Understanding moisture’s impact on materials’ mechanical properties is crucial for both fundamental research and practical applications. In this work, we introduce an integrated experimental approach that combines dynamic mechanical analysis (DMA) under controlled humidity and temperature with simultaneous small- and wide-angle X-ray scattering (SWAXS). This setup leverages high-brilliance X-rays from the MAX IV synchrotron (Lund, Sweden), utilizing the CoSAXS and ForMAX [1] beamlines to enable real-time observation of both macroscopic mechanical response and nanostructural evolution under controlled environmental conditions.

To demonstrate its cross-scale capabilities, we applied this approach to two materials with distinct moisture-driven behaviors. For poly(lactic acid) (PLA), we examined moisture effects on cold crystallization dynamics, comparing neat PLA to composites containing cellulose nanocrystals (CNC) or wood fibers (WF). Tracking changes in storage (G′) and loss (G″) moduli revealed how moisture-induced crystallization influences bulk mechanical properties. We also investigated dialcohol cellulose (DAC) with three modifications to determine how moisture-induced swelling affects mechanical properties and how these changes manifest in SAXS/WAXS patterns. These results demonstrate that coupling SWAXS with mechanical spectroscopy yields deeper insight into how moisture-driven nanostructural changes manifest in macroscopic mechanical behavior.