What Does Phenolic Resin (PF) Mean?
Phenolic resin, also known as phenolic formaldehyde resin (PF), is a synthetic resin produced from the polymerization of a phenol (C6H5OH) and a formaldehyde (CH2C=O). The polymer consists of repeating units of –[(C6H3OH)-CH2]- with methylene (-CH2-) linkages bridging carbon positions ortho to the phenolic hydroxide group (-OH).
There are two types of phenolic resins, phenolic novolac resins and phenolic resol resins, depending on the conditions used to create the polymer. Phenolic novolac resins are further modified with a cross-linker for them to harden. Both types are known for high chemical and water stability and temperature stability above 300°C (572°F).
Corrosionpedia Explains Phenolic Resin (PF)
Phenolic resol resins are prepared in conditions with the formaldehyde to phenol ratio being greater than 1 (typically 1.5). The reaction is catalyzed by a base to create a reactive phenoxide (C6H5O-) group, which reacts with the formaldehyde to create hydroxylmethyl phenol units. Thermosetting at 120°C
(248°F) initiates crosslinking, which creates a highly networked
polymeric structure with good thermal stability, hardness and chemical
Phenolic novolac resins are prepared when the formaldehyde to phenol ratio is less than 1 under acidic catalytic conditions. The molecular weights of the produced intermediate polymers are in the low thousands, with only 10-20 repeating units. In order to gain the strong properties of PF resins, the material is thermoset with a cross-linker such as hexamethylenetetramine. Phenolic resins typically range from yellow to dark-red.
Due to its great hardness, PF resins are often used to produce products such as billiard balls, chemically resistant countertops, circuit boards and other panels. In other cases, PF resins are useful for laminations and as a binding agent for parts such as brake pads. They often find applications as coatings and adhesives.