The effect of polyethersulfone (PES) blend with bisphenol E dicyanate (DCBE) on the flame resistance of the cured resins was investigated. The DCBE/15 wt% PES blend compositions were cured at 200 ℃ using three different temperature ramps. The size of phase structure via reaction-induced phase separation and the glass transition temperatures (T_gs) of the two phases varied with the temperature ramps. The slower temperature ramps resulted in smaller phase structure sizes and closer T_gs of the two phases. When the phase structure size was in the middle (about 10 μm), the self-extinguishing time was the shortest and the flame resistance was the highest among them. When the phase structure size was large (20－40 μm), debonding at the interface of the phases occurred upon ignition, resulting in a decrease in flame resistance. On the other hand, when the phase structure size was small (2－3 μm) also, the flame resistance was lower than that of the middle size. This suggested that the role of the PES-rich phase as a flame retardant domain was reduced due to increased incorporation of DCBE components in the PES-rich phase.

Carbon Fiber Reinforced Plastics (CFRP) is a lightweight and high-strength material, which make its usage expanding in many industries. We have been studying a recycling method of epoxy resin using nitric acid under mild condition, and in this research, this method was used as a basis to develop CFRP recycling method. The physical properties of recovered carbon fibers were evaluated to assess the applicability of this method. CFRP waste which is projected to be disposed in large quantity in the future was prepared as a sample. By immersing this CFRP specimen into 8 M of nitric acid at 80℃ for 24 hours, both resin-free carbon fiber and recyclable decomposed resin could be recovered. The recovered carbon fiber shows higher value of tensile strength and interfacial shear strength compared to virgin carbon fiber. Therefore, it was shown that this nitric acid decomposition method is an effective method for carbon fiber recovery.

It is considered that the novolac resin which is compatible with high flexibility and high drawing ability by the introduction of bisphenol (bis-PhOH) component with the bulky component represented by isopropylidene group such as bisphenol A (BisA), bisphenol C (BisC), and bisphenol B (BisB) is found. Then, when bis-PhOH component of molecular structure which suppressed the bulkiness was introduced, characteristics of flexibility and drawing ability should be reduced. In order to verify this, a novolac resin incorporating bisphenol E (BisE, 4, 4'-ethylidenebisphenol) with an ethylidene group was newly synthesized and its characteristics were investigated. By incorporating formaldehyde (Form) and glutaraldehyde (Glu) into the crosslinking agent, relatively high molecular weight novolac resins of 2100 ～ 2400 and 3900 ～ 6800, respectively, were obtained. However, dissolving rate for alkaline aqueous solution (DR) ≧1400 Å/s was obtained, indicating a high property of DR. Therefore, it did not come to find the BisE system novolac resin in which both of drawing possible range and remaining film rate satisfied the standard. And, on the flexibility, the addition of the flexibility could not be almost recognized in the case of BisE/Form novolac resin. However, in the case of BisE/Glu novolac resin, the flexibility which was equivalent to BisA/Form and BisC/Form novolac resin could be expressed. Next, the flexibility of bis-PhOH-incorporated novolac resins decreased in the order of BisA/Glu, BisB/Glu, and BisC/Glu novolac resins >> BisA/Form, BisB/Form, BisC/Form, and BisE/Glu novolac resins >> BisE/Form novolac resins In this way, the BisE system novolac resin with the ethylidene group having a little suppressed bulky skeleton greatly lowered both characteristics of flexibility and lithography.

A novel naphthalene based epoxy resin having an azomethine structure (GNMB) was synthesized, and the properties of the cured polymer using phenol novolac as a hardener were compared with those of the phenyl ring based epoxy resin having an azomethine structure (GPMB) and the bisphenol A type epoxy resin (DGBPA). The glass transition temperature of the GNMB polymer was 172℃, which was 11℃ and 45℃ higher than those of the GPMB, and DGBPA polymers, respectively. In addition, the thermal conductivity of the GNMB polymer was 0.28 W/m・K, which was 1.4 times higher than that of the DGBPA polymer.

As a new type of curing agent for epoxy resins, the imidazolium salt-based ionic liquids (ILs) have been actively studied over the past decade or so. The 1-alkyl-3-methylimidazolium cation is a dominant type of cation component in the imidazolium salt-based IL that is possible to polymerize epoxy resins by itself. The imidazolium-type IL bearing the 1-alkyl substituent of up to 6 carbon atoms had usually low viscosity and was considered suitable as an epoxy resin curing agent.The anion component in the IL has larger influence on curability and on the physical properties of the cured epoxy resin rather than the cation component. The epoxy resin formulation containing the imidazolium salt-based IL exhibits a much longer pot life than that of the generally used imidazole curing systems. When the optimum amount of IL is added to the epoxy resin formulation for curing, the mechanical properties are comparable to those of the imidazole cured epoxy resin, and higher T_g is often obtained.