화학공학소재연구정보센터
Korean Journal of Rheology, Vol.10, No.1, 14-23, March, 1998
PS/PP와 EPDM/PP 블렌드의 유변학적 거동에 미치는 계면의 영향
Effects of Interface on the Rheological Behaviors of PS/PP and EPDM/PP Polymer Blends
초록
비상용성 고분자 블렌드계인 PS/PP와 EPDM/PP의 유변학적 거동에 미치는 계면의 영향을 알아보았고, 그 실험 결과를 Park & Lee 모델과 비교하였다. PS/PP와 EPDM/PP 블렌드계에서의 계면에 의한 전단 응력과 법선 응력차에의 기여도는 κ와 λ(1-μ), 두 개의 변수에 의해 잘 설명되었다. 특히, 계면의 탄성적인 효과와 관련있는 법선 응력차 항이 전단 응력 항보다 더 뚜렷하게 나타났다. 30PS/70PP 블렌드 조성에서는 블렌드의 유변학적 특성이 주로 연속상을 이루는 고분자에 의해 좌우된 반면에, 50PS/50PP블렌드조성에서는 계면에 의한 영향이 더 두드러지게 나타났다. 이것은 50/50 블렌드 조성에서 계면의 넓이가 증가한 것과 관계 있다. 그러나 EPDM/PP 블렌드계에서는 계면에 의한 응력 항들이 모두 PS/PP블렌드계의 그것보다 매우 큰 값을 가졌지만, 그 상대적인 비를 나타내는 κ값은 작았다. 이것은 블렌드를 구성하고 있는 순수한 성분의 법선응력차 값의 차이가 크기 때문이다. 또한, PS/PP 블렌드계에 대한 동적 계면장력을 Park & Lee 모델을 이용하여 예측해 보았다.
Interfacial contribution on the rheological behaviors of immiscible polymer blends was analyzed for polystyrene (PS)/polypropylene (PP) and ethylene-propylene-diene rubber (EPDM)/PP blends at steady shear flow. The observed rheological behavior was compared with Park and Lee model. Both shear stress and normal stress difference due to the interfaces were well described by two parameters, κ and λ(1-μ). Especially, the normal stress difference terms which are related to elastic effect of the interfaces were more apparent than shear stress terms. In 30PS/70PP blends, the blend property was mainly determined by pure component's contribution. The interfacial contribution was more dominant at 50PS/50PP blends, which is due to the increased interfacial area. However, for EPDM/PP blends which has very elastic dispersion phase, the relative magnitude of interfacial contribution was small compared with pure component's contribution, even though it is still large compared with other blend systems. The blend properties were mainly determined by pure component's contribution when the original difference in first normal stress difference of pure components was too high. Park and Lee model was also successfully used to estimate the dynamic interfacial tension of PS/PP blend.
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