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| Particle Adhesion | |
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| Van der Waals Force | JKR and Other Adhesion Models | Particle Adhesion & Removal | Effects of Charge | Effect of Humidity | Ultrasonic and Megasonic Cleaning | |
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Effects of Charge Examples of Adhesion-Induced Deformations Quintessential JKR SystemsBurnham, Colton, and Pollock (Phys. Rev. Lett. 69, 144 (1992) measured the attractive force between an AFM cantilever tip and a flat graphite surface.They reported that the range of attractive forces was too great to be explained in terms of van der Waals forces. Horn and Smith (Nature 366, 442 (1993); Science 256, 362 (1992); J. Electrostatics 26, 291 (1991)) reported an increase in detachment force between two flat silica substrates, one of which had been coated with dimethyethoxysilane.The increase in adhesion was associated with a transfer of charge from one material to the other. Dickinson (see, for example, Fundamentals of Adhesion and Interfaces, Rimai, DeMejo, and Mittal (eds.), pp. 179-204 (1995) reported the emission of charged particles generated upon the fracture of a material (fractoemissions). PointsVan der Waals forces are electrodynamic and are expected to be short range.Under certain circumstances they may contribute significantly to adhesion.·There are long-range interactions that contribute to adhesion.These may be due to electrostatic interactions. ·There is evidence that adhesion has long-range contributions.If this is correct, is the JKR theory, which is based on contact mechanics, appropriate? Role of Electrostatic Interactions in Particle AdhesionConsider a spherical toner particle of radius R = 6 mm and q/m = 15 mC/g. ̃ q = 1.4 x 10-14 C. ̃ s = 3 x 10-5 C/m2.
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