You're correct that polyvinyl chloride (PVC) itself does not contain silica (silicon dioxide). PVC is a synthetic plastic polymer made from the polymerization of vinyl chloride monomers. It is widely used in various applications, including construction materials (like pipes and flooring), medical devices, and packaging.
Silica, on the other hand, is a naturally occurring compound often used as a filler or reinforcing agent in various materials, including rubber and some types of plastics. If you have a specific context or application in mind regarding PVC and silica, please let me know, and I can provide more detailed information!