Theory:

The resin codes are made to identify the plastics. In \(1988\),  the Society of the Plastics Industry (SPI) helped standardise the plastic materials for easy identification.
Resin codes are used to identify plastics materials they are made of and ways to dispose of them.
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Resin code
 
The three arrows chasing in a triangle-shaped symbol represents the recycle symbol. The number indicates the plastic's material, and the abbreviation refers to the name of the chemical.
 
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Recycle symbol

Resin code number \(1\) - Polyethylene Terephthalate (PETE):
  
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Polyethylene Terephthalate
 
The other name is PET. It is lightweight and can withstand temperatures. The finished products are made into plastic bottles for water, sports drinks, beer, juice, mouthwash, food jars for jelly, jam, peanut butter, pickles, etc. The recycled plastics are made into fibre for carpet, fleece jackets, beverages bottles, comforter fill, and tote bags.
 
Resin code number \(2\)- High-Density Polyethylene (HDPE):
  
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High-density Polyethylene
 
These are long-lasting and can withstand temperatures. These plastics can be recycled. The finished products are bottles for milk, juice, shampoo, detergents, household cleaners etc.
 
Resin code number \(3\) - Polyvinyl Chloride (PVC):
  
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Polyvinyl Chloride

The other name for polyvinyl chloride is vinyl. These have high resistance to grease, oils and chemicals. They are made into pipes, window frames, fencing etc. polyvinyl chloride is single-use plastics.
 
Resin code number \(4\) - Low-density Polyethylene (LDPE):
  
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Low-density Polyethylene

These are safe, flexible and durable plastics. They can be made into squeezable bottles, frozen food bags, toys, newspapers etc. These plastics can be recycled.
 
Resin code number \(5\) - Polypropylene (PP):
 
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Polypropylene

PP is safe to use and are durable, lightweight. These can be made into medicine bottles, cutlery etc. These are recyclable plastics.
 
Resin code number \(6\) - Polystyrene (PS):
  
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Polystyrene

These plastics are cheap and single-use plastics. These are made into disposable cups, plates, spoons, straws, egg cartons etc.
 
Resin code number \(7\) - Other (Acrylic, Nylon, Fiberglass, Miscellaneous):
  
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Plastic cans

These types of plastics differ from other plastics, which fall into groups \(1\) to \(6\). Their properties depend on the resin combination. These are made into three and five-gallon water bottles, bulk food containers etc. Due to different combinations, some can be recycled, and others may not from these group.