Vicinal tricarbonyl compounds, chemical species having three contiguous carbonyl groups, readily react withvarious nucleophiles, such as water, alcohols, thiols, and aromatic amines without any catalyst, and moreover,these addition reactions are reversible under appropriate conditions. Therefore, reversible crosslinking–decrosslinking systems can be constructed by incorporating vicinal tricarbonyl structures into polymers. Thisreview deals with 1） the synthetic methods, characteristics, and reactivity of vicinal tricarbonyl compounds,and 2） network formation based on the reaction of vicinal tricarbonyl compound and polymer recycling bydecrosslinking of the networked polymers.

In situ analysis of the residual stress in a glass-fiber-reinforced phenolic resin and copper foil compositematerial during curing and thermal-cycle testing was performed via time-resolved X-ray diffractionmeasurements. The semi-cured resin–copper composite exhibited a large compressive stress in copper beforecuring. This indicates the stress-free adhesive interface between resin and copper was first formed when theresin melted in the molding process and the magnitude of the thermal contraction of the resin was largerthan that of copper in the subsequent cooling to room temperature, which was caused by the difference inthe coefficients of thermal expansion between resin and copper. This compressive stress decreased as thetemperature was increased to curing temperature. As the curing proceeded at 180℃ , the compressive stressin the copper again increased because of cure shrinkage of the resin. When the cured sample was reheated tothe curing temperature, the compressive stress in the copper at 180℃ was relaxed. This thermal-annealinginducedstress relaxation suggests that cross-linking reactions during the curing process caused structuralstrains and the relaxation of the cross-link strain induced the stress relaxation.

Clear understanding of wood ageing is practically important for the appropriate maintenance and restorationof old wooden cultural properties as well as the quality enhancement of wooden musical instruments.However， it is difficult to discuss the effects of ageing by comparing new wood and aged wood， because thephysical properties of wood varies widely even in a same species. Many attempts have been made for theartificial acceleration of ageing by oven heating， but these have little reality because the effects of moistureare not considered in many cases. This paper introduces recent development of time-temperature-humiditysuperposition allowing precise prediction of wood ageing and artificial reproduction of aged wood.