고분자의 Coextrusion에서 유동에 대한 비등온 효과

유봉렬; 정인재

Korean Journal of Rheology, Vol.6, No.2, 129-138, December, 1994

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고분자의 Coextrusion에서 유동에 대한 비등온 효과

Non-isothermal Effect on the Flow Behavior of Polymer Melts in a Coextrusion Die

유봉렬, 정인재

초록

공압출되는 sheet die에서 고분자 물질의 비등온 유동을 수치 모사하였다. 유변학적 식으로 power-law model을 사용하였고, 격자생성법을 이용한 유한차분법을 사용하였다. 수치계산을 통해 수축채널에서의 온도 분포를 구해 보고, 점도가 채널에서의 압력강하 및 신장속도에 미치는 영향을 알아 보았다. 압력강하는 외부 유체의 점도 및 heat dissipation의 영향을 크게 받았다. 신장속도는 외부 유체의 점도가 증가함에 따라 커진 반면, 내부 유체의 점도증가에 따라 감소하였고, heat dissipation에 의해 증가하였다.

The non-isothermal flow of polymeric fluids in a coextrusion sheet die was studied through numerical simulation. Power-law model was adopted as a rheological equation, and finite difference methods employing numerical grid generation was used. Through numerical calculation, the temperature distributions in a converging channel were obtained and the effects of viscosity on the pressure drop or the elongation rate were analyzed. The pressure drop is strongly affected by heat dissipation and the viscosity of outer fluid. The elongation rate is increased as the viscosity of outer fluid increases, but is decreased as the viscosity of inner fluid increases. The elongation rate is increased by heat dissipation.

Keywords:Coextrusion;non-siothermal;converging channel;power-law model;elongation rate;numerical simulation

[References]

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[1] Everage AE, Trans. Soc. Rheol., 19, 509 (1975)

[2] Waters ND, J. Non-Newton. Fluid Mech., 12, 85 (1983)

[3] Mitsoulis E, J. Rheol., 30, S23 (1986)

[4] Khomami B, J. Non-Newton. Fluid Mech., 36, 289 (1990)

[5] Su YY, Khomami B, J. Rheol., 36, 357 (1992)

[6] Uhland E, Polym. Eng. Sci., 17, 671 (1977)

[7] Basu S, Polym. Eng. Sci., 21, 1128 (1981)

[8] Sornberger G, Vergnes B, Agassant JF, Polym. Eng. Sci., 26, 682 (1986)

[9] Nordberg ME, Winter HH, Polym. Eng. Sci., 30, 408 (1990)

[10] Feigl K, Ottinger HC, J. Rheol., 38(4), 847 (1994)

[11] Fenner RT, "Principles of Polymer Processing," Chemical Publishing, New York (1979)

[12] Tordella JP, Trans. Soc. Rheol., 1, 203 (1957)

[13] Cogswell FN, "Polymer Melt Rheology," John Wiley and Sons, Inc., New York (1981)

[14] Tadmor Z, Gogos CG, "Principles of Polymer Processing," John Wiley and Sons, Inc., New York (1979)