Why do balloons get smaller?

First of all, we should understand that the air pressure in the balloon is higher than one atmosphere, which is enough to overcome the inward elasticity of the balloon after inflation. With the escape of air molecules, the air pressure becomes smaller, and the pressure on the surface of the balloon becomes smaller, so its reaction force-elasticity also becomes smaller, and the balloon will contract. So your question must meet the following conditions: 1. Balloon materials must be elastic, such as rubber, which is usually used to make balloons. If the balloon is welded with steel plates, it won't get smaller. Some balloons are made of fibers or plastic sheets, which have little elasticity, so they are not smaller, but deflated. The seal of the balloon has been stitched. If it is really seamless, the balloon will not get smaller. 3. The balloon is under normal temperature and pressure conditions. If placed in an environment with equal pressure, it will not become smaller. Balloon material is not airtight, but there are still many micropores through which gas molecules can diffuse outward and gradually become smaller. Especially for balloons filled with hydrogen, hydrogen balloons will deflate faster because hydrogen molecules are the smallest in the gas. The underwater pressure is very high. Because of the gap between molecules, under the action of high pressure, the gap between molecules becomes narrow.

The volume of gas decreases. Balloons will also get smaller. Balloons are made of rubber, which become thin and transparent after blowing enough air. At the same time, there are pores invisible to the naked eye. The pressure of the gas inside the balloon is much higher than that outside, and the gas slowly diffuses through the small holes, and it becomes smaller after a long time. Suppose the balloon is already in a tight state when it is one big and one small. Suppose Zhang Liwei A, the critical surface torn by balloon material. When the balloon is large, the gas pressure borne by the balloon material is almost uniform. When piercing, the gas velocity at the puncture site is much faster, which leads to the surface tension around the puncture site being in a state greater than A, being torn and quickly deflated, showing bursting. When the balloon is still very small, the surface tension near the puncture still increases, but basically it can't reach the critical value A, that is, the balloon can still maintain a state where only one small hole is punctured or the hole is slightly larger, so that the gas is exhausted. There would be no "explosion".