소를 젤화제로 사용한 니트로메탄 젤 추진제의 유변학적 특성을 분석하였다. 니트로메탄 젤은 나노 또는 마이크로 입자 크기의 젤화제를 각각 5 wt%, 6.5 wt%, 8 wt% 함량으로 첨가하여 제작되였으며 점도 측정 실험은 회전형 점도계를 이용하여 측정을 수행하였다. 제작된 젤 추진제는 항복응력이 존재함을 확인하였고 측정 범위 전 구간에서 전단박화 거동을 보이며 나노 크기의 젤화제를 첨가한 젤 추진제의 경우 마이크로 크기 대비 낮은 전단속도(1 ~ 100 1/s) 영역에서 높은 점도를 보였다. 또한 니트로메탄 젤 추진제의 경우, Herschel-Bulkley 모델 보다는 Teipel과 Forter-Barth가 제시한 모델을 사용하는 것이 적합함을 확인하였다.

• 한국수산과학회지
• /
• 제30권3호
• /
• pp.329-333
• /
• 1997

국내산 미역포자엽, 다시마, 톳, 모자반에서 추출한 부분 정제 fucoidan의 유동특성을 측정하였다. 겉보기 점도는 모자반, 다시마, 톳, 미역포자엽 순으로 높았으며 특히 전단속도 1,500 1/s에서 미역포자엽의 용액 $(5\%)$의 겉보기 점도는 2.2mPa.s로 매우 낮았다. 전시료 모두 유동지수 1이하의 의가소성 유체의 성질을 나타내었으며 시료의 농도가 증가함에 따라 의가소성이 증가하였다. 온도에 따른 활성화 에너지는 전단속도 1,500 1/s에서 톳 $8.269\times10^6$, 다시마 $7.498\times10^6$, 미역포자엽 $7.141\times10^6$, 모자반 $6.677\times10^6\;J/kg.mol$로 낮아 온도 의존성이 적었다. 또한 설탕 첨가시는 부분 정제 fucoidan의 점도가 증가한 반면에 소금 첨가시는 변화가 없었다.

• Bulletin of the Korean Chemical Society
• /
• 제35권5호
• /
• pp.1469-1478
• /
• 2014

Use of acetonitrile in electrolytes promotes better operation of supercapacitors. Recent efforts show that electrolytes containing acetonitrile can also function in a wide range of operating temperatures. Therefore, this paper addresses the dielectric relaxation processes, structure and dynamic properties of the bulk acetonitrile at various temperatures. Systems of acetonitrile were modeled using canonical ensemble and simulated by employing Molecular Dynamics method. Results show that interactions among the molecules were correlated within a cut-off radius while parallel and anti-parallel arrangements are observed beyond this radius at relatively high and low temperatures respectively. Furthermore, effects of C-C-N and C-H bending modes were greatly appreciated on the power spectral density of time rate change of dipole-dipole correlations whereas frequency shifts were observed on all modes at the lowest temperature under consideration. Linear variations with temperature were depicted for reorientation times and self-diffusion coefficients. Shear viscosity was also computed with a good accuracy within a certain range of the temperature as well.

• 펄프종이기술
• /
• 제43권5호
• /
• pp.11-16
• /
• 2011

This study was aimed to apply thermochromic and photochromic pigments to coating color and to develop a speciality functional coated layer. Two special pigments were added to a conventional coating color. The effects of the special pigments on coating color properties such as water rerention, low-shear viscosity were evaluated. Also the color changes of coated paper was observed under various circumstances. The results showed that the special pigments didn't influence the coating color properties. The coated paper with the special pigments showed four different colors, under various circumstances, implying that thermochromic and photochromic pigments can be used to produce a security paper.

• 한국인쇄학회:학술대회논문집
• /
• 한국인쇄학회 2007년도 추계 학술논문 발표회
• /
• pp.59-64
• /
• 2007

We have manufactured low-curable silver pastes for gravure printing out of roll to roll printing process. When printing, the pastes be used different silver powder shape because of the printing characteristics. The pastes were prepared with silver powder by silver powder shape, polyester resin, solvent and homogenized on a standard three-roller mill. And the pastes exhibited a shear-thinning flow at viscosity profile. Moreover the adhesive strength and resistivity of silver film had good characteristics. With the manufactured paste in this study, RFID antenna circuit had flexible is manufactured and it had $10^{-4}{\sim}10^{-5}{\Omega}{\cdot}cm$.

• Korea-Australia Rheology Journal
• /
• 제21권3호
• /
• pp.185-191
• /
• 2009

Polystyrene/multi-walled carbon nanotube (PS/MWCNT) composites were prepared by the use of latex technology. The monodisperse PS latex was synthesized by an emulsifier-free emulsion polymerization from styrene/potassium persulfate/water system in the presence of ethanol. The MWCNTs were first treated with acid mixture to eliminate impurities, dispersed in deionized water driven by ultrasonicator, and then mixed with the PS latex. From these mixtures, PS/MWCNT composites were prepared by freeze-drying and subsequent compression molding. In the small-amplitude oscillatory shear experiments, both complex viscosity and storage modulus increased with increasing MWCNT content. A pronounced effect of MWCNT content was observed, resulting in larger storage modulus and stronger yield behavior at low frequencies when compared to unmodified PS. It showed a transition from viscous to elastic behavior with increasing MWCNT content. Over the MWCNT content of 3 wt%, the storage modulus was higher than the loss modulus across all frequencies.

• Korea-Australia Rheology Journal
• /
• 제20권4호
• /
• pp.227-233
• /
• 2008

High impact polystyrene (HIPS)/organoclay nanocomposites via in situ polymerization were synthesized and their rheological properties were investigated. For the study, two types of organoclays were used: a commercially available organoclay, Cloisite 10A (C10A), and a laboratory-prepared organoclay having a reactant group, vinylclay (ODVC). The X-ray diffraction and transmission electron microscopy experiments revealed that the HIPS/ODVC nanocomposite achieved an exfoliated structure, whereas the HIPS/C10A nanocomposite achieved an intercalated structure. In the small-amplitude oscillatory shear experiments, both storage modulus and complex viscosity increased with increasing organoclay. A pronounced effect of the organoclay content was observed, resulting in larger storage modulus and stronger yield behavior in the low frequency region when compared to neat HIPS. The crossover frequencies associated with the inverse of a longest relaxation time decreased as the organoclay content increased. Over a certain value of ODVC content, a change of pattern in rheological properties could be found, indicating a solid-like response with storage modulus greater than loss modulus at all frequencies.

• 펄프종이기술
• /
• 제29권4호
• /
• pp.28-35
• /
• 1997

Sole-binder formulation has been recently introduced to solve the problems of coating process and printability caused by use of natural polymer However, the decrease of natural polymer application causes another problem in paper coating. Therefore, synthetic thickener is used to get similar effect to natural polymer usage. In this study. low shear viscosity, dewatering of coating colors were measured to evaluate the performance of the alkali sensitive water retention and rheology modifiers. The effects of alkali sensitive thickener on the physical properties of coated paper and printability were also investigated. The gloss and printability of coated paper containing the synthetic flow modifier were similar or superior to those of CMC containing coated paper. This modifier was also effective to improve the problems caused by the use of starch. The results indicated that the flow modifier synthesized with alkali sensitive thickener can reduce the problems of natural polymer and could be a good substitute f3r a natural polymer.

• 수산해양기술연구
• /
• 제30권2호
• /
• pp.109-115
• /
• 1994

This paper presents a new concept to reduce turbulent frictional drag by injecting micro-bubble into near the buffer layer of turbulent boundary layer on flat plate. The concentrations of micro bubble distribution in the boundary was calculater by eddy viscosity equations in the governing equations. When near region of the buffer layer of turbulent boundary layer is filled with micro-bulle of air and viscous of the region is kept low, the velocity profile in the near region should be changed substantially. Then the Reynolds stress in the region becomes less, which guide to lower velocity gradient there. It results in reduction of velocity gradient at the viscous sublayer, which gives the reduction of shear stress at the wall.