From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Extract from the Electrical Review discussing the manufacture and composition of phenol-formaldehyde (bakelite) mouldings.
| Identifier | ExFiles\Box 61\1\ scan0125 | |
| Date | 12th September 1930 | |
| X6011. Extract from Electrical Review dated Sept. 12th 1930. MOULDED INSULATION. A few of the insulating properties of the phenol formaldehyde class of mouldings, commonly known as "bakelite", with special reference to their behaviour at high temperatures and as insulators for conductors carrying radio-frequency currents. by LESLIE M.T. BELL. -------------------------- The Manufacture and Composition of Phenol-formaldehyde Mouldings. The mouldings consist essentially of an almost homogeneous mixture of wood flour and synthetic resin, but, to assist the moulder and supply the demands of the public, the manufacturer adds to the mixture small quantities of colouring matter (dyes or pigments); fluxes, usually waxes; and "accelerators", hexa or alkaline earth compounds. A typical mixture would be as follows :- Synthetic resin ............................ 40% Dried wood flour (90 m.{Mr Moon / Mr Moore}) .................. 50% Brown pigment (iron oxides) ................ 7.5% Montan wax ................................. 2% Lime and magnesia .......................... 0.5% The synthetic resin itself is interesting; it consists of a compound formed by the direct union of members of the phenol family with formaldehyde, the action being promoted by the use of a catalyst, such as hexamethylene-tetramine, lime, or soda, a typical formula being :- Phenol ice crystals ........................ 50 lb. 40% formaldehyde ........................... 40 lb. Hexamethylenetramine ....................... 0.2 lb. It will be seen at once that the first effect of the resin formation will be the liberation of the water in which the formaldehyde is dissolved. In addition to that water a small quantity of water is liberated from the uniting chemicals themselves. Every effort is made by the manufacturer to remove all the water, but a quantity of it defies his efforts | ||