1. The physical properties of the materials used for plastic bottles are different:
Polyethylene terephthalate (PET) is a colorless transparent substance (amorphous) with a certain gloss, or an opaque milky white substance (crystalline type). It is difficult to catch fire and burn, but once it burns, although the flame is away, it can still continue to burn. When burning, it will melt and burst into fragments. The flame is yellow, the edge is early blue, and there are small drops falling, black smoke, and mountains With a slightly sweet, pungent smell. The performance of pure PET is very poor, especially the impact strength and heat resistance, but after the glass fiber reinforced by the cosmetics manufacturer, various properties are greatly improved.
Physical properties of polyethylene (PE): Polyethylene is non-toxic, tasteless and milky white. The density is 0.91～0.96g/cm3 for crystalline plastic. Polyethylene has a certain degree of mechanical strength, but compared with other plastics, its mechanical strength is low and its surface hardness is poor.

2. Different temperature resistance:
Use temperature-weather resistance: polyethylene will age and become brittle under the action of heat, light and oxygen. Generally, the use temperature of high-pressure polyethylene is about 800C, and that of low-pressure polyethylene is about 1000C. Polyethylene is resistant to cold, has good mechanical properties at -600C, and still has a certain degree of flexibility at -700C. The PE bottle is soft and waxy to the touch. Compared with the same plastic, it is lighter in weight, translucent, and the flame is blue when it burns. Common washing products, chemical packaging, such as detergent bottles. The bottom of the bottle is an environmental protection mark of 2.
3. Different water resistance:
Polyethylene has excellent insulation properties. Polyethylene is insoluble in any known solvents at room temperature, and it is resistant to dilute sulfuric acid, dilute nitric acid and other acids of any concentration, as well as alkali and salt solutions of various concentrations. Polyethylene has a high degree of water resistance, and its performance can remain unchanged after long-term exposure to water. The polyethylene of cosmetics manufacturers has poor water vapor permeability, while the permeability of oxygen, carbon dioxide and many organic substances vapor is good.
PET bottles are highly transparent, shiny, and have a crisp sound when knocked on. Commonly used beverage bottles, snack food bottles, and peanut oil bottles; the bottom of the bottle is an environmentally friendly mark.