Predictability of color changes of wood used indoor - A new approach to evaluate the color change as a function of the radiation dose

木材的光学性质表现出很高的多样性，并取决于木材中存在的发色官能团和生色团系统。不同树种之间以及同一木材树种内的颜色都有明显的差异。在自然老化过程中，木材会发生颜色变化，这主要是由于紫外线和可见光的辐射以及由此引起的光氧化作用造成的。该项目的目的是将关键数字转换为数据库模型，以便能够根据辐射剂量评估木材的化学和颜色变化。这包括通过深度剖面对变化进行评估。总体而言，研究问题是基于以下假设来处理的：·木材在室内自然阳光暴露(T_N)和人工模拟室内UV/Vis暴露(T_A)期间的颜色和化学变化是已知的：a)如果这两种暴露之间存在特定物种的关系，则可以使用补偿曲线来描述这些关系。参数可以用广义最小二乘估计法进行计算。对于假设的关系t_n=z*t_a，然后可以确定移动因子(Z)。b)当光诱导颜色和化学变化发生时，可以使用探索性数据分析和多元统计(主成分分析，PCA)的结构发现方法来检查这些相关性。c)如果辐射暴露具有短期的颜色和化学影响，则可以通过线性回归来推断长期的变化。·如果阳光暴露可以被指定为时间的函数，它也可以被指定为辐射剂量的函数(基于累积面积的功率密度)。·透过窗户玻璃的UV/VIS光在不同深度穿透各种类型的木材：表面辐射的影响距离木材表面越远，颜色和化学变化就越小。如果这些变化随着渗透深度的增加而减弱，这将导致木材物质中的深度剖面可以通过颜色和化学方法进行测量。·如果对计划测量的评估作为辐射剂量的函数，而不是作为时间的函数，产生启发性的结果，则可以预测变化。·如果从前面的研究假设中出现新的发现，那么在为木材材料开发和定制的材料测试中必须紧急考虑这些发现。

The optical properties of wood show a high variety and depend on the chromophoric functional groups and chromophore systems present in the wood. Noticeable color variations are found both between different species as well as within a wood species. During natural aging, woodundergoes a color change, which is mainly caused by radiation of ultraviolet and visible light and the hereby induced photo-oxidation. The aim of this project is to convert key figures into a databased modelling in order to be able to evaluate the chemical and color changes of wood based on the radiation dose. This includes the evaluation of the changes via depth profiles. Overall, research problems are dealt with on the basis of the following hypotheses: • Color and chemical changes in wood during natural sunlight exposure indoors (t_n) and during artificially simulated UV/Vis exposure indoors (t_a) are known: a) If there are species-specific relationships between the two exposures, these can be described mathematically using a compensation curve. The parameters can be calculated using the generalized least squares estimation method. For the assumed relationship t_n = z * t_a, the shift factors (z) can then be determined.b) When light-induced color and chemical changes occur, these can be checked for correlations using a structure-discovering method from explorative data analysis and multivariate statistics (principal component analysis, PCA).c) If the irradiation exposures have short-term color and chemical effects, then long-term changes can be deduced via linear regressions.• If the sunlight exposure can be specified as a function of time, then it can also be specified as a function of radiation dose (accumulated area-based power density).• UV/Vis light filtered through window glass penetrates various types of wood at different depths: The further away the effect of surface-based radiation is from the wood surface, the lower the color and chemical changes. If the changes are attenuated with increasing penetration depth, this results in depth profiles in the wood substance that can be measured color-wise and chemically.• If the evaluation of the planned measurements as a function of radiation dose, rather than as a function of time, produces revealing findings, then changes can be predicted.• If new findings emerge from the preceding research hypotheses, then these must urgently be taken into account in material tests that are to be developed and tailored to the material wood.