We can crack molecules with temperature. We take oil out of the car that has 30,000 miles on it. It's really thin and pours really easy. You can still see your finger even though it's black oil. You stick your finger in the same kind of oil for a car, that is new and it's thick and syrupy.
Heat breaks oil down.
There's little parts and pieces of metal in that oil and carbon buildup also. So molecules actually crack and break apart with temperature in all substances. Just sitting here, ammonia nitrate fertilizer will deteriorate. Then we put it out in UV light and that UV light is absorbed by it too and breaks it apart by the absorption of protons of light. It's hard to get microbes to eat the longer chains.