Fenoliformaldehydi

Fenoliformaldehidi, also known as phenol-formaldehyde resin, is a synthetic thermosetting polymer produced by the condensation of phenol with formaldehyde. It forms a highly crosslinked network on curing, providing heat resistance, dimensional stability, and good electrical insulation. It is one of the oldest synthetic resins and underpins many modern thermosetting systems.

There are two principal types: novolac and resol. Novolac resins form under acidic conditions with a limited degree of condensation; they are soluble and require a curing agent, such as hexamethylenetetramine, to complete crosslinking. Resol resins are produced under basic or neutral conditions with excess formaldehyde and cure upon heating, releasing water and forming a network without added hardeners. The chemistry yields methylene and ether bridges between phenyl rings.

History and usage: Baekeland’s work in the early 20th century led to Bakelite, the first widely used phenol-formaldehyde resin. Phenol-formaldehyde resins have been used for electrical insulators, molded parts such as knobs and radio cabinets, decorative laminates (for example, phenolic laminates used in some countertops and backplanes), and as adhesives in wood composites.

Properties and limitations: PF resins are rigid, with high heat and chemical resistance and excellent electrical insulation, but they can be brittle and are relatively difficult to recycle. Residual formaldehyde can be emitted from some formulations, so modern resins are designed to minimize emissions and optimize curing.

Environmental and safety notes: Production and use require ventilation and handling practices to limit formaldehyde exposure. Disposal considerations apply due to the crosslinked nature of cured material and potential residual monomer.