A bottle is an everyday item that contains liquids like milk, soda, motor oil and shampoo. It can also store dry products like medicines and nutritional supplements. Bottles are made from a variety of materials and manufactured through multiple processes that can include reheat and blow molding, extrusion blow molding and reciprocating blow molding. Bottles are often made of glass or plastic.
The majority of today’s plastic beverage bottles are made from polyethylene terephthalate (PET), a resin whose chemical ID number is 1. The bottle material is derived from petroleum, which is extracted by drilling or other large-scale extraction techniques in 32 states and many coastal waters in the United States. The crude oil is then shipped to a refinery where the hydrocarbon chains are separated into various fractions.
Refined petroleum is mixed with ethylene and terephthalic acid, which are the raw materials for PET bottle production. This is known as polymerization and results in long molecular chains that can be molded into a wide variety of shapes. PET bottles are commonly used to hold soft drinks and water but they can also contain juices, sports drinks, beer and vinegar.
In the past, glass was the preferred container for bottled beverages but since the early 20th century, plastics have replaced it. Bottled water is the most popular commercial drink sold in the US. In fact, a typical bottle of bottled water has over 10 times the carbonate content of a glass soda bottle and is twice as heavy. The popularity of bottled water has driven the development of plastic bottle technology to keep pace with demand.
The most common plastic bottle is HDPE, a resin with a resin ID number of 2. It is derived from petroleum and has the density-to-strength ratio needed to withstand the pressure of carbonated beverages. It is also used for non-carbonated beverages and other packaging such as bags and piping.
HDPE is recycled at the same rate as plastic #1 bottles and it can be reused for other products such as food and liquid containers or fabricated into pipes and lumber. However, it is not as strong as PET or glass and does not have the same barrier properties against oxygen that other bottle materials do.
Despite the high recycling rates for HDPE, millions of tons of plastic waste still end up in landfills and polluting our land and oceans. Plastic bottle manufacturers and their big brand customers are hoping to change this status quo by using renewable raw materials for plastics.
One such company is Origin Materials, which hopes to make competitively priced FDCA (a monomer that makes up the majority of PET) from lignocellulosic feedstocks such as sugar or cornstarch. The firm has an FDCA pilot plant and is working with BASF to develop an industrial-scale process. The companies are hoping to build a reference plant in Europe that will be used by other plastic bottle makers to test the new material.