Talk:Cohesion (chemistry)

message: Needs a LOT of work. Example: photo of Hg caption.  The container it is in "sticks together" for the same reason! The reason the Hg "balls up" (lay term) is because the cohesive forces (within the Hg and within the glass) exceed the adhesive forces between the Hg and the glass.
What is all the stuff about construction materials doing here?Softwarestorage (talk) 23:33, 18 August 2008 (UTC)
replies: text: That doesn't match up with the adhesion article. And why did you remove the part about industrial use...? Sorry, I don't know much about chemistry, so I may be wrong... suzumebachi٭secret 18:37, 14 July 2009 (UTC)
replies: text: Talking to the wrong person, no wonder it didn't make sense... Sorry! suzumebachi٭secret 18:39, 14 July 2009 (UTC)
thread_title: Complete overhaul

message: Nothing wrong with this section as such - but it's describing 'cohesion' in a 'building sense' not a chemical sense - and as such many of the examples are those of adhesion eg paint.
==Industry applications==
The construction industry uses many materials that undergo a phase transition during installation and use. These include, but are not limited to the following:
*caulking
*firestop mortar
*concrete
*plaster
*spray fireproofing
*paint
Often, these building materials are required not just to be cast and occupy space. They must also stick and maintain a certain thickness or space. Paint typically does not require as much cohesion as caulking, as paint is applied much more thinly. High quality firestop mortars require extreme cohesion with the adhesion because they are often used in large wall openings, where the mortar must not only adhere to adjacent materials but also hold itself up, forming a wall in the plastic state, which must hold long enough to cure and convert to the solid state. The thicker the application, the more cohesion is required.
I've pasted it above - maybe someone else can work on it - most of may be better found in another article.
eg the sticking together of mortar is cohesion, but because of the phase change other things hold it together - such as interlocking crystals - I think it't best to leave out for now.
Specifically the paragraph has it right when it says The construction industry uses many materials that undergo a phase transition
But these phase transitions include precipitation, crystallisation both of which give rise to more than just cohesive properties. As for paint - the binder (which is effectively glue) holds it together, holds the pigment in, and sticks it to the wall - the binders are usually/often long chain polymers which will be sticking primarily by adhesive forces, as well as interlocking, in addition to cohesion.
I think a rewrite explaining the need for cohesion to hold together the bulk of polycrystalline materials like plaster of paris, fire bricks is necessary - though it requires citations - specifically proof that the cohesive force is the major force.
Additionally all fired materials must be held together at least a little by sintering which is not cohesion.
I think plaster of paris is probably the best example of a cohesively held together builfing material - again with the possible disclaimer of interlocking.83.100.250.79 (talk) 18:38, 14 July 2009 (UTC)
thread_title: section removal

message: That's a good idea,actually adhension and cohesion are co-related,and if we can understand one better,other can be understood nicely.And it seems easy to contrast and compare between two.  — Preceding unsigned comment added by Anki112279 (talk • contribs) 06:16, 23 October 2014 (UTC)
replies: text: I oppose a merger. I think adhesion requires an adhesive. Biscuittin (talk) 20:02, 25 November 2014 (UTC)
thread_title: Merging

message: Maybe this picture is a better example for cohesion than the one with the Equisetum. In the picture with the Astronaut we have 100% cohesion. Hive001 contact 08:40, 2 May 2010 (UTC)
thread_title: Picture

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thread_title:  [[:File:Clayton Anderson zero g.jpg]] to appear as POTD soon 

message: Substituted at 11:59, 29 April 2016 (UTC)
thread_title: Assessment comment