Recent developments in esterified fibrous insulants

The structure of cellulose, is of the various types of acetylated cellulose, is described with special reference to she products known us Cotopa 30 and Cotopa 60. The relationship of the structure to properties such as moisture absorption, d.c. resistance and dielectric loss, is discussed. It is shown that Cotopa 30 (acetylated cotton yielding 30% of combined acetic acid on saponification) is a material having all the mechanical properties of cotton coupled with enormously greater d.c. resistance, marked improvement in a.c. properties under moist conditions and considerably greater heat resistance Cotopa 60 (60% combined acetic acid) is remarkable for its low h.f. loss and power factor, particularly under dry conditions, The electrical aspects of some other textile products, including Insuwools, Insusilks, acetylated paper, cellulose triacetate silk, Nylon, Vinyon and glass, are also considered. The Insuwools and Insusilks give low inflammability with high insulation resistance under dry and atmospheric conditions. Acetylated paper possesses better d.c. and a.c. characteristics than ordinary paper and has the advantage that it can be dried more rapidly. Curves giving the moisture regain of cotton and the various types of acetylated cellulose over the complete range of humidities, the d.c. resistance, power factor at various frequencies, and humidities and other relevant data, are presented.