To nilo:
So, basically, your experiment shows that the tensile strength of plastic is greater than 36 psi, since that is the pressure you attained without bottle failure. Regarding bottle bombs, you now need to determine what the tensile strength of a glass bottle is. As long as the tensile strength of a glass bottle is less than 36 psi, no bottle bombs!
Great experiment! As a material scientist, I am entertained by your experiment! Keep it up!
You should also consider a measure of yeast attenuation for each experiment. Measure the gravity of the sample before pressurization and after the experiment to determine exactly how much of the 3 or 6 grams of sugar was converted to CO2 and alcohol. The results will then be a bit more interesting. I do love to see how the pressure decreases with temperature, though! PV=nrT!