In daily life, people have exposed more plastic bags (membranes), generally PVC (PVC) and polyethylene (PE) plastic film (bag), how to distinguish them, the following summarize several simple methods :  
 
1, touch method:  
 
Touching a lubrication with a hand, the surface is like a layer of wax (chemically referred to as a wax feel), which is a non-toxic polyethylene film, and the polyvinyl chloride film is touched.  
 
2, jitter method:  
 
The sound is jitter, the sound is brittle, and the quality is easy to float is a polyethylene film bag. The use of hand shake sound is a polyvinyl chloride film bag.  
 
3, combustion method:  
 
In the case of flammable, the flame is yellow, there is a paraffin oil drop in the burning, and the gas when the candle is burned, and is a non-toxic polyethylene film bag. If it is not easy to burn, it is extinguished from fire, the flame is green, which is a polyvinyl chloride film.  
 
4, immersion method:  
 
The plastic bag is immersed in water, and after pressing the water by hand, it can float the surface of the water surface as polyethylene, and the sinking of the water bottom is polyvinyl chloride (the density of polyethylene is less than water, the density of polyvinyl chloride is greater than the water; at normal temperature, respectively 0.92 g / cm3 and 1.4g / cm3).  
 
In addition, the copper wire can be used, and the copper wire is burnned in the fire, then the copper wire is contacted with the test plastic film, producing chemical changes, and then re-placing the copper wire with the plastic ingredient back to the flame. At this time, you need to observe carefully. If there is a colorful, dazzling green flame, this plastic material contains chlorine element, which belongs to the polyvinyl chloride material.