Polymer(Korea), Vol.46, No.1, 22-29, January, 2022
고분자 분산제 혼합액에 분산된 탄소나노튜브의 응집과 분산액의 탄성 거동
Aggregation of Carbon Nanotubes Dispersed in a Liquid Mixture with Polymeric Dispersant and Elastic Properties of the Dispersion
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초록
다중벽 탄소나노튜브(CNT) 분산액의 탄성적 성질을 이용하여 CNT 입자의 미시적 응집구조에 대해 분석하였다. CNT 입자를 고분자 분산제가 혼합된 에틸렌글리콜에 분산시켜 얻은 분산액에 대해 저장 탄성률과 항복응력의 입자 농도 의존성에 관한 스케일링 이론을 적용하여 응집체의 프랙탈 차원를 비롯한 응집구조 변수들을 구하였다. CNT의 분산이 120 분까지 진행되면서 프랙탈 차원이 분산시간 30분일 때 1.92로부터 120분에서 1.28까지 지속적으로 감소하는 경향을 보임으로써 CNT 응집체가 엉겨 있는 형태에서 1차원적 선의 형태로 변해가는 것으로 나타났다. 다른 미시적 구조 변수들, 유변학적 물성과 전기전도도의 분산시간에 따른 변화도 프랙탈 차원의 변화에 부합하는 결과를 보였다.
Aggregates of multi-walled carbon nanotubes (CNT) were microscopically analyzed using elastic properties of their dispersion. Scaling theories based on the dependency of elastic modulus and yield stress on the CNT concentration were applied to the aggregated CNT particles suspended in ethylene glycol mixed with a polymeric dispersant. Using the scaling theories, we obtained structural parameters including fractal dimension of the aggregates. As milling time for CNT dispersion increases up to 120 min, the fractal dimension of the aggregates continuously decreases from 1.92 at 30 min to 1.28 at 120 min. This means that entangled shape of aggregates is turning into one dimensional linear shape as the dispersion time increases. It was found that overall trend of other structural parameters, rheological properties, and electrical conductivity with the dispersion time agreed with that of the fractal dimension.
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