The specific gravity of PVC is 1.38.
The specific gravity of PP is 0.92 (1.0 for colored PP).
The specific gravity of PS is 1.04.
By observing the appearance of plastics, we can initially identify the main categories of plastic products: thermoplastics, thermosetting plastics or elastomers. Generally speaking, there are two types of thermoplastics: crystalline and amorphous. The appearance of crystalline plastics is translucent, opaque or opaque, and it is transparent only in the film state, with hardness ranging from soft to horny. Amorphous rubber is generally colorless, completely transparent without additives, and its hardness ranges from hard to horny rubber (plasticizers and other additives are often added at this time). Thermosetting plastics usually contain fillers and are opaque. If they do not contain fillers, they are transparent. Elastomer has the feeling of rubber and a certain stretching rate.