What is Plastic?
Plastics. From popular culture (“There’s a great future in plastics” from The Graduate), to seat belts, to drive through restaurant windows, plastics have been an intrinsic part of our lives for decades. But ask people on the street—“What are plastics?”—and you’ll get an wide range of vague and often contradictory answers.
A modern innovation, plastics have been making products work better for little more than a century. World War II created soaring demand for plastics to replace scarce traditional materials, and the consumer boom of the 50s and 60s cemented plastics’ role in the economy and our everyday lives.
So how are they made, and what are they made from? Let’s find out what these modern materials are all about…
Basis of Plastics
The basics are straightforward. Think back to high school science lessons about atoms and molecules (groups of atoms). Plastics are chains of certain molecules linked together. These chains are known as polymers, which is why many plastics begin with “poly,” such as polyethylene, polystyrene and polypropylene. For example, the plastic polyethylene is simply molecules of ethylene strung together, like beads on a necklace. Polymers can be very simple, made of only molecules of carbon and hydrogen, and sometimes they also have molecules such as oxygen, nitrogen, sulfur, chlorine, fluorine, phosphorous, or silicon. The term “plastics” encompasses all these various polymers.
Sources of plastics (feedstocks)
The raw materials for plastics (often called feedstocks) come from many places, including plants. Some plastics even use salt as a raw material. But most of today’s plastics are made from the hydrocarbons that are readily available in natural gas, oil, and coal. A growing amount of plastics are made from plant feedstocks, such as sugar cane or corn (see bioplastics below). The choice of feedstocks is driven by numerous factors, including efficiency, quality, availability, and environmental factors. In the United States, approximately 70 percent of plastics are made from North American natural gas, a resource with growing domestic reserves. » learn more about the lifecycle of plastics
How are plastics made?
Plastics begin their lives in a refinery or chemical facility as feedstocks that are processed into polymers. Many polymers are then shaped into small pellets that can be shipped all over the country to be made into plastic consumer products, including packaging.
It’s a sizeable enterprise—the U.S. plastics industry employs approximately one million workers and contributes $375 billion to the economy.
Many of the companies that produce feedstocks and plastics belong to Responsible Care®, the chemical industry’s performance initiative on safe, responsible and sustainable management of their products (every American Chemistry Council member company belongs to Responsible Care). » learn more on how plastics are made and where they are used, including packaging
A growing amount of plastics is made from feedstocks that are grown, such as sugar cane or corn. In fact, the first plastics including cellophane were made from bio-based materials—these plastics were largely eclipsed by more efficient plastics. Bioplastics are reemerging today as scientists develop more efficient ways to produce them, as well as in response to concern over the use of finite resources, primarily natural gas and oil. Although bioplastics represent an important area of innovation, attention should be paid to their sustainability considerations (environmental, economic and social), such as water use, recyclability, the effects of farming, greenhouse gas emissions, food supply, and the cost of food.
And there are common misconceptions regarding bioplastics. Many people believe—incorrectly—that all bioplastics are biodegradable; however, the use of plant feedstocks does not necessarily lead to biodegradable plastics. For example, PET plastic made from plant feedstocks has the same chemical formula as PET made from natural gas and oil feedstocks. Bio-based PET plastic is not biodegradable, but it is recyclable. The bioplastic PLA, on the other hand, can biodegrade in a commercial composting facility—but it likely will not be accepted in many of today’s recycling programs (current volumes of PLA are too low to efficiently separate and recycle). » learn more about bioplastics and biodegradability/recycling