Dispensing 공정 조건에 따른 액적의 변형과 액적 내 입자 이동에 관한 연구 : Study on Liquid Drop Deformation and Particle Migration in Liquid Drops in Dispensing Processes
- 발행기관 고려대학교
- 발행년도 2007
- 학위수여년월 2007. 2
- 학위명 석사
- 학과 대학원 화공생명공학과 화공생명공학전공
- 식별자(기타) DL:000018551436
- 서지제어번호 000045358298
초록/요약
In this study, dispensing and spreading behavior of fluid on surface while changing dispensing conditions were examined. Spreading behavior of Newtonian and non-Newtonian suspension and particle migration within them were also examined. Experiments were conducted for a wide range of experimental conditions and the results were analyzed qualitatively. In dispensing and spreading experiments of liquids without particles, the dispensing and spreading process of fluid on the surface and the break up time of fluid column were examined with altering experimental conditions such as pressure and dispensing height. For a polyacrylamide 200ppm + ethylene glycol + glycerin solution, higher pressure induced the higher kinetic energy of fluid drop which led to a larger drop diameter on the surface, and higher dispensing height does not necessarily result in the larger diameter due to the competition of kinetic energy and elasticity. The break up time of polymer solution was shorter when the dispensing height was higher. In the case of epoxy, moderate change of dispensing height hardly affected the diameter of drop due to the high level of viscous dissipation. When using a syringe tip with large inner diameter, an excessive amount of epoxy was dispensed, and the fluid column buckled, flowed down spirally and eventually entrapped air bubbles inside the drop. The break up time of epoxy was found to be longer when dispensed at a higher height. In experiments of the spreading of suspensions, Newtonian and non-Newtonian suspensions were used to investigate the effect of rheological and surface properties on particle migration and distribution. The particle suspension dispersed in the mixture of ethylene glycol and glycerin, a Newtonian fluid, showed almost uniform particle distribution within the region of about 90% of the drop diameter. Polymeric suspensions dispersed in the 1000 ppm polyacrylamide solution in ethylene glycol and glycerin and the aqueous solution of 10000ppm polyacrylamide showed almost the same particle distributions but slightly different evolutions in drop diameter. Suspensions dispersed in an aqueous solution of 5000ppm xanthan gum, which has strong shear thinning effect, showed concentration of particles to the center of drop. Contact angle effect on the particle distribution was examined by using glass and Teflon surfaces. When the static contact angle between fluid and surface is low, the base solution of suspension percolated throughout particles to match the contact angle, but particles stayed in their initial places due to lack of energy to move and lower liquid level than the particle diameter at the boundary. The behavior resulted in the partial distribution of particles within the drop. On the other hand, when the contact angle is high, the percolation was suppressed and the particles were distributed all over the drop.
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Abstract
List of Tables
List of Figures
1. 서론
2. Dispensing과 Spreading 과정
3. 입자를 포함하지 않는 용액의 Dispensing과 Spreading
3.1. 실험
3.1.1. 시료
3.1.2. 실험장치
3.1.3. 실험 방법
3.2. 실험 결과
3.2.1. Polyacrylamide 200ppm + Ethylene Glycol + Glycerin Solution
3.2.1.1. 토출 압력 변화
3.2.1.2. 토출 높이 변화
3.2.2. Epoxy
3.2.2.1. 토출 높이 변화
3.2.2.2. 실린지 팁 내경 변화
3.2.3. Break Up Time
4. 현탁액의 Spreading
4.1. 실험
4.1.1. 시료
4.1.1.1. 용액
4.1.1.2. 입자
4.1.1.3. 현탁액
4.1.2. 실험장치
4.1.3. 실험방법
4.2. 실험결과
4.2.1. 뉴튼성 유체
4.2.1.1. Ethylene Glycol + Glycerin
4.2.2. 비뉴튼성 유체
4.2.2.1. Polyacrylamide 1000ppm + Ethylene Glycol + Glycerin
4.2.2.2. Polyacrylamide 10000ppm + Distilled Water
4.2.2.3. Xanthan Gum 5000ppm + Distilled Water
4.2.3 Contact Angle 차이에 따른 Spreading 현상과 입자 분포의 차이
5. 결론
References
List of Tables
Table 1. Experimental conditions of PAAm 200ppm + EG + GL solution
Table 2. Experimental conditions of Epoxy
Table 3. Surface tension and static contact angle on glass surface of pure solutions
Table 4. Experimental conditions for spreading experiment of suspensions
Table 5. Static contact angle of xanthan gum 5000ppm + DW suspension on glass and Teflon surface
List of Figures
Fig. 1. Four phases of spreading process defined by Rioboo et al. Each line represents spreading behavior which can occur according to properties of fluids and surfaces.
Fig. 2. Viscosity and storage/loss moduli of PAAm 200ppm + EG + GL solution and epoxy
Fig. 3. Schematic diagram of dispensing experimental apparatus
Fig. 4. Example of image processing of the drop on the surface
Fig. 5. Flow rates grow linearly according to increasing pressure and pressurizing time. Positive flow rate at the pressurizing time of 0 sec is due to pendent drop at syringe tip.
Fig. 6. Images of dispensing and spreading process of PAAm 200ppm + EG + GL solution at 3atm, 4atm and 5atm.
Fig. 7. Time evolution of diameter and height of PAAm 200ppm + EG + GL drop according to dispensing pressure change
Fig. 8. Images of dispensing and spreading process of PAAm 200ppm + EG + GL solution at 5mm, 10mm and 15mm from the surface.
Fig. 9. Time evolution of diameter and height of PAAm 200ppm + EG + GL solution according to dispensing height change
Fig. 10. Images of dispensing and spreading process of epoxy solution at 5mm, 10mm and 15mm from the surface.
Fig. 11. Time evolution of diameter and height of epoxy drop according to dispensing height change
Fig. 12. Images of dispensing and spreading process of epoxy with 0.33mm, 0.51mm and 0.84mm ID syringe tip.
Fig. 13. Time evolution of diameter and height of epoxy drop according to syringe ID change
Fig. 14. Different break up behaviors of PAAm 200ppm + EG + GL solution and epoxy
Fig. 15. Break up time of PAAm 200ppm + EG + GL solution and epoxy according to dispensing height change
Fig. 16. Viscosity and storage/loss moduli of pure solutions
Fig. 17. Schematic diagram of experimental apparatus
Fig. 18. Images of the drop of EG + GL pure solution and suspension on the glass surface. The circle in the image indicates the range which base solution has spread.
Fig. 19. Time evolution of drop diameter of EG + GL pure solution and suspension
Fig. 20. Images of the drop of PAAm 1000ppm + EG + GL pure solution and suspension on the glass surface
Fig. 21. Time evolution of drop diameter of PAAm 1000ppm + EG + GL pure solution and suspension
Fig. 22. Images of the drop of PAAm 10000ppm + DW pure solution and suspension on the glass surface. The circle in the image indicates the range which base solution has spread.
Fig. 23. Time evolution of drop diameter of PAAm 10000ppm + DW pure solution and suspension
Fig. 24. Images of the drop of xanthan gum 5000ppm + DW pure solution and suspension on the glass surface
Fig. 25. Time evolution of drop diameter of xanthan gum 5000ppm + DW pure solution and suspension
Fig. 26. Rearranged particles at the tip of capillary
Fig. 27. Different static contact angle of xanthan gum suspension on glass and Teflon surface
