Science Buddies: "Ask an Expert"

I am an engineering student conducting an investigation on the weakening of polyisobutylene (PIB) in an insulated glass unit (IGU). Essentially, the PIB began to weaken and reached a state where it began to seep out in only 2 years of being in the IGU. If anybody has any knowledge as to what may cause PIB to weaken at that rate please let me know. Any information will help.

The URL below is an image of a typical IGU

http://www.independentwindowrepair.com/ ... ss/igu.jpg

Thanks in advance https://www.sciencebuddies.org/science- ... =post&f=50#