Why do balloons pop?

Answer 1

i thinks since its first of all filled w/ gas and it rubber well i hope this helps; The energy stored in the compressed air inside a balloon is not very large at all. Balloons create very little overpressure, apparently on the order of 5 or 6 mm of Mercury when inflated to normal size. On inflation, the pressure must be higher as the rubber just starts to stretch because, from our stress equations above: the modulus (stiffness) of the rubber is initially large, (it then drops off, to finally get VERY large with increasing strain) the balloon wall is initially thick, and the radius of the balloon is small. Pressure falls rapidly as the balloon grows in size. This follows from the stress/pressure relationship, and the stress/strain curve for latex. There is a well-understood differential equation applying to soap bubbles relating surface tension, bubble shape and internal pressure. The surface tension can be thought of as a *constant* hoop and axial stress (NOT a function of strain, as in latex). Two soap bubbles inflated to about the same size and connected with a pipe form a system that is not stable. One soap bubble will always collapse and the other will inflate. The smaller bubble size requires a higher air pressure than the larger bubble; it tries to develop the higher pressure by shrinking, but since the bubbles are connected by a pipe, shrinking just forces the air into the larger bubble. As the bubble size difference increases, so does the pressure difference generated to drive the air flow. This speeds up the collapse of the small bubble. Now, remember that the volume of a spherical soap bubble is proportional to the cube of its diameter. Visually, the process *appears* to speed up even more, because even for a constant air flow rate through the pipe, the diameter of the small bubble will be decreasing at a much greater rate than the large bubble diameter will be increasing. This can be demonstrated with balloons, but the size difference has to be rather noticeable before the process will begin. When it does begin, it can become rapid and it can suddenly halt. With balloons, this is a much more complex experiment than meets the eye because there are so many variables changing at once. The 500 - 600% strains make it a "large deflection" problem, in which we can't make any of the simplifying assumptions which we usually do. The geometry changes substantially, and latex displays highly nonlinear behavior. The sudden halt even shows up in ONE balloon when you are using 260's. Partially inflate a 260 and what do you get? a large diameter, thin wall, high stress bubble with 500 - 600% strain, a small diameter, thick wall, low stress nipple with but a few % strain, and a transition region between them. Note that each of these two distinct sections contains the same pressure! How is this possible? It's possible because this large deflection problem in nonlinear elasticity (remember the sigmoidal stress-strain curve?) has more than one stable solution! Amazing if I do say so myself! As balloons reach maximum expansion they get to a point where the latex runs out of stretch and gets stiff and resists further stretching. This is obvious in a fresh, overinflated balloon. It will become stiffer and get very rigid as all the latex molecules all become oriented in the tensile stress directions. This increase in stiffness will cause balloons, unlike soap bubbles, to increase in internal air pressure just before bursting.

Answer 2

Many things can cause a balloon to pop, including heat and sharp objects.