Physical structure of phenolaniline–formaldehyde resol resin and its kaolin–filled phenoplasts

Abstract

AbstractAn investigation of the physical structure of samples of phenoaniline–formaldehyde resol resin in uncured and cured state, and of its phenoplasts containing different ratios of kaolin filler, was made with the aid of electron microscope pictures. The uncured and cured resin consists of microglobules of a size of 40–80 Å, which agglomerate to form larger‐sized globules of various dimensions. After a mathematical elaboration of the results of a large number of measurements, it was established that the diameters of the globules are casual values distributed in accordance with the normal (Gaussian) law. Both in the resin and in the kaolin‐filled phenoplasts (at a rate of 25 to 47 vol‐%), after curing at 170–180°C and a pressure of 300 kg/sq cm, the mean diameter of the observed globules was of a rather steady value and remained within the limits of 230–240 Å (with a standard deviation of 30–40 Å). A method was elaborated of determining the mean thickness of the adsorption coating of the resin on the filler particles. Calculations show that in the filling interval we have chosen, the thickness of the absorption coating is not below 1.8–0.6 times the mean thickness of the globules.