Influence of Nano Titanium Dioxide Coating on the Dust Accumulation Behavior of Polymethyl Methacrylate

Polymethyl methacrylate (PMMA) has the advantages of excellent transmittance, light weight, high impact strength, good weather resistance, etc. and can be used as a substitute of glass in solar energy utilization technology. Difference in the roughness of materials can lead to the difference in the adhesion of dust to their surfaces. In this paper, 194 days of experimental tests were conducted using PMMA as the substrate to analyze the effect of different concentrations of nano titanium dioxide coating on the dust accumulation at different tilt angles in a natural environment. The results show that the higher the coating concentration, the stronger the surface hydrophilicity and the better the self‐cleaning effect. However, when the coating concentration is up to 1.10%, the surface adhesion of the sample has been reduced to a certain level. Its continued increase would have little effect on the surface dust accumulation density. At this point, the coating self‐cleaning effect reaches a state of approximate saturation. Meanwhile, rainfall plays a key role in achieving the coating self‐cleaning effect. The dust accumulation reduction coefficients of the samples in the period of significantly affected by rainfall are relatively larger. To quantitatively express the self‐cleaning effect of the coating, a prediction model for the dust accumulation reduction coefficient under different tilt angles has been established. The values of rainfall in which the coating exerts significant self‐cleaning effect have also been summarized. It is found that the greater the tilt angle, the smaller the values of effective rainfall, which is mainly influenced by the partial force of gravity parallel downward along the sample. Meanwhile, the prediction model of the cleaning cycle of the sample surface was established in the interval of the accumulated dust concentration between 0 and 3.50 g/m 2 . When the tilt angle is 0°, the cleaning cycle is 35 days; when the tilt angle is 25°, the cleaning cycle is extended to 37 days.