How to Distinguishing PVC from PET

Some customers who are new to PVC and PET might not be able to distinguish them quickly because they look alike, especially PVC with natural color and transparent PET. Here are the methods to judge PVC and PET.

1. Distinguishing by appearance

First of all, section or cross section can provide clue for PVC and PET identification. PVC section is usually blue since it contains ultramarine, disperse violet, phosphor and some other colorant. The material whose section is not blue is PET. On the other hand, lines of material also indicates something. For example, PVC is normally calendered so that it has flow patterns on its surface. However, these two methods both have limits in that PVC can be made to its natural color, which approaches the color of PET. Besides, PVC can also be made by extrusion without causing any flow pattern. In this case, the following other two methods can be used when this means is not useful.

2. Distinguishing by folding

Snip a piece of material of PVC and PET and fold them. We can find that the crimp of PVC looks white. The reason is the special molecular composition and the production technique of PVC sheet. Generally, the sheet having white crimp can be given as PVC and that with unclear or unobservable white crimp is PET. However, this method is also insufficient when the formula for production of PVC changes and makes the crimp no longer clear. For instance, changing some ingredients of PVC can reduce white of the crimp. Therefore, we still need another auxiliary method.

3. Distinguishing by burning

This method is developed on the basis of the first method. We can differentiate these two materials by burning them. Snip a piece of material and burn it. Black smoke, extinguishing as the lighter extinguishes, strong kick and black crystal at the edge are all signals for PVC. PVC is polychloride molecular and is combustion-supporting. It can extinguish when it is moved away from fire. On the other hand, PET is polyester and is degradable and flammable. The burning PET is smokeless and can keep burning when the fire is moved away. Its burning edge is pretty smooth and generates little crystal.