Adhesion and cohesion

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00:00:00 Welcome
00:01:59 Adhesion and cohesion
00:02:34 Abstract
00:03:28 O2Q
00:03:53 Agenda
00:05:02 Difference between cohesion and adhesion
00:06:27 Gecko Climb
00:06:27 Does it involve burdock-like attraction?
00:06:58 … like the “Hook and loop” or “touch” fastener
00:07:32 US Patent
00:08:02 Why and how can a gecko walk on the ceiling?
00:08:47 Why and how can a gecko walk on the ceiling?
00:09:10 Why and how can a gecko walk on the ceiling?
00:09:34 Why and how can a gecko walk on the ceiling?
00:10:23 Healed by a gecko
00:10:48 DARPA
00:11:35 Gecko’s foot – Chapter 4 “Clinging to the ceiling”
00:12:08 What interests me about the gecko’s foot?
00:13:05 Rumpf – the classic picture….
00:14:21 Attraction also on the macroscopic scale!From my bedroom window in the UK…
00:14:41 And where did I live? Wilton Place, Dymock
00:15:03 Strength of adhesion – amended and original
00:16:28 Dry analysis
00:16:51 Hans Rumpf
00:17:24 Hans Rumpf – Karlsruhe/Clausthal
00:17:52 Rumpf – the classic papers
00:18:35 Rumpf – 1 - 1962
00:19:32 Rumpf – adapted by Clyde Orr in “Particulate Technology” The Macmillan Co., (1966)
00:20:03 Rumpf – comparison of various adhesion mechanisms
00:20:58 General considerations
00:22:13 Key modern day players
00:22:54 Kelcey L. Eccleston & Kelly T. Miller Department of Metallurgical & Materials Engineering Colorado School of Mines Particle pull technique
00:23:59 slide34
00:23:59 Results Analysis: Force
00:24:53 Van de Waals forces
00:25:26 TiO2
00:26:43 Adhesion forces
00:28:01 Some examples of the strength of adhesion
00:29:40 Early history
00:31:40 Hamaker’s microscopic theory
00:32:44 Hamaker-Lifshitz-van der Waals
00:33:10 Attractive (van der Waals) and inertial forces
00:33:53 Attractive (van der Waals) and inertial forces
00:34:38 Attractive (van der Waals) and inertial forces
00:35:18 Van der Waals – effect of changing contact area
00:36:26 Van der Waals – effect of changing contact area
00:37:03 Electrostatic – or tribological effect
00:37:51 Rumpf – building bridges
00:38:19 Liquid bridges – capillary attraction – not on the moon
00:39:14 F M Etzler, M N Uddin “Powder Technology and Pharmaceutical Development: Particle Size and Particle Adhesion” KONA Powder and Particle Journal, 30, 125 – 143, (2013)
00:40:14 Solid Bridges
00:40:39 Solid bridges
00:41:09 Solid bridges
00:42:17 Solid-solid diffusion
00:43:16 Fick’s Law of diffusion
00:43:53 Fick’s Law of diffusion
00:44:45 Fick’s Law of diffusion
00:45:01 Fick’s Law of diffusion
00:45:46 Bulk/Primary: solid bridging; room temperature sintering
00:46:10 Bulk/Primary: solid bridging; room temperature sintering
00:46:50 Bridging will always occur - in the dry state!
00:47:12 Powders are a problem!Kendall
00:48:08 Inertial and van der Waals forces…..
00:48:40 Dissolution
00:49:00 Dissolution
00:49:54 Adhesion forces - dry millingTheoretical limit of a ball mill
00:51:02 O2Q
00:51:32 K. Eric Drexler
00:52:03 Ladybug - 35 mgElephant – cow – not bull – 3500 kg
00:52:42 References
00:53:22 Thank you!
00:53:51 Thank you for your attentionAny questions?Please type your questions in using the Q&A panel on the right side of your screen
01:05:24 Contact Information
The basis of agglomeration and aggregation is the attraction that particles and particle groups have for one another. We'll outline the various forms of atttaction (van de Waals, capillary etc ) and thus show how a gecko can walk on the ceiling.