SUSTAINABLE BIOPOLYMERS FOR PROTECTION OF MARBLE STATUE’S HEAD FROM GRAECO ROMAN PERIOD (CASE STUDY)

Abstract

Polylactic acid (PLA), Chitosan, and Poly hydroxyalkanoate (PHA) were chosen from among the numerous types of biopolymers as coating agents to examine their efficacy in reducing the impact of air pollutants to the formation of black crust on head of marble statue dating back to the Graeco-Roman period, this head is currently on display at the Grand Egyptian Museum in Cairo (GEM No. 65068). In this study two types of samples used, first category specimens were taken from the lower part of the statue‘s head to characterize the crust and substrate,. According to results, which are obtained from Scanning Electron Microscope ( SEM-EDX) analysis, Micro-Raman spectroscopy, and X-ray diffraction (XRD) analysis, Calcite (CaCO3) is the main component in marble samples, and Gypsum (CaSO4·2H2O) is a common component in the black crust. Second category were an experimental marble samples used to evaluate the protection efficiency of biopolymers. After application, the surface morphology, color change, and water static contact angle of the experimental marble samples were assessed. Finally, the samples were aged artificially to see how resistant they were to solar, ultraviolet, and acidic deterioration. In terms of polylactic acid efficacy, promising results were found due to their properties as hydrophobic behavior, it achieved the highest water static contact angle without affecting color measurements, and then applied in the protection of the marble statue's head.