Performance Study of Lightweight Insulating Mortar Reinforced with Straw Fiber.

The current research aimed to develop lightweight, environmentally friendly mortar materials using crop straw fibers with better insulation properties. The lightweight mortar samples were tested for moisture content, thermal conductivity and compressive strength on days 3, 7 and 28, respectively. Scanning electron tomography (SEM) was performed on the fiber-matrix bonding interface and internal fiber structure. The permeability rating was also measured to check the impermeability of the lightweight fiber mortar. Due to the high hygroscopicity of plant fibers, the thermal conductivity of the mortar was high at the initial molding stage; the thermal conductivity measured at day 28 decreased with increasing fiber content, while the mechanical properties gradually decreased. The impermeability test showed that the straw fiber mortar had better impermeability than the standard mortar. However, with the addition of 2% of 10 mm long fibers, we increased the compressive strength and thermal insulation properties. Numerical simulations verified that the fiber insulation mortar has good thermal insulation properties in high-temperature tunnels.

Degradable self-adhesive epidermal sensors prepared from conductive nanocomposite hydrogel.

Conductive hydrogel-based epidermal sensors are attracting significant interest due to their great potential in soft robotics, electronic skins, bioelectronics and personalized healthcare monitoring. However, the conventional conductive hydrogel-based epidermal sensors cannot be degraded, resulting in the significant problem of waste, which will gradually increase the burden on the environment. Herein, degradable adhesive epidermal sensors were assembled using conductive nanocomposite hydrogels, which were prepared via the conformal coating of cellulose nanofiber (CNF) networks and supramolecular interaction among CNF, polydopamine (PDA), Fe3+, and polyacrylamide (PAM). They exhibited superior mechanical properties, reliable degradability (30 days in water), and excellent self-adhesiveness. The obtained hydrogels could be assembled as self-adhesive, degradable epidermal sensors for real-time human motion monitoring. Air could be sucked into the hydrogels during their swelling process, thereby oxidizing the tris-catechol-Fe3+ complexes and releasing Fe3+. Finally, the polymer networks were degraded via a Fenton-like reaction dominated by S2O82- and Fe(ii/iii) with the help of the catechol groups of PDA. This work paves the way for the potential fabrication of degradable, and self-adhesive epidermal sensors for applications in human-machine interactions, implantable bioelectronics, and personalized healthcare monitoring.