Final answer:
Polyvinyl chloride (PVC) and polytetrafluoroethylene (PTFE) are almost always nonflammable polymers used in various applications.
Step-by-step explanation:
Polyvinyl chloride (PVC) and polytetrafluoroethylene (PTFE) are polymers that are almost always nonflammable.
PVC is commonly used in pipes, window frames, cable insulation, and more. PTFE, also known as Teflon, is used in non-stick coatings, lubricants, and electrical insulation.
Both PVC and PTFE have high resistance to heat and are difficult to ignite, making them nonflammable polymers.