Announcement

Collapse
No announcement yet.

Corn Starch and Water

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Corn Starch and Water

    All sorts of tricks can be done with this stuff ..
    there are various videos on you tube with speakers and vibration devices .

    here's just one vid to show the properties of the stuff.

    http://www.youtube.com:80/watch?v=amfjWWMg9c0&NR=1

    but other than party tricks ..I'm sure we could put it to a more ingenious use ..


    HE HE ...now you can have sleepless nights thinking about it

    All the best.markj

  • #2
    Corn starch, water and bouillon makes a gravy but I don't think I would try to walk across it.
    Last edited by Carld; 12-17-2009, 03:56 PM.
    It's only ink and paper

    Comment


    • #3
      OMG! Add Carl's post to the Bachelor Food thread!


      -=-=-

      The video is freaky. I remember similar from grade school. No one knew if the stuff was a solid or a liquid.
      Last edited by Tony Ennis; 12-17-2009, 04:25 PM.

      Comment


      • #4
        It is a thixotropic liquid, meaning it reacts in a non-linear fashion. So is ketchup but in the opposite way. Ketchup turns into a gel if not disturbed and thins if shaken. Corn starch and water becomes a liquid if not disturbed and gels when it is.
        Free software for calculating bolt circles and similar: Click Here

        Comment


        • #5
          Thats funny!
          Feel free to put me on ignore....

          Comment


          • #6
            I think the term is rheopectic for the shear thickening effect.

            Comment


            • #7
              You are correct but so is thixotropic. It's a more general term.

              Flow can induce reversible and irreversible structural changes in dispersions. The analysis of flow effects on microstructure and rheology remains one of the challenging problems in colloid science. The rheological manifestation of flow-induced structural changes is a variable viscosity. If the changes are reversible and time dependent, the effect is called thixotropy.
              http://www.sciencedirect.com/science...0d4a7d0ec18457
              Free software for calculating bolt circles and similar: Click Here

              Comment


              • #8
                Ketchup is thixotropic, it becomes more fluid when agitated. Cornstarch and water behaves in the opposite manner and is isotropic, it becomes firmer when agitated
                Jim H.

                Comment


                • #9
                  What you see is commonly refered to as a "non-newtonian fluid" characteristic
                  Liquid Plastic, like Polyethelene at 300 degrees becomes a non-newtonian fluid as well.
                  Say you have a half full pail of it, and pour some more on top (in the middle) it will not surge right to the bottom of the pail as water does ( or seen in a waterfall), but instead will flow out horizontally to the sides of the pail, and then down to the bottom.
                  You might say that the friction of one molecule against another is so great, that it is acutually easier to flow against a non plastic surface like air or the steel pail.
                  This makes mixing Plastics extremely difficult and gives the polymers memory of what they have been exposed to.
                  You might say they do not heal their wounds easily.

                  Rich
                  Green Bay, WI

                  Comment


                  • #10
                    Ketchup is thixotropic, it becomes more fluid when agitated. Cornstarch and water behaves in the opposite manner and is isotropic, it becomes firmer when agitated
                    Isotropic means the same in all directions, without a preferred direction. It has nothing to do with non newtonian fluids.
                    Free software for calculating bolt circles and similar: Click Here

                    Comment


                    • #11
                      Originally posted by JCHannum
                      Ketchup is thixotropic, it becomes more fluid when agitated. Cornstarch and water behaves in the opposite manner and is isotropic, it becomes firmer when agitated
                      We prefer custard to play with over here, tastes better!
                      you can al;so make some interesting body armour out of non-newty stuff
                      throw in some synthetic spider silk and itll stop a bus lol
                      mark

                      Comment


                      • #12
                        Shear thinning fluids are a fact of my life as a drilling engineer. Drilling fluids and cements are intentionally designed to be shear thinning and to develop high early gel strengths for special applications like "thief" zones for example.

                        FWIW, cements are also designed for setting/curing times. It's a bit tricky though, screw up the mix, miss-guess the temperature, or use an incompatible mix water and someone ends up chipping cement out of their equipment... Bin dere....
                        Design to 0.0001", measure to 1/32", cut with an axe, grind to fit

                        Comment


                        • #13
                          Originally posted by Evan
                          Isotropic means the same in all directions, without a preferred direction. It has nothing to do with non newtonian fluids.
                          Not so, this is just one of many explanations of the difference between isotropic fluids and thixotropic fluids. It just happens that cornstarch & water and ketchup are among the most common fluids displaying these characteristics.

                          http://fatlion.com/science/isotropy.html
                          Jim H.

                          Comment


                          • #14
                            The website you linked to is incorrect in the use of the term. When applied to a fluid the term Isoptropy simply means that the fluid has the same measured characteristics in all directions.
                            Free software for calculating bolt circles and similar: Click Here

                            Comment


                            • #15
                              You will have to convince a lot of people of that. It is a commom term in that application. The ketchup and cornstarch & water demonstration is standard demonstration used to display the two different characteristics.

                              A quick search of isotropic fluid+cornstarch will turn up dozens of hits defining the terms.
                              Jim H.

                              Comment

                              Working...
                              X