VARIATIONS OF THE THEME OF PHENOLICS

It may be assumed that even those with some knowledge of the many plastics may assume that the phenolic resins are concocted from formaldehyde and phenol, along with a catalyst.

The above is a fraction of the story. The possible phenolics may include three isomers of cresol, six isomers of xylenol and other similar aromatics. These may occur in various combinations and proportions. These may react with formaldehyde or other aldehydes, in mol ratios of less than 1.0 to as much as 4.0 aldehyde/phenol. Any of these mixtures may be reacted with acids or alkalines, the former with ratios less than 1.0 and the latter with ratios above. The acids may be any which can easily be contained in the reaction vessel. And the alkaline catalyst may be ammonium hydroxide, sodium hydroxide or carbonate, barium hydroxide, morpholine or any other suitable catalyst which will promote pH of more than 7.0. The above possible combinations are nearly without limit.

Any of these resins may be modified to make a resin solution which may be used to impregnate webs of various materials: cotton fabric, paper, fiberglass fabric and most synthetic fabrics. Or the resins may be combined with fillers as reinforcements such as wood flour, cotton flock, or rags, fiberglass fibers, mica, serpentine dust, and so forth. These materials may be used to make laminar products, molded products of an infinite range of colors and properties. The laminar type products may be convolutely-wound tubing of any convex cross section, or processed so that the laminations lie at any desired position to best suit a function.

And to confound those who think that "Bakelite" must be brown or black, it is possible to produce a molded phenolic without reinforcement. Such a transparent phenolic resin was marketed prior to 1942 and used in parts for automatic milking machines which allowed the molded pieces to be sterilized.

For more information, contact G. Marshall Naul, American Plastics History Association, 209 Glen St., Chestertown, MD 216210-1417, 410-810-1758.