Pvc, as it degrades, forms conjugated double bounds that eventually work their way from the infra red into the visible spectrum. So... Can an NVDI camera detect or other near infrared camera detect pvc microparticles?
I checked youtube. There are videos of cameras separating all kinds of plastics with NIR. That is PE , PS, PVC, and a bunch of others. So the approach is viable. Whether it will work with the ndvi cameras is another question.