Shellac chemical composition

In many cases, natural resins such as copal resins, amber, shellac, and colo-phonium, which were most widespread in the early period of plastics, differ widely in terms of their properties and chemical composition depending on their origins and production methods. Consequently, it is extremely difficult or even impossible to identify these materials by simple techniques. Instead, it would be advisable to conduct several laboratory tests. In the following, a few hints are given for a brief introduction. More detailed investigations may be based on the works of Thinius and Hummel, which mostly involve a higher test complexity. 

A method for determining the chemical composition of natural resin shellac was developed based on reactive pyrolysis-gas chromatography(Py-GC) in the presence of an organic alkali, tetramethylammonium hydroxide(TMAH). Py-GC using 25% TMAH aqueous... 

Natural resins are generally described as solid or semisolid amorphous, fusible, organic substances that are formed in plant secretions. They are usually transparent or translucent yeUow-to-brown colored, and are soluble in organic solvents but not in water. The principal uses for natural resins are in varnishes, printing inks, adhesives, paper size, and polymer compositions. The term natural resins includes tree and plant exudates, fossil resins, mined resins, and shellac. They often have been altered from their original state during isolation and processing. For some appHcations, the resins have been chemically modified to increase their industrial utiUty. 

When this is done it is seen that in all cases plastics materials, before compounding with additives, consist of a mass of very large molecules. In the case of a few naturally occurring materials, such as bitumen, shellac and amber, the compositions are heterogeneous and complex but in all other cases the plastics materials belong to a chemical family referred to as high polymers. 

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