Are the molecules arranged differently by the different stresses as the latex is stretched?
Yes. when you stretch an uninflated 260 like a rubber band, you straighten out and line up the molecules in the direction that you are pulling. When you inflate a round balloon, the molecules are stretched equally in all directions tangential to the balloon wall because the stress in all tangential directions is the same. But when you inflate a 260, twice as many molecules (probably twice, I can’t really count ’em…) uncoil in the hoop direction as in the axial direction because of the 2:1 ratio of the stresses. Now to answer your question of why some 260’s break straight across, think of this. If there are twice as many molecules lined up with their strong direction in the hoop direction, it shouldn’t be that hard for a crack to overcome the weak Van Der Waals forces that hold those molecules against each other, right? Upon inflation, balloons get easier to see through primarily because light can pass in-between the straightened, oriented molecules, rather than getting lost in the ta
