Polymethacrylates having a spiro orthoester group in the side chain were synthesized by the radical polymerization of the corresponding methacrylate and copolymerization with methyl methacrylate. The obtained polymers underwent crosslinking in the presence of a cationic initiator in chlorobenzene at 0°C for 1h to afford the network polymers, which underwent decrosslinking in the presence of a cationic initiator in chlorobenzene at 20°C for 24h to recover the solvent-soluble original polymers.

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The investigation is for improving the phenolic resin's properties, such as toughness, electrical insulation, and water-proof, was performed by lengthening the distance between two crosslinking nodes and lowering the concentration of OH groups in a phenolic resin. In the concrete, a phenolic resin was modified with undecenyl aldehyde (UA) as follows : At first, phenol (P) was reacted with UA under different molar ratios and an acid condition, producing a UA modified phenolic oligomer (UA modified phenol) by addition reaction of both double bond and carbonyl group of UA to phenolic nuclei. Next, formaldehyde was reacted with free phenol and the oligomer mentioned above, producing a UA modified novolac oligomer by co-condensation between them. The latter oligomer had higher average molecular weight than a conventional phenol formaldehyde novolac. Further, the investigation was made on the flowability and curing behavior of molding compounds which were prepared from both the UA modified phenol and novolac, hexamethylenetetramine as a curing agent, and wood flour as a filler. The flowability of the compound from UA modified novolac I (molar ratio UA/P = 0.1/1) and that from UA modified novolac II (UA/P = 0.2/1) were superior to that from the conventional novolac. Onset temperatures of curing reaction for the molding compounds from UA modified novolacs were similar to that from the conventional novolac. The properties of cured test pieces obtained by transfer molding were found as follows : toughness, electrical insulation and water-proof of cured resins from UA modified novolac I and II were superior to those from the conventional novolac, and heat resistance of cured resin from UA modified novolac 1-2 which had higher molecular weight than I or II was superior than that from the conventional novolac.

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As chemical recycling of thermosets, the investigation was performed on the novolac epoxy resinification from a thermal decomposition liquid of paper base phenolic resin wastes. The liquid was prepared by treating the wastes at 600°C for 2 hours under nitrogen gas, in which low distillates were removed. The following was the resinification reactions for this liquid, containing phenol, cresol derivatives and methylcarboxylates, as main components. First, the reaction of novolacs : the liquid was reacted with formalin under an acid condition to obtain the novolac product (PFRO). Another novolac (PFR50) was also obtained from the liquid after adding the same quantity of pure phenol. Second, the reaction to opoxies : the novolac epoxy products, EPNO and EPN50, were synthesized from PFRO and PFR50 ubder the condition of excess epichlorohydrin. Their epoxy equivalent values were about 250 and 390g/eq., respectively. The examination was carried out on a few properties of these epoxies cured with triethylenetetramine (TETA), methylnadic anhydride (MNA) and p, p'-diaminodiphenylmethane (DDM). Tgs of EPN50s were about 50°C higher than those of EPNOs each of which was above 100°C with every curing reagent. Flexural strengths and elastic moduli of the cured EPNs with MNA were nearly equal to cured conventional epoxy resins.

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The Properties of a thermosetting thin film adhesive with a range between 5 and 30 microns were investigated. The strength of adhesion and the heat resistance were found to strongly depend on the film thickness. Flow control of the adhesive film on heat press is necessary to maintain the thickness to an optimum value, while a good flow is important for keeping wettability. Therefore the viscoelastic property of the adhesive film before thermal cure is one of the key factors for reliability. The viscoelastic property after thermal cure, on the other hand, is a good index of heat resistance : it was found tto be a significant correlation between tan¥ and solder heat resistance.

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Recently, organic/inorganic hybrid materials with controled morphology on a scale of nanometer have acquired much interests as a new type of composites. Here, an overview of organic/inorganic hybrid materials, composed of metal oxides or clay materials as inorganic components, is provided with emphasis placed on the morphology-property relationship. The organic/inorganic hybrids are classified by their composition and are described in detail in focus on the synthesis, property, morphology as well as application.

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[in Japanese]

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