Polycarbonate is a good material for covering and protecting cultural heritage sites because of its durability, mechanical properties, and transparency. However, polycarbonate degrades under environmental weathering with a significant decrease of physical and mechanical properties and loss of transparency. In this work, the contemporary presence of ultraviolet irradiation and different temperature and moisture conditions have been taken into account to study the environmental degradation of this polymer with regard to its mechanical and optical properties. The photo-oxidation reactions cause a decrease in the molecular weight and the formation of many oxygenated species. The hydrolytic scission, instead, gives rise to a remarkable reduction in the molecular weight. These two different degradation mechanisms do not seem interconnected because at the lowest degradation temperature and high humidity levels, the reduction of the molecular weight is more pronounced than that observed at the highest temperature but at a lower humidity level. Transparency decreases with the degradative processes, but even after severe degradation the loss of transparency is only about 10%. The yellowness index increases during the first stages of degradation, which has been attributed to the fast formation of carbonyl groups due to photo-oxidation.

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环境条件对聚碳酸酯用于文化遗产保护的耐久性的影响

聚碳酸酯具有耐久性、机械性能和透明度，是覆盖和保护文化遗产的良好材料。然而，聚碳酸酯在环境风化下降解，物理和机械性能显着下降，透明度降低。在这项工作中，考虑到了当代存在的紫外线照射和不同的温度和湿度条件，以研究这种聚合物在机械和光学性能方面的环境降解。光氧化反应导致分子量降低并形成许多含氧物质。相反，水解断裂引起分子量的显着降低。这两种不同的降解机制似乎并不相互关联，因为在最低降解温度和高湿度水平下，分子量的降低比在最高温度但在较低湿度水平下观察到的更明显。透明度随着降解过程而降低，但即使在严重降解之后，透明度的损失也只有约 10%。在降解的第一阶段，黄度指数增加，这归因于光氧化导致羰基的快速形成。但即使在严重降解后，透明度的损失也只有 10% 左右。在降解的第一阶段，黄度指数增加，这归因于光氧化导致羰基的快速形成。但即使在严重降解后，透明度的损失也只有 10% 左右。在降解的第一阶段，黄度指数增加，这归因于光氧化导致羰基的快速形成。