A bottle is a container for holding liquids. It has a narrow neck, usually with a cap for sealing the contents. It can be made of glass or plastic. Bottles are used to hold beverages, such as water or milk, and some other liquids, such as vinegar or alcohol. They can also be used to store food, such as jams and canned vegetables.
A new plastic material is gaining ground in the bottle market: polyethylene furan, or PEF. It is a thermoplastic derived from petroleum hydrocarbons by reacting ethylene glycol with terephthalic acid. This produces a polymer with long molecular chains, which can be shaped into bottles. This type of bottle has the potential to replace PET, but it still needs to be tested under real-world conditions.
PET plastic is currently the most popular material for making bottles. It is produced by injection and extrusion blow molding. During injection molding, pellets of PET are melted and injected into multiple-cavity molds. The plastic cools and hardens to form the bottle’s shape, and the mold is then closed to make the threaded neck opening. The resulting parts, called parisons, are shipped to bottling facilities where they are capped and filled with liquids to produce finished bottles.
Another type of plastic used to make bottles is polypropylene. This is a crystalline and rigid thermoplastic, which comes from the monomer propane or propylene. It is found in medical devices, equipment and packaging trays, but it is most well-known as the material that makes plastic water bottles. It is more durable than PET, with stronger properties and resistance to chemicals, such as acids and salt solutions. It is able to be molded into various shapes and is FDA approved for direct contact with foods.
The most common way to make a glass bottle is by cooling molten ingredients quickly. This creates an inorganic, solid material that is clear and translucent with a high gloss. It can be shaped into a variety of containers and is resistant to the action of natural elements, although it is fragile and cannot be shaped as easily as other types of plastic. Bottles of this type are often sold as one-time-use items, but returnable versions have become more popular due to environmental concerns.
Once discarded, bottles can take hundreds of years to break down into microplastics, which drift with ocean currents until they meet one of the large systems of rotating currents known as an oceanic gyre. These gyres are full of debris from the ocean surface and the human environment, including single-use plastics like bottles.