In recent years, benzoxazines have been reported as a novel high performance thermosetting resin with ring-opening reactivity, which has superior properties such as high heat-resistance and glass transition temperature (Tg). Inthisstudy, new series of bi-functional benzoxazines were synthesized from aromatic diamines, and their properties such as hardening behavior, thermal and mechanical properties were examined. The benzoxazines exhibited exothermic reactivity at a temperature range of 220～230℃. The 5% weight loss temperatures of cured benzoxazines were 320～350℃. The benzoxazines showed higher residual weights at 700℃, compared with bi-functional benzoxazines derived from bisphenols. The Tg and crosslinking density were analyzed and calculated from the results of the dynamic mechanical analysis. The Tg of benzoxazine depended on the spacer structure. In addition, the Tg of benzoxazine became higher with increase of crosslinking density. The storage modulus at ordinary temperature was lowered with decrease of crosslinking density.

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Effects of unsteady rate stirring mode on the particle size and the size distribution were thoroughly investigated in the preparation of cross-linked polystyrene and chloromethyl resins under suspension polymerization conditions. Thus, unsteady rate stirring at low rate (e.g. 200 rpm) generally gave both resins in smaller size and narrower distribution with comparison to the usual steady rate stirring under the same conditions other than the stirring mode. When the suspension polymerization was carried out without an organic solvent such as chlorobenzene for dilution of monomer phase, the aggregated primitive particles were often observed by microphotographs. Especially, unsteady mode at low rate can give monodispersed cross-linked resin beads.

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To prevent the degradation of structural glued laminated timbers (glulams) exposed to outdoor conditions, we investigated the reinforcement of those surfaces with poly vinyl alcohol fiber sheets (PVA-S). First, we studied the bonding of PVA-S on a wood surface with epoxy resin adhesive, including an examination of compatibility among wood preservatives (ACQ, AAC, NZN, NCU, CUAZ2), PVA-S and adhesive resin. Next, we studied the waterproof properties of PVA-S, the decrease of dimension changes and prevention of cracks or delaminations in reinforced glulam. We also investigated the influence of PVA-S reinforcement on the distribution of glulam moisture content via an outdoor exposure test. High bonding durability was obtained for wood-PVA-S adhesion, regardless of the pressing method, and the adhesion of preservatives-treated wood and PVA-S provided adequate bonding durability. Water did not penetrate below the surface of glulams with PVA-S lamination. Reinforcement with PVA-S decreased dimension changes of glulams and prevented the occurrence of delaminations or cracks during cyclic wet-dry treatment. PVA-S reinforcement prevented an increase of moisture content in glulams exposed to outdoor conditions.

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