The term "phenolic" is used to refer to a few different substances made with phenol, an organic compound. It can describe a type of resin used to create various consumer items and is the name given to a class of plant-based chemical compounds. It can also refer to carbolic acid, an organic material that has been used in various medical and cleaning products.
Phenolic resin is made by combining phenol and an aldehyde. When these organic compounds are mixed, and both pressure and heat are applied, it causes polymerization, which is a chemical reaction that can be used to mold solids. Since it is both versatile and durable, this resin is used to make a wide variety of consumer and industrial products.
A range of goods, from billiard balls to kitchen gadgets, and automotive parts to construction adhesives, are made with phenolic resins. The material is often used to create consumer fittings, such as the plugs on electronic devices, handles for pots and pans, and screw-tops on most bottles. Its affordability and the ease with which it is molded can make it an ideal choice for many applications.
Resin may be made by mixing simple phenol with any number of aldehydes, but the combination made with formaldehyde — known as phenolic formaldehyde resin (PF) — is the most widely used. It was the first synthesized resin, and was marketed under the brand name Bakelite®. Soon after, because it was cheap to make and admired for its beauty, this substance was used to make many household objects, including jewelry, radios, musical instrument components, and cameras. While the heyday of items made with it was from 1920 to 1940, this malleable material is still used to make board game pieces, gun parts, and even heat shields on rockets.
Use as a Binder and Insulator
The combination of phenol and formaldehyde is also frequently used as an agent to bind together composite woods, including chipboard and plywood. While it can be somewhat brittle when used in this way, it produces very little smoke if it catches on fire, and, at high grades, can resist temperatures up to 370°F (185°C). In construction, phenolic foam made from these compounds is often used as insulation, usually in the form of rigid sheets. This type of insulation is often chosen for its ease of installation, affordability, and thermal mass — it's ability to moderate temperature fluctuations.
As a Laminate
Sheets of paper, glass fabric, and certain kinds of cloth, like linen and cotton, can be treated with phenolic resin, then pressed and heated to form hard, laminated plastic sheets. This composite laminate is heat-resistant, strong, and waterproof. The flat plates are easily shaped or carved and frequently used on tables, counter tops, and even as pick guards on guitars.
Phenols in Organic Chemistry
Any member within the class of organic phenols may be termed a phenolic compound. Compounds in this class are simple hydrocarbon groups, similar to alcohols. Phenolics are varied and found in a range of natural things — from capsaicin, the heat agent in chili peppers, to neurotransmitters in the brain, like dopamine.
Natural Compounds in Plant Antioxidants
Phenols are found in many plants, including fruits and vegetables. While the study of these substances is ongoing, it is known that their antioxidant properties — found in wine, berries, and many types of tea — may protect cells from damage and death. These substances are also found in other foods, such as olive oil, and in certain dietary nutrients, like vitamin E.
Carbolic acid is another name for phenol or phenic acid, and is a natural substance that is solid, white, and crystalline. It was originally derived from coal tar, and has been used in soaps, cosmetics, and cleaning agents. Through the 19th and part of the 20th centuries, this mild acid was used medicinally, particularly as an antiseptic and topical anesthetic in and around the mouth. It is toxic, however, and can cause chemical burns to the skin, so its use has been largely discontinued in favor of safer alternatives.