Effect of gamma radiation on the crack pattern of a styrene-acrylic emulsion dry droplet

Abstract

We present findings on the influence of gamma radiation on the crack pattern of dried drops of an aqueous styrene-acrylic emulsion. An increase in the dose of gamma radiation reduces the number of cracks and expands the edge of the dried droplet. Furthermore, gamma radiation induces a reduction in the branching of the crack pattern and an increase in the frequency of cracks, with a magnitude comparable to the width of the edge of the dried droplet. The results of the infrared analysis indicated that the micelles surrounding the styrene-acrylic copolymer in the emulsion exerted a protective effect, preventing indirect damage caused by radicals formed due to water radiolysis. The results of the zeta potential and particle size measurements demonstrated that gamma radiation caused an increase in the average size of the micelles, a widening of the size distribution, and a redistribution of surface charges. Doses above 100 kGy induce a loss of emulsion stability. The effects of gamma radiation on the crack patterns were interpreted by considering the dynamics of micelle deposition at the edge of the drop during drying and the appearance of mechanical instabilities in the deposit that lead to cracks. The larger micelles produced due to gamma radiation on the emulsion modify the microstructure formation at the edge of the dried drop, thereby alleviating the formation of mechanical stresses that result in the appearance of cracks.