Energy problems have become increasingly prominent. The use of thermal insulation materials is an effective measure to save energy. As an efficient energy-saving material, nanocellulose aerogels have broad application prospects. However, nanocellulose aerogels have problems such as poor mechanical properties, high flammability, and they easily absorbs water from the environment. These defects restrict their thermal insulation performance and severely limit their application. This review analyzes the thermal insulation mechanism of nanocellulose aerogels and summarizes the methods of preparing them from biomass raw materials. In addition, aiming at the inherent defects of nanocellulose aerogels, this review focuses on the methods used to improve their mechanical properties, flame retardancy, and hydrophobicity in order to prepare high-performance thermal insulation materials in line with the concept of sustainable development, thereby promoting energy conservation, rational use, and expanding the application of nanocellulose aerogels.

Three kinds of typical Chinese traditional mortise-tenon joints were tested. The effects of sparging on the deformation, hysteretic behavior, strength and stiffness degradation, and energy dissipation of the mortise-tenon joints were studied via low-cycle reversed loading tests with and without a ‘Que-Ti’ component. The results showed the following: the bearing capacity of the straight-tenon joint was the strongest, and the hysteretic loop of the through-tenon joint and half-tenon joint were asymmetric due to the asymmetry of the tenon form. The half-tenon joint was most likely to pull out the tenon, and the tenon pulling condition of the half-tenon joint can be effectively alleviated by adding a ‘Que-Ti’ component. From the perspective of energy consumption, it was found that the energy consumption capacity of the mortise-tenon joints after adding a ‘Que-Ti’ component was stronger than the joints without a ‘Que-Ti’ component. This shows that the ‘Que-Ti’ can be used as an effective component in terms of enhancing the mechanical properties of the mortise-tenon joints.

The load-displacement curves of six types of roof-to-wall connection joints were obtained through uplift experiments, while the mechanical properties of each type of joint were compared and analyzed, and the applicability of each joint was verified by the Foschi load-displacement curve model simulation. The specimens were made of three kinds of wood (Pinus sylvestris (PS), Spruce-Pine-Fir (SPF), and Douglas fir (DF)) and two different metal connectors (A-type and B-type), and then the monotonic pullout tests were conducted on each specimen. The failure modes of each group of specimens were analyzed, and the characteristic values analysis method was used to analyze and compare the characteristic values of the load-displacement curves of each specimen, including six characteristic values: maximum load, yield load, deformation capacity, energy dissipation capacity, ductility ratio, and initial stiffness. The results showed that the load capacity of TA group (specimens with A-type metal connectors) was much greater than that of TB group (specimens with B-type metal connectors). The specimens made of DF had the best mechanical performance, but the specimens of DF group were prone to brittle failure. Finally, the fitting parameters of the Foschi model applicable to such joints were obtained.