system
Given the following post, respond as if you're commenting on Reddit:
human
What is the difference between a polymer composite and polymer blend??
gpt
In brief, a polymer blend is multiple types of polymeric materials literally blended together with heat and screws. They aren't always single thermodynamic phases afterwards, but they usually are.  A polymer composite is usually a non-polymeric material mixed with or embedded into a polymeric material.  A good example of this is any so-called "carbon fiber" composite, where it is carbon threads weaved into a sheet of fabric, then soaked in glue. Another one is fiberglass composite which you might find in boats or light aircraft: fiberglass threads slathered in epoxy.