Effects of particle size and surface treatment on the acoustic emission (AE) characteristics and the tensile strength of epoxy resin filled with spherical silica particles were studied. Four kinds of spherical silica particles having different mean sizes in the range from 6-31 mm were used. The particle content was 70 wt%. In order to improve and decrease the adhesion of the interface between particle and epoxy matrix, particles were treated with silane coupling (A) and silane decoupling (B) agents, respectively. The A- and B-treated particle-filled systems were compared with the untreated particle-filled system. As the particle size increased the tensile strength decreased and AE hits increased. The tensile strength was higher in the order of the A-treated > the untreated > the B-treated systems. Fewer AE hits were generated in both A- and B-treated systems than in the untreated system. Scanning electron microscopic observation of fractured surfaces was carried out to clarify the reason of the above results.

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Epoxidation for thermal decomposition liquids of phenolic resin wastes was investigated. The thermal decomposition liquids were prepared at 600°C for 2 hours under the nitrogen gas and low distillates were removed. Epoxy products were prepared from those liquids, whose main components were a phenol and methylphenol derivatives, by epoxidation. As the epoxy products were monofunctional compounds, physical properties for cured the epoxy products / diglycidyl ether of bisphenol A (DGEBA) blend resins were examined. Tg of the cured resins for the blend resins decreased with an increase in the amount of the epoxy products. And, the cured resins for the blend resins (1 : 1 weight ratio) had a larger peel strength than that for the cured DGEBA resins.

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Recently, the uses as fillers for thermosetting plastics wastes have been proposed. However, phenolic resins gave glassy carbon in about 50% yield at a higher temperature under an inert gas. In this study, molding of carbon precursors prepared in thermal decomposition of phenolic resin wastes and properties of the sintered carbon products were discussed. Carbon precursors were prepared at 600°C under the nitrogen gas, then were crushed and were pulverized by means of a ball mill. Test pieces of the carbon precursors were molded with phenolic resins as a binder by press molding, and were sintered at several temperatures (800-2000°C) under the nitrogen atmosphere. The bending strength of the sintered test pieces increased and the electrical resistivity of those decreased, with an increase in the amount of the binder. For the sintered test piece (sintering temp. : 1500°C ; addition of the binder : 20wt%), the bending strength was about 20Mpa, and the electrical resistivity was about 0.01 Ω cm. It is clear that the sintered products are available as some porous solid materials of carbon.

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The study was conducted on the reaction of amides with glycidylether type epoxides and the reaction of aromatic polyamides with epoxy resins. The degree of the reaction of phenylglycidylether (PGE) with anilides was higher than that with N-methylamides : this is due to the fact that the former proceeds mainly by the insertion of an epoxy group into the C-N linkage of an amide group. This insertion reaction took place most easily when imidazoles were used as a catalyst. In the reaction of aromatic polyamides (PA) with 2-function epoxy compounds (epoxy resins ; EP), the insertion reaction has also been recognized by examining IR-spectrum of a PA-EP reaction product. Tg and elastic modulus in the rubber region of the PA-EP reaction product were higher than those of PA. The phenomenon is considered to result from crosslinking of PA with EP by the insertion reaction.

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Thermo-oxidative degradation of epoxy resin cured with polyamideamine (Epikote 828 / Tohmide 225=50w / 50w) was studied using a simultaneous analytical system combining thermogravimetry (TG) -differential thermal analysis (DTA) -Fourier transform infrared spectroscopy (FTIR).
The resin used in this study was cured for 60 days at a room temperature, post-cured for 30 minutes at 100°C and finely ground to the size of 60 mesh pass. About 5 mg of a sample was loaded in a Pt-cell for TG-DAT analysis, and heated under the dry air at the flow rate of 100 cc/min.
The result was as follows : In the thermo-oxidative degradation process, the total gas profile obtained by FTIR was similar to the DTA- and DTG- time curves, and the evolved gases were mainly water vapor and carbon dioxide. In the first stage of thermo-oxidative degradation, there were a few organic acids, ammonia, and carbon monoxide, detected by FTIR. Thus, it was confirmed that the simultaneous TG-DTA-FTIR system was very useful for the analysis of the thermo-oxidative degradation process and gases evolved on heating the cured epoxy resin.

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