What are the types of plastic, how to distinguish them, and where to find the logos. 

Historical Overview

The plastic was  first introduced to the public in 1862 by an English scientist Alexander Parkes. The brand was called “Parkesine”, but first, it wasn’t completely made of synthetic materials and was an alternative to ivory and the horns. Even though this material was a novelty, it didn’t achieve much commercial success. 

The plastic we use today, was invented by a German scientist Herman Staudinger in 1920. He discovered the polymers [i] and their various manifestations, for which he was awarded the Nobel prize in 1953. Over time, the polymer mixtures increased, becoming separate types of plastic, and since throwing the plastic to the landfill or burning it is not a solution (it doesn’t burn completely, and while burning, chemicals are emitted to the air), it became necessary to sort and recycle them. The Society of the Plastics Industry (SPI) (currently Plastics Industry Association) brought up a classification system for plastic in 1988: giving a chance to the consumers and the recyclers to differentiate between types of plastic. Producers put the SPI code or number on each plastic product, usually at the bottom.  

The types of plastic, their properties, logos, and everyday use

Let’s get acquainted with  the types of plastic, their properties, and plastic items used in our daily lives below.

  1. Polyethylene terephthalate (PET) is marked with  number 1. Sometimes it absorbs the good or bad smell or the taste of the food or drink that it contains.  Containers or items made of this kind of plastic, are usually recycled.  Polyethylene terephthalate or PET, as it’s known in international terminology, is used in  the manufacture of various household items (such as drinks, medicine bottles,  ropes clothing and carpet fibers). 
The type of plastic General properties Common usage
Polyethylene terephthalate (PET) Waterproof,

heat resistant,

tough,

insoluble

Bottles of mineral water, carbonated drinks and beer,

Solid food packaging,

Soft drinks and water bottles,

Fiber intended for clothes and carpets

Some bottles for shampoo and mouth washing liquids

 

2. The products made of high-density polyethylene (HDP) are marked with number 2. They are usually very safe. No case of emission of chemicals in food or beverage contained in them has been reported yet. The goods and containers made of high-density polyethylene or HDP are usually recyclable. Dairy containers, car oil containers, liquid soap and shampoo bottles, detergent and bleach containers are made of high-density polyethylene. It’s not safe to reuse the containers made of high-density polyethylene for food if it wasn’t intended for food from the beginning.

The type of plastic General properties Common usage
High-density polyethylene Excellent water resistance,

high heat resistance, tough, 

rigid, semi-flexible or solid, 

sometimes soft, waxy surface, 

might let gas inflow, 

 

 in some cases, wrinkles may appear   when touched

the bottles made with pigments also withstand pressure

Bottles for cleaners, whiteners, and bleachers

Snack packagings, transparent plastic packagings for porridge

Bottles for milk and non-carbonated drinks

Toys, buckets, pipes, plastic boxes, 

flower pots

Trash cans

 

3. Polyvinyl chloride (PC) is marked with number 3 and sometimes is recycled. It is used in the production of all types of pipes and tiles, as well as plumbing pipes. 

The type of plastic General properties Common usage
Polyvinyl chloride (PC) Hard and solid (flexible, in case of plasticity), chemical resistant

long-term stability,

stable electrical properties,

gas resistant

Bank cards,

food packagings,

food containers

door and window frames

water pipes and fittings

artificial leather goods

 

4. Low-density polyethylene (LDP) is marked with number 4 and sometimes is recycled too. It is both resistant and flexible. Sticky food packagings, compressible bottles, and grocery bags are made of this.

The type of plastic General properties Common usage
Low-density polyethylene (LDP) Tough, sometimes flexible,

may have a sticky or waxy surface

soft, easily scratched,

low melting point,

stable electrical properties,

high resistance to humidity

Thick bags for shopping  and trash

Packaging tapes

flexible bottles,

irrigation pipes,

some bottle caps

 

  1. Polypropylene (PP) is marked with number 5 and is rarely recycled. PP is hard and is usually able to withstand high temperatures. Kitchen utensils, yogurt containers, etc. are made of this. Plastic bottle caps also are often made of polypropylene. 
The type of plastic General properties Common usage
Polypropylene (PP) Excellent resistance to chemicals,

high melting point,

rigid but flexible

sometimes waxy or sticky surface

semi-transparent

hard

Most of the bottle caps,

Containers of ketchup, yogurt, and syrup

Chips, cookies packagings (or bags)

Plastic boxes, flower-pots, straws

 

Fibers for carpets, tarpaulin and etc.

 

  1. Polystyrene (PS) is marked with number 6 and is usually difficult to process. Food plastic soft containers, plastic tableware, etc. are made of it.
The type of plastic General properties Common usage
Polystyrene (PS) glass-like surface,

hard or with bubbles inside,

tough,

affected by oil or solvents

Egg boxes,

Trays and cups provided at fast food outlets

video cassettes,

disposable utensils,

hangers,

low-quality toys that break easily

 

  1. Number 7 (OTHER) is used for other types of plastic that don’t belong to the six subgroups mentioned above. Polycarbonate and polylactide belong to his group. This kind of plastic is difficult to recycle. Polycarbonate (PC) is usually used to produce discs, bottles for kids and items like this. 
The type of plastic General properties Common usage
Other (OTHER) There are polymers that are widely used especially in engineering. Those are marked by number 7 and the note Other or by a triangle and 7-19 numbers Nylon (PA), acrylonitrile butadiene styrene (ABS),

Polycarbonate (PC)

Striped or multilayer mixed polymers.

 

In the conditions of the increasing quantity of trash and the continuous production of plastic, it is extremely important to know how to sort and recycle the trash.

[i] The polymer is an oil base from which plastic is made. More: https://www.encyclopedia.am/pages.php?bId=1&hId=669


Author: Marine Ohanjanyan © All rights reserved 

Translator: Argishti Yeghyan

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