The reaction between epoxide and cyanurate is believed to consist of the insertion of the epoxide into the triazine ring-oxygen bond, followed by isomerization; However, definitive evidence has not yet been obtained. Therefore, in this study, we investigated the reaction behavior using model systems for both the insertion and isomerization processes. We found that the insertion step could be promoted by adding 4-dimethylaminopyridine, while the isomerization step could be facilitated by the addition of ethylene glycol, a protic polar compound.

To enhance the thermal conductivity of epoxy resin composites, we focused on trans-resveratrol (tRES), a natural polyphenol with a rigid conjugated structure, as a phenolic curing agent, and developed bio-based high thermal conductivity and insulating composites. However, the high melting point of tRES posed challenges for mixing and molding during composite preparation. To address this, we utilized the photoisomerization reaction of the stilbene structure in tRES to synthesize its cis isomer (cRES). The melting behavior of cRES showed a significant reduction in melting point to approximately 100℃, and cRES also demonstrated superior compatibility with epoxy resins.Using cRES as a hardener under the presence of a triphenylphosphine catalyst, we cured typical biphenyl epoxy resin at 175℃. This resulted in a 25% higher thermal diffusivity compared to conventional novolac hardener (OCN), confirming the potential of cRES for improving thermal conductivity. Furthermore, combining this curing system with 90 wt% alumina filler produced a composite with a 32% biomass ratio relative to the total resin content. This system exhibited excellent molding flowability and achieved a 12% higher thermal conductivity than the OCN-based system. These results indicate that this environmentally friendly, high thermal conductivity material has potential applications as an encapsulant for next-generation power semiconductor packages.

In this study, tannic acid (TA), a naturally derived polyphenol, was employed as an additive to evaluate its effects on the thermal and mechanical properties of two biodegradable polyesters: poly(butylene adipate-co-terephthalate) (PBAT) and poly(butylene succinate) (PBS). TA possesses a large number of phenolic hydroxyl and carbonyl groups and is expected to interact physically with polyester chains, thereby affecting their molecular mobility. According to dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC), Tg increased in TA-containing samples, with DMA showing a Tg shift of approximately 30 °C. In terms of mechanical properties, TA addition led to a significant increase in elongation at break for PBS. The results suggest that TA serves as a functional interaction modifier that can regulate polyester properties through multivalent physical interactions and provides a promising strategy for the functional design of biodegradable polymer materials.

Resole is obtained from phenol and formaldehyde under basic conditions and is cured by heating. We try to prepare wight-saving cured resole resins using cyclic phenolic compounds as curing agents. Novel resole resins (R-CR(10)s) were obtained by curing resole with calix[4]resorcinarene (CR(10)), which is a cyclic tetramer consisting of resorcinol backbone and undecanal. The resulting R-CR(10)s showed excellent heat resistance and light-weight properties compared to the Resol resin without curing agents. Furthermore, TR-CR(10), in which CR(10)s were cross-linked by triphenyl methane linkage, was prepared and used as the curing agent for the resole resins. R-TR-CR(10)s were prepared from resole with TR-CR(10) and showed excellent heat resistance and high light-weight properties. It was found that the light-weight properties and the higher heat resistance for cured resole resins could be gotten at the same time by using cyclic phenolic compounds as curing agents.

We synthesized modified lignin novolac type benzoxazine using polyethylene glycol modified lignin, a new forest-derived material, and evaluated the characteristics of modified lignin novolac type benzoxazine resin obtained by polymerization. As a result, modified lignin novolac type benzoxazine can be molded at a low temperature and in a shorter time than conventional bisphenol F type benzoxazine. In addition, modified lignin novolac type benzoxazine resin had excellent heat resistance, mechanical strength, electrical insulation and water resistance.