Moisture-curable polyurethane (MCPU) is a specifically designed material for the consolidation of fragile cultural objects in high-humidity environments. In order to solve the problem of its susceptibility to yellowing due to heat ageing, polyhedral oligomeric silsesquioxane (POSS) was added to the MCPU to prepare POSS/MCPU. The appearance, stability and mechanical properties of the POSS/MCPU films were characterized using a UV–Vis spectrophotometer, a gloss meter, a colorimeter, a thermal analyzer and a universal material testing machine. The results showed that the films are colorless and transparent and have a light transmission of over 80%. The addition of POSS has almost no effect on the chromaticity of the MCPU, while the thermal stability of the POSS/MCPU is improved compared to the pristine MCPU. The modified film is 2.50 times more resistant to yellowing by heat. The addition of POSS also simultaneously enhances the strength and toughness of the film. Using POSS/MCPU to reinforce the fragile object, the material was found to be significantly effective, indicating it has the potential to be used during the extraction of fragile cultural objects from archaeological sites.Keywords:conservation materials;moisture-curable polyurethane;POSS;consolidant
The moss colonization on the surface of historic buildings could result not only in a biodeterioration but also in an aesthetical damage. In this study, some mixtures of consolidant (MMH) and GO@CuO hybrids were developed to control moss growth on the surface of weathered sandstone. An innovative aspect of the study was that, by using GO as the intermediate, the CuO nanoparticles were anchored to the MMH consolidant. This method could effectively improve the binding force between CuO nanoparticles and the stone substrate and make it not be washed away by rainfall. Several formulations have been prepared, applied on weathered sandstone specimens, and tested in laboratory to investigate the impact of GO@CuO hybrids addition on consolidation performance. The complex consolidants were subjected to an antibiological activity assay to assess their capability to inactivate moss spores. The complex consolidants were also applied to the specimens covered with mosses. The obtained results demonstrated that the consolidant loaded with GO@CuO hybrids were effective in consolidating the weathered substrate and preventing moss growth on its surface. Additionally, the complex consolidant also had the function of controlling re-colonization of moss after conservation treatment.
Xing Xing Wang,Guan Cheng Jiang,Guo Shuai Wang,Li Li Yang,Yin Bo He,Xiao Ya Wu
In South China Sea, the natural gas hydrates are usually reserved in argillaceous siltstones. These argillaceous siltstones are weakly cemented and incorporated with the solid hydrates. During the drilling process, the natural gas hydrates may decompose unexpectedly, resulting in the wellbore collapse. To improve the stability of the wellbore, this study develops a wellbore strengthener for water-based drilling fluids used in argillaceous siltstones. Tannic acid/polyvinyl (TA/PVA) alcohol has been adopted for preparing the wellbore stabilizer. A series of experiments have been conducted to investigate the effects of newly developed wellbore strengthener on the mechanical properties of the argillaceous siltstones as well as its mechanisms on the wellbore stability. The experimental results show that the wellbore strengthener developed in this study can significantly improve the compressive strengths of the argillaceous siltstone cores. The AFM characterizations indicate that the adhesion force between the silica (the major compound in argillaceous siltstones) microspheres and the wellbore strengthener can reach up to 2138 nN. Moreover, the SEM images visually show good cementation of the argillaceous siltstones after being treated by the wellbore strengthener. In addition, the wellbore strengthener can also assist in reducing the fluid losses of water-based drilling fluids. It is hopeful that the wellbore strengthener provided in this study help the development of underwater natural gas hydrates.
危险品化学品经营许可证（带存储）