The cationic ring-opening copolymerization of cyclic carbonate having a norbornene backbone (NCC) and bisphenol A type epoxy resin was carried out by a thermal latent initiator 1, and properties of the resulting cross-linked copolymers were evaluated. As the results, the homogeneous copolymers were prepared under appropriate conditions for curing reaction. In the copolymerization, a lower value in the volume shrinkage rate of the whole system was observed, compared with DGEBA homopolymer system. The Tgs of the obtained copolymers showed to be lower than that of DGEBA homopolymer. Furthermore, the decrease of internal stress was also observed both in the curing and cooling processes.

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New green nanocomposites from epoxidized plant oils and an oxetane-containing silane coupling agent have been developed. The acid-catalyzed curing of epoxidized soybean and linseed oils (ESO and ELO, respectively) with 3-ethyl-3- ((3- (triethoxysilyl) propoxy) methyl) oxetane (TESOX) produced transparent nanocomposite coatings with high gloss surface, in which the organic and inorganic components were linked via covalent bonding. The universal hardness and Young's modulus of the coating increased as a function of the feed ratio of TESOX. The nanocomposites showed improved mechanical properties, as compared with those of the cured polymers of the epoxidized plant oils. The coating and mechanical properties of the ELO-TESOX nanocomposite were superior to those of the ESO-based nanocomposite.

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Two types of organophilic-montmorillonite (treated with dimethyldioctadecyl ammonium chloride or ω-carboxy dodecanoic ammonium chloride) were dispersed into the epoxy/acrylate-based IPN which had been prepared by a simultaneous polymerization technique. On curing, there were used methylhexahydrophthalic anhydride as a curing agent for the epoxy resin, and AIBN, BPO or DTBPO as a radical initiator for the acrylate, respectively. The cured products were analyzed by X-ray diffraction, TEM observation, dynamic mechanical analysis and testing fracture toughness. They were the mixtures of intercalated and exfoliated nanocomposites in all the combination of every curing agent and organophilic-montmorillonite system. The improvements in the compatibility the epoxy resin with the acrylate, and also in the fracture toughness of products were observed by adding the organophilic-montmorillonites.

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Epoxy casting materials are used widely in heavy apparatus because of their excellent mechanical and electrical properties. However, epoxy resins are very brittle and their resistance to thermal shock is poor generally. In this study, the modification of an anhydride-cured epoxy resin system with rigid silica particles or a flexible silicone gel was investigated to improve the toughness. The addition of either the modifier into the epoxy system was effective to increase the fracture toughness of the cured resin. The diameter of the silicone gel in the cured epoxy resin was successfully controlled by use of silicone oil as an additional modifier. More effective modification of the resin was attained in the hybrid system, in which both the fillers were added together into the resin system. Such an epoxy resin system modified with the hybrid fillers was suitable as casting materials : the resin system has good flow properties before curing, and has excellent adhesive and insulating properties as well as high fracture toughness after curing.

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The authors decomposed an epoxy resin cured with an amine by using a nitric acid solution, and extracted compounds were recovered by ethyl acetate to be added to the virgin epoxy resin and cured with an acid anhydride. The cured resin showed good mechanical properties. In this study, aiming at the appearance of 4 peaks in the molecular weight distribution of the extracted compounds, each peak component was fractionated by chromatography. The compounds of 4 kinds with respectively different molecular weight distribution were added to the virgin epoxy resin individually and cured with the acid anhydride to evaluate mechanical properties. Generally speaking, the higher the molecular weight of the extracted component, the better were the mechanical properties and thermal stability. Decomposing conditions for efficiently obtaining the extract with high molecular weight were investigated with respect to the concentration of nitric acid solution and the proceeding time of decomposition. The extract from the compounds which decomposed by a high conc. nitric acid for a short time contained plenty of the high molecular weight component. It became clear that there was a correlation between the content of high molecular weight component and the mechanical strength of recycled materials.

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Formation of calixresorcinarene by acid-catalyzed degradation of resorcinol novolac derivative is described. Methylated resorcinol novolac (2) was prepared by hydrochloric acid-catalyzed condensation of 1, 3-dimethoxybenzene (resorcinol dimethyl ether) with paraformaldehyde in 2-ethoxyethanol at 50°C. And then 2 and conc. sulfuric acid (catalyst) in acetic acid solution was heated at 100°C for 5h to give calix [4] resorcinarene octamethyl ether (3) in 26% isolated yield. The structures of 2 and 3 were confirmed by ¹H NMR, IR and GPC analysis. This reaction will be developed for a recycling of thermosetting phenolic resins.

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Conventional phenolic resins based on either a resole or a novolac with hexamethylenetetramine is usually cured through condensation reaction, evolving several volatiles while curing. Cure with evolution of volatiles necessitates the application of pressure during molding to get void-free molded articles. But recently, there have been investigated new type phenolic resins cured through addition reactions.
In this article, certain kinds of addiotion-curable phenolic resins are reviewed. The intermediates from these phenolic resin have such functuinal groups as allyl, maleimide, acetylene, nitrile, as well as benzoxiazine ring. These phenolic resins cured through addition resections are superior in heat and flame resistance, and toughness, to those of phenolic resins cured with hexamethylenetetramine. These addition-curable phenolic resins are also suggested to be useful as matrix resins for fiber reinforced plastics.

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