Types of Plastics
There are 7 different types of plastics with different properties. They are identified by resin identification codes 1-7. If you've ever looked on the bottom of a plastic product, you will see a number 1-7 inside of the recycling symbol, as shown in Figure 1. The letters beneath them are abbreviations of the names of the different types of plastics.
Plastic code #1 is PETE or PET, which stands for polyethylene terephthalate. Plastic code #2 is HDPE, which stands for high density polyethylene. Plastic code #3 is V or PVC, which is for polyvinyl chloride. Plastic code #4 is LDPE - low density polyethylene. Plastic code #5 is PP, or polypropylene. Plastic code #6 is PS, which stands for polystyrene. Plastic #7 is any other plastic that is made of combinations of the other six types of resins. These 7 types of plastics are categorized into 2 groups. The first group, containing codes 1 and 2, are the resins that most municipal programs accept. The second group, containing all the other codes (3-7), are the resins that have a very low rate of recyclability, meaning that very few municipal waste programs accept them.
How Different Plastics are Used
- Code #1 plastics (polyethylene terephthalates) can be used in plastic bottles for things such as soft drinks and water, in food jars for things such as peanut butter and jelly, in microwavable food trays, packaging, and in textiles.
- Code #2 plastics (high density polyethylenes) can be used in bottles for things such as milk and shampoo, in plastic grocery bags, cereal box liners, shipping containers, injection molding, pipes/conduits, and in wire coverings.
- Code #3 plastics (polyvinyl chlorides) can be used in rigid packages such as blister packs and clam shell packages, in flexible packages such as plastic wrap and meat wrap, PVC pipes, window frames, fencing/decking/railing, medical tubing, cable insulation, and carpet backing.
- Code #4 plastics (low density polyethylenes) can be used in garbage bags, plastic wrap, coatings for cardboard milk cartons, beverage cups, container lids, various plastic toys, ketchup bottles, injection molding, adhesives and sealants, and cable coverings.
- Code #5 plastics (polypropylenes) can be used in yogurt containers, medicine bottles, plastic bottle caps, ketchup bottles, fibers, and carpeting.
- Code #6 plastics (polystyrenes) can be used in plastic cutlery, rigid food containers, protective foam packaging, packing peanuts, compact disc cases, medicine bottles, cable spools, cassette cartridges, coat hangers, medical products, toys, building insulation, and electronic housings.
- Code #7 plastics (others) can be found in large water containers, some juice and ketchup bottles, oven baking bags, and custom packaging.
The five most dangerous resin codes to burn are resin codes #3-7. These are also the types of plastics that most municipal waste programs do not accept. This means that not only are they the most dangerous, they are also the most likely to be backyard burned. These plastics are plastics PVC, LDPE, PP, PS, and combinations of those three. The burning of any plastic releases pollutants into our environment. The most dangerous of these pollutants are dioxins and other persistent organic pollutants.
How to Identify Different Resin Codes
To find out which resin code/plastic type a plastic is, look on the bottom of the plastic item. Resin codes are usually found here. The resin codes look like a number with a recycling symbol surrounding it, as shown in Figure 1. If there is no symbol, you can assume that the plastic is resin code 7.