Influence of Surface Structure on Ball Properties during a Professional Water Polo Game.

The use of modern materials in sports, in terms of chemical composition and surface texture, entails both progress in results and an increasing discrepancy in the technical parameters of the equipment used. This paper aims to demonstrate the differences between balls admitted to a league and world championships in composition, surface texture, and the influence of these parameters on the water polo game. This research compared two new balls produced by top companies producing sports accessories (Kap 7 and Mikasa). To obtain the goal, the measurement of the contact angle, analysis of the material using Fourier-transform infrared spectroscopy, and optical microscopic evaluation were used. The analysis of the surface free energy shows significant differences (Kap 7 32.16 mJ/m 2 , Mikasa 36.48 mJ/m 2 ). In the case of both balls, anisotropies of the structure of the furrows were observed, however, the Mikasa ball is slightly more homogeneous than the Kap 7 ball. The obtained results from the analysis of the contact angle, as well as the composition and real feedback from the players, indicated the need to standardize the material aspect of the regulations so that the sports results are repeatable every time.