Unlike a thermoplastic, thermoset materials are cured such that they don’t soften when exposed to heat (at least up to a certain point). This curing step usually introduces a lot of crosslinks between polymer chains, which creates a rigid network. These materials are much more difficult to recycle, but are used where high-temperature stability is needed.
According to the EPA, in 2010 Americans only recycled eight percent of their plastic waste. We can do better. About seventy-five percent of the packaging we use is recyclable.