The Distinction between PVC Film, PE Film, PET Film and PP Film

What about the way to distinct between PVC film, PE film, PE film and PP film? 

Normally, we will identify from the surface and the application, different material, different surface and application. Meanwhile, we differentiate from the flame color, the color and the smell of the smoke by burning. 

The burning feature of the materials as below:

 PVC: self-extinguish after removing fire, will be burnt on the fire, and yellow flame, and dark smoke, with acrid smell. PVC will be self-extinguish right after being deviated from fire, and the burnt part shows black. 

PET: remain burning after removing fire, the PET film edge shrink when burning, dark smoke, with sour smell. The burnt part shows white. PE and 

PP: both are flammable, blue flame. PE film is melting and dropping, and with light white smoke. The smoke of PP is much denser than PE, without melting and dropping. Both materials are with burnt candle smell.