Preliminary Study On Restoration Materials For Wall Paintings In Humid Environment

In this paper, the main work is to select hydrolysis catalysts for TEOS and modifier and study the film performance of the modifier in moisture circumstances.The research drawn:(1) Hydrochloric acid, aluminium trichloride, dibutyltin dilaurate have good catalytic effects on TEOS. The film of TEOS is transparent when hydrochloric acid and aluminium trichloride is used as catalysts, but it cracks. Tetrabutyl titanate, oxalic acid dihydrate, citric acid monohydrate have some catalytic effects on TEOS, but no film is obtained. Sodium fluoride, boric acid, ammonium hydroxide, N-N-di-methylformamide, lithium bromide monohydrate, aluminum oxide silicate have little catalytic effects on the TEOS.(2) The film cracking problems can not be sloved when TEOS compounded with methyltrimethoxysilane, methyltriethoxysilane, trimethoxypropylsilane, orpropyltriethoysiane separately. By adding chemical additives N-N-dimethylforma-mide, curing time of compounded material was shorted, but the film cracking problem can not be completely solved.(3) TEOS oligomers modified by alkyl siloxane in non-homogeneous reaction have good film-forming performances in dry environment compared with TEOS used alone. In Oligomer synthesis process, under the same conditions that molar ratio the monomer and water is greater than 1.67, the amount of hydrochloric acid is about 0.05% of monomers, the reaction time is 6h in heterogeneous conditions, the four oligomers have good film-forming performances in dry circumstances by controlling mole ratio of TEOS and WD-921 is 1 to 2, mole ratio of TEOS and JHN313 is 1 to 1.25, mole ratio of JHN318 TEOS is 1.5 to 1, mole ratio of TEOS and JNH3112 is 2 to 1. Oligomers of WD-921 and TEOS have good film-forming performances in the himud environment, while oligomers of the other monomers and TEOS have poor film-forming performances.