HWAHAK KONGHAK, Vol.29, No.1, 73-80, February, 1991
Multiple Reaction Kinetics에 의한 핏치로부터 메조페이스 형성의 해석
Analysis of Mesophase Formation from Pitch by Multiple Reaction Kinetics
초록
두 종류의 석유계 핏치를 410-450℃에서 열처리한 후 핏치의 벤젠가용분(R), 벤젠불용분/퀴놀린가용분(S), 퀴놀린불용분(C) 및 열처리시 저비점 휘발성분(V)의 계외 방출량을 측정하여 메조페이스 형성에 관한 속도론적 고찰을 행하였다. 열처리에 의한 메조페이스의 형성반응은 각 과정의 반응식을 각각 1차로 가정한 다음과 같은 복합반응모델(multiple reaction model)로 해석할 수 있었으며, 각 과정의 활성화 에너지는 납 사타르핏치(NTP)가 15-65kcal/mole, 직류아스팔트(SA)rk 29-61kcal/mole이었다.
활성화 에너지(E)를 고려하여, 방사용 메조페이슬 제조하기 위해서는 NTP는 E1이 E2, E4 보다 작으므로 낮은 온도에서 SA는 E1이 E2보다 작고 E4보다는 크기 때문에 반응초기에는 높은 온도, 후기에는 낮은 온도에서 열처리 하는 것이 적합하다.
Kinetic studies on the mesophase formation in the pitch were carried out. Naphtha tar pitch(NTP) and straight asphalt(SA) were heat-treated in the temperature range of 410-450℃. The weight loss(V) of the pitches during the reaction was measured and the heat-treated pitches were also fractionated into benzene solubles(R), benzene insolubles/quinoline solubles(S) and quinoline in-solubles(C). The kinetics of the mesophase formation can be analysed by the foolowing multiple reaction model in which the rate equation of each step is assumed to be first order:
The activation energies(E) of each step for NTP and SA were 15-65 and 29-61kcal/mole, respec-tively. The kinetic studies indicate that the following heat treatment conditions would be appropriate for preparing a spinnable mesophase:
- NTP : a low temperature since E1<E2 & E4 - SA : a higher temperature at an early stage and a lower temperature at a later stage since E4<E1<E2
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