종이의 수분 확산 연구: 비정상 상태 흡습 동특성

윤성훈; 이병철; Sung Hoon Yoon; Byung Chul Lee

Journal of the Korean Industrial and Engineering Chemistry, Vol.13, No.7, 666-671, November, 2002

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종이의 수분 확산 연구: 비정상 상태 흡습 동특성

Molecular Diffusion of Water in Paper: Unsteady-State Moisture Sorption Dynamics in Paper Substrates

윤성훈^†, 이병철 ¹

한국조폐공사 기술연구소 제지연구실, 대전 305-713
¹한남대학교 공과대학 화학공학과, 정보산업대학원 제지화학공학과, 대전 306-791

Sung Hoon Yoon^†, and Byung Chul Lee¹

[email protected], Korea Mintion and security Printiong Corporation, Daejeon 305-713, Korea
¹Department of Chemical Engineering, College of Engineering, Department of Paper Chemical Engineering, Graduate School of Information Industry, Hannam University, Daejeon 306-791, Korea

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초록

흡수지와 여과지 시료를 사용하여 종이 내에서의 비정상 상태 수분 흡습 실험과 수분 확산 거동의 해석을 통하여 종이의 섬유영역에 대한 수분확산 특성을 연구하였다. 종이의 표면으로부터 내부로의 수분이동은 Fick형 수분확산으로 간주하였으며, 종이의 두께방향으로의 기하학적 대칭구조를 가진 일차원적 확산이라고 가정하였다. 완전히 건조시킨 종이를 항습조건에 노출시켜 시간에 따른 중량 변화를 측정하였으며 이를 비정상상태 수분 확산 모델에 적용시킴으로서 종이에서의 섬유상-수분확산계수를 결정하였다. 종이에서의 수분 흡습-확산 거동은 노출시간의 제곱근에 비례하는 Fick형 확산 특성을 보여주었으며, 흡수지와 여과지는 각각 약 10^-6 cm²/min 및 10^-7 cm²/min 크기의 섬유상-수분확산계수 값을 보여주었다. 종이의 섬유상 수분확산계수는 종이의 공극율이 0에 수렴했을 때의 이론적 유효-수분확산계수의 값에 해당하였으며, 종이의 수분 흡습 실측치와 모델 수치해는 흡습-확산 과정의 초기 단계에서 일치하였다.

The unsteady-state mositure soprtion and diffusion throuth cellulosic fibers in blotting and filter paper specimens were characterized from moisture sorption experiments and analytical modeling. The moisture transport through the paper was considered as a Fickean-type of diffusion process, and was assumed to be a one-dimension diffusion through the thickness, or the z-direction of the sheet with a symmetrical geometry. The moisture sorption uptake of the paper was obtained by exposing a thin dry paper sample to an environment with a constant humidity and constant temperature condition. Then, the fiber-phase moisture diffusion coefficient of the fiber was determined by correlating the experimental results with the unsteady-state diffusion model. The moisture sorption and diffusion behavior of paper fibers showed the characteristics of a Fickean-type diffusion process with the moisture uptake propertional to the square root of time. The fiber-phase moisture diffusion coefficients of paper samples were determined to have an order of magnitude of 10^-6 cm²/min ~10^-7 cm²/min. The fiber-phase moisture diffusion coefficient was found to be equivalent to the effective diffusion coefficient of the paper at an extreme limit of zero porosity. The fiber-phase moisture diffusion coefficient obtained from the numerical solution of the model agreed with that obtained from the experiment only in the initial stage of the moisture uptake process.

Keywords:paper;fiber-phase diffusion;moisture sorption;diffusion coefficient;fick

[References]

Casey JP, Pulp and Paper Chemistry and Chemical Technology, Wiley, vol. 3: 1548, 1889 (1981)
Liang B, Fields RJ, King CJ, Drying Tech., 8, 641 (1990)
Ahlen AT, TAPPI J., 53, 1320 (1970)
Yoon SH, Jeon Y, Ow SK, Seo YB, J. Korea Tappi, 30, 59 (1998)
Yoon SH, Jeon Y, J. Korea Tappi, 30, 46 (1998)
Yoon SH, Jeon Y, Park JM, J. Korea Tappi, 31, 61 (1999)
Alfrey T, Gurnee EF, Lloyd WG, J. Polym. Sci. C: Polym. Lett., 12, 249 (1966)
Crank J, Park GS, Diffusion in Polymers, Academic Press, New York (1988)
Marom G, The Role of Water Transprot in Composite Materials in Diffusion In and Through Polymers, W. Vieth (editor), Hanser Publishers, Munich, 341 (1979)
Geankoplis CJ, Transport Processes and Unit Operations, Prentice Hall, New Jersey, 426 (1993)
Shewmon PG, Diffusion in Solids, J. Williams Book Co., Jenks, OK, 6 (1983)
Crank J, The Mathematics of Diffusion, Clarendon Press, Oxford, 90 (1956)
Lin SH, Int. J. Chem. Sci., 28, 1151 (1990)
Ramarao BV, Chatterjee SG, Moisture Sorption by Paper Materials under Varing Humidity Conditions in Transaction of The 11th Fundamental Research Symposium, C.G. Baker (editor), Vol. 2, 703, Surrey, UK, September (1997)

[Referenced By]

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[1] Casey JP, Pulp and Paper Chemistry and Chemical Technology, Wiley, vol. 3: 1548, 1889 (1981)

[2] Liang B, Fields RJ, King CJ, Drying Tech., 8, 641 (1990)

[3] Ahlen AT, TAPPI J., 53, 1320 (1970)

[4] Yoon SH, Jeon Y, Ow SK, Seo YB, J. Korea Tappi, 30, 59 (1998)

[5] Yoon SH, Jeon Y, J. Korea Tappi, 30, 46 (1998)

[6] Yoon SH, Jeon Y, Park JM, J. Korea Tappi, 31, 61 (1999)

[7] Alfrey T, Gurnee EF, Lloyd WG, J. Polym. Sci. C: Polym. Lett., 12, 249 (1966)

[8] Crank J, Park GS, Diffusion in Polymers, Academic Press, New York (1988)

[9] Marom G, The Role of Water Transprot in Composite Materials in Diffusion In and Through Polymers, W. Vieth (editor), Hanser Publishers, Munich, 341 (1979)

[10] Geankoplis CJ, Transport Processes and Unit Operations, Prentice Hall, New Jersey, 426 (1993)

[11] Shewmon PG, Diffusion in Solids, J. Williams Book Co., Jenks, OK, 6 (1983)

[12] Crank J, The Mathematics of Diffusion, Clarendon Press, Oxford, 90 (1956)

[13] Lin SH, Int. J. Chem. Sci., 28, 1151 (1990)

[14] Ramarao BV, Chatterjee SG, Moisture Sorption by Paper Materials under Varing Humidity Conditions in Transaction of The 11th Fundamental Research Symposium, C.G. Baker (editor), Vol. 2, 703, Surrey, UK, September (1997)