Do You Know Plastic Recycling Symbols Mean? (Part 1)

- Jul 21, 2020-

Do You Know Plastic Recycling Symbols Mean?

Plastic is a widely used material, but also professional materials. No matter industrial design or mechanical design, plastic products can be seen everywhere in our daily life. Next, I will introduce the common plastic material numbers and their characteristics for you.


In today's highly informed age, most housewives are aware of the number 5 plastic used in microwave ovens, and many of them subconsciously pick out a triangle when they get a plastic container and carefully identify the number. But not many people really know these numbers, which raises a lot of questions. For example, is plastic number 5 the safest? So in order to make better use of plastic numbers to improve the quality of life, the first thing we should do is figuring out what the plastic numbers mean.


The triangle on the plastic container is a sign of recycling actually. Numbers is the mark of the entry into the channels of different recycling. In other words, when recovery specialist saw the plastic bottles on the no. 1, knew that should be recycled by means of channel 1. What’s more,  numerical magnitudes has nothing to do with the nature of the bottle itself


There are about 140 commercially available plastics, about 30 are used daily. But there are only seven types of plastic that are large enough to be recycled in the same direction, that’s why there are only seven numbers in the triangle: 1-7. Each number corresponds to a different plastic variety, it’s PETE, HDPE, PVC, LDPE, PP, PS, PC in turn. Each abbreviation has a "P" in it, which means "Poly-" in English.


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Symbol 1: PET (polyethylene terephthalate)


Soft and transparent bottles or cans are almost made of PET, it’s beautiful and generous, with a low price.


No. 1 plastic PET, the scientific name of polyethylene terephthalate, also referred to as polyester plastic. It’s common in life, the current beverage bottles and food oil bottles are almost all used this plastic. If the molecular weight of the PET is large enough, it can be used in the fiber industry.


PET is characterized by high transparency, water-resistance, and oil resistance, but it is not very heat-resistant. Many people are aware of this phenomenon, that when you use a normal mineral water bottle to receive hot water from a water fountain, the bottle begins to be deformed, and the temperature is about 85 degrees.

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Symbol 2: HDPE (high-density polyethylene)


Opaque and hard bottles or cans are made of HDPE, it has strong endurance and widely used in the daily product container.


Plastic No. 2, HDPE, or high-density polyethylene, is the easiest to find in your bathroom as a chemical container and is also used in many large beverage bottles.


Different from PET, HDPE is highly crystalline, so it appears opaque and harder, even a little brittle. Because of its high strength, fall resistant and impervious to light, daily products often use plastic No. 2.


Similar to PET, No. 2 plastic is not very heat-resistant, it’s a little bit stronger than PET, however, it deforms easily after 100 degrees Celsius.

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Symbol 3: PVC (polyvinyl chloride)


Plastic No. 3, PVC, also known as polyvinyl chloride, is the only one of the seven plastics not recommended for contact with food because it contains chlorine. In fact, the chlorine in the material is not easily dissociated under normal conditions of use, although No. 3 plastic is rarely seen in food containers. PVC is also the only one of the seven plastics that must use plasticizer, which allows it to change its state from soft and elastic to hard and brittle.


Since PVC can present a soft and elastic side, it can simulate some USES of rubber or leather, such as artificial leather, which is widely used in the interior of Japanese cars, disposable inspection gloves, floors, tablecloths, plastic shoes. Besides PVC prices are much lower than natural rubber and polyurethane artificial leather.

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Symbol 4: LDPE (low-density polyethylene)


LDPE is not good at keeping fresh, but it is still one of the most ideal materials for plastic wrap


Plastic No. 4 HDPE and plastic No. 2 are brothers, technically called low-density polyethylene.


But essentially 2 and 4 have different structures, except that the monomers are all ethylene.


HDPE's transparency is relatively high, so we can mainly see it in plastic wrap, plastic bags, and other aspects of our daily life.

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