ELI5 Rubber Bands - why do they become brittle over time?

What are rubber bands actually made of? Why do they become brittle over time? Why is it near impossible to let go of a stretched rubber-band with both hands at the same time? Which drug cartel was spending a reported $2500 per month on rubber bands? ... we explain like I'm five Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: party-pupper, tdscanuck, jozer99, uhly, carlmmii,readdit___4score, and iklegemma To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Twitter: https://www.twitter.com/eli5ThePodcast/ or send us an e-mail: ELI5ThePodcast@gmail.com