The Plastic Bag


Plastic bags were first introduced as sandwich bags since 1957, produce bags since 1969, merchandise bags since 1974 and in grocery stores and check stands since 1977. Recycling plastic bags has been available at supermarkets nationwide since 1992 and there is a growing market for recycled plastic that did not exist a decade ago as recyclers make 15-20 cents per pound of collected bags.

Types of Plastic Bags

Degradable Plastic Bags – Degradable plastic is designed to undergo changes in its chemical structure under specific environmental conditions. It can be broken down by chemical or biological processes. There are 5 different types of degradable polymers:

  1. Biodegradable polymers - A degradable plastic where degradation results from naturally occurring microorganisms, such as bacteria, fungi and algae. Biodegradable bags have limited applications, high costs, and a tendency to tear and break easily.
  2. Compostable polymers - A plastic that undergoes degradation by biological processes during composting. In the proper environment, compostable plastic is completely biodegradable and can be completely consumed in 180 days or less . These bags would work well for simple uses, such as food service, lawn, grocery, department store and pet bag products. However, they would not work well for trash because of the exposure to moist debris.
  3. Oxi-biodegradable polymers – This type of plastic undergoes controlled degradation through additives that can trigger and accelerate the degradation process.
  4. Photodegradable polymers – These bags break down when exposed to ultraviolet (UV) light or UV-sensitive additives.
  5. Water-soluble polymers – Water soluble polymers dissolve in water within a specific temperature range.
High Density Polypropylene (HDPE) Bags – This type of plastic is used to make unbranded ‘singlet’ bags that are commonly used in supermarkets, service stations and food outlets. HDPE is manufactured from ethylene and is a by-product of gas or oil refining. These types of bags are fully recyclable but do not biodegrade.

Low Density Polypropylene (LDPE) – These are generally branded and used as ‘botique’ bags at stores selling higher value goods at department stores. LDPE is also manufactured from ethylene and is a by-product of gas or oil refining. Like HDPE, LDPE does not biodegrade. There are no recycling programs in King County for LDPE bags.

Non-woven Polypropylene – This type of plastic is used to make ‘reusable’ bags. There is currently no recycling market for polypropylene bags at end-of-life due to their relatively low volume in King County. Non-woven polypropylene is also non-biodegradable.


Evaluation of Performance of Rigid Plastic Packaging
California State University and the Chico Research Foundation produced this 2007 research report which evaluates the compostability of plastic products. The study determined that compostable plastic materials perform well in a variety of different applications and can reduce the amount of space in landfills.

California Film Extruders and Converters Association (CFECA) Newsletters
The California Film Extruders and Converters Association (CFECA) is a trade association of California based manufacturers and suppliers that impartially represent the interests of the plastic film extruding and converting industry. The organization issues a monthly newsletter that addresses topics such as the effect of plastic legislation, types of plastic polymers, plastic bags in foreign countries, recycling programs and the life cycle of the plastic bag.