Chemistry of Everyday Things

Recycling PET plastics and Polyethylene Plastic Bags

(Student Activity #9, Appendix D)

Recycling success is dependent upon three factors, whether the product can be recycled into useful new products, if there is an economic market for the products, if it is economically feasible, and if people are willing to recycle them. As noted before, about 24 % of PET bottles are currently recycled. ³ Only 2 % of plastic bags are recycled in the United States. ⁴ One of the problems with plastic bag recycling is that each bag contains very little plastic, so the recycling value for each bag is very low. It is only with a large quantity that economic recovery is realized. In fact, most plastic bag recycling for the west coast of the United States goes to China. This actually works out pretty well, since the empty ships returning to China from delivering exports to the United States take the bags back to China to recycle them, mostly into fibers which China needs. Actually, plastic bags can be more of a problem than a benefit to many recycling centers. In San Francisco, the bags kept tangling the machines used to process recycled plastic, requiring nearly $ 700,000 annually. ^{1 0} Most recycling pickups won't take the plastic bags with the other recycled material. In Delaware, recycling is done in single stream pickups or drop off containers, (recycled materials don't need to be sorted); however, the bags are excluded from the pickups or collection points. Delaware, New York City, and Rhode Island, among others, have laws, though, requiring stores that distribute plastic bags to provide recycling receptacles. ^{1 0} Due largely to the low percentage of recycled bags and the low amount of plastic from each bag, the options for products from recycled bags is largely limited to fibers for clothing or carpet. ^{1 0} There are few incentives for companies to expand the recycled products, since the recycling rate is so low.

Plastic, PET, bottles are recycled at a rate better than any other plastic material. ⁶ Due to the strong cross-linking bonds in the plastic polymers, it is difficult for the plastic in the bottle to decompose. While most recycling centers use density or various photo imaging processes to separate the bottles from other plastics, there are errors and plants have to rely on a relatively large labor costs to manually finish the sorting process. In order to recycle the bottles, they need to be separated from other types of plastic, because the different plastics don't mix together, (like oil and water). Bottles without colors are generally preferred, since the color can't be removed from the original product in the recycling. ⁶ The bottles are melted, washed, and cut into small pellets of material that can be processed into various products, such as: scouring pads, auto parts, tires, paint brushes, landfill liners, paints, fabrics, and synthetic wood products. ^{1 6} In some areas that are offering single stream recycling, such as Delaware, the comingling of the bottles with other materials often renders the bottles unsuitable for some recycling, such as into new water bottles. In fact, recyclers would like to add old recycled PET bottles into new plastic bottles. This would reduce the amount of plastic required for the new bottle, but they have not been able to do that, yet. ^{1 0}