There are two kinds of common plastics: one is a polyethylene film; the other is a polyvinyl chloride film. The plastic bag made of polyethylene film is non-toxic and can be used to hold food, but the strength is poor, and can not withstand 80 The temperature above °C, and a certain degree of gas permeability, should not be used for long-term use of tea, spices and so on. Plastic bags made of polyvinyl chloride film are toxic and therefore should not be in direct contact with food. Polyvinyl chloride plastics are commonly used in raincoats, soles, bedspreads, curtains, tablecloths, handbags, and the like.
An easy way to identify the above plastic bags:
1. Touch method: It feels lubricated by hand, and the surface is coated with a layer of wax (chemically called waxy), which is a non-toxic polyethylene film; and the polyvinyl chloride film is somewhat sticky to the touch.
2, the dithering method: the hand-shake sound is brittle, is a non-toxic polyethylene film; the hand-shake sound is low, it is a polyvinyl chloride film plastic bag. 3, burning method: fire in the fire, the flame is yellow, burning paraffin-like oil drops dripping. And the smell of the candle burning, is a non-toxic polyethylene film; if it is not easy to burn, it will be extinguished from the fire, the flame Green plastic bag with PVC film.
4. Immersion method: a plastic bag that is immersed in water and pressed into the water by hand to float out of the water is a non-toxic polyethylene film; the sinking into the bottom is a polyvinyl chloride film plastic bag. Polyethylene English, referred to as PE, is a polymer of ethylene, non-toxic. Easy to color, good chemical stability, cold resistance, radiation resistance, electrical insulation. It is suitable for packaging materials for food and medicine, making utensils, medical equipment, and insulating materials for the electronics industry.
Polyvinyl chloride, abbreviated as PVC, is a polymer of vinyl chloride. It has good chemical stability and is resistant to acid, alkali and some chemicals. It is resistant to moisture, ageing and flame retardant. It should not exceed 60 ° C when used and will harden at low temperatures. Polyvinyl chloride is divided into soft plastic and hard plastic. The soft type is mainly made into a film, which is used as a packaging material, a rainproof article, an agricultural seedling film, etc., and can also be used as an insulating layer of a cable or a wire, and an artificial leather product. Rigid, generally made of tubing and sheeting, used as a water pipe and transporting corrosion resistant fluid pipes, which are used as linings and floors for various tanks.