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Is a latex balloon's maximum strain independent of thickness?

  1. Jun 11, 2016 #1
    Is latex balloon maximum strain independent of latex thickness?

    I have been in search of a latex balloon that is relatively small when deflated and very large when fully inflated. Standard balloons that reach the desired inflated dimensions are much larger deflated than I would like. Specifically, I would like a balloon that can reach inflated radius of ~3'. Although, I want the balloon's deflated radius not to exceed 3".

    Since I could not find an off-the-shelf balloon meeting the above requirement, I considered making my own balloon from latex. Perhaps if the latex was formed to create a ballon with ~3x the standard latex wall thickness, which would increase the maximum allowed internal pressure, I could meet my requirement. If the maximum strain of latex is independent of latex thickness, though, I don't think I will ever meet my requirement. A thicker balloon will require more pressure to stretch to a given dimension, but the maximum strain (stretch) before popping will remain unchanged. Is this true?

    Maybe someone is aware of a material with much higher maximum strain than latex?

  2. jcsd
  3. Jun 12, 2016 #2
    The strains are determined by the kinematics. If you assume a spherical balloon, going from 3" to 3' requires an isotropic stretch of 12 x in each in-plane direction of the latex. So the total area increases by a factor of 144. This means that the of the latex decreases by a factor of 144. Is a sheet of latex capable of sustaining isotropic in-plane stretches of 12x in each direction while decreasing in thickness by 144x? That would have to be determined experimentally.
  4. May 21, 2018 #3
    Thickness is independent in a perfect world (defect free film). To get 1200% elongation with this material is (to pardon the pun) a bit of a stretch. Softening the cure system will increase elongation but at the expense of tensile strength (and possibly elasticity). Removing defects is key - a double dip could help eliminate pinholes but a thicker film could increase the possibility of defects
  5. May 21, 2018 #4
    You realize that this thread is 2 years old, and that the OP hasn't been on Physics Forums since then?
  6. May 21, 2018 #5
    No and no. I was looking something up and came across this thread so thought I would contribute
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