The use of wood-based materials in the automotive industry is currently under discussion and investigation. One of the major material requirements for such applications is sufficient weathering stability. This can be demonstrated by an accelerated aging process in which the samples are exposed to changing climatic conditions and a spray mist of an aqueous NaCl solution. The effects of media salt (NaCl) on the mechanical and physical properties of wood have scarcely been investigated. The presented study investigated the changes in bending strength (MOR), modulus of elasticity (MOE), and impact bending strength (α) of naturally and artificially weathered oak (Quercus spp.) and birch (Betula pendula Roth) wood. The tests provided comparable results. The decrease under natural weathering of oak was 3.73%, 4.69%, and 6.45% for MOR, MOE, and α. Under artificial weathering the decrease observed for oak was 7.33%, 10.87%, and 16.29% and 3.2%, 8.21%, and 4.03% for birch respectively. It is remarkable that α increased for birch wood at the beginning of the artificial weathering cycles. The penetration of the aqueous NaCl solution into the wood substance resulted in an increase in the wood’s equilibrium moisture content (EMC), which can be explained by the stronger hygroscopic properties of NaCl compared to wood. The higher impact strength at the beginning of artificial weathering can be partly explained by this increase in EMC. In order to investigate the penetration behavior of salt into the wood substrate, the artificially weathered samples were examined by means of energy dispersive X-ray analysis (EDX) and it was shown that the salt concentration changes significantly over the weathering cycles and sample cross-section.

The tree of heaven (Ailanthus altissima (Mill.) Swingle) is a neophyte that is classified as highly invasive. This study shows that in contrast to the challenges the forestry industry faces with this species, the wood of the tree of heaven has considerable promising technological and pulp and paper properties. The attractive wood is hardly distinguishable from European ash (Fraxinus excelsior L.) both visually and in its mechanical properties. Consequently, the wood of the tree of heaven also has a high potential for load-bearing and solid-wood applications. A final technological evaluation of the wood is challenging because the tree of heaven is currently being massively combated, which negatively affects the quality of the roundwood material. Therefore, noncontrolled free-standing trees were examined in this study.