Diaminomalenonitrile (DAMN), its N-alkyl derivatives and its Schiff base were studied as latent curing agents for epoxy resin.
The epoxy resin with such a curing agent in a dispersed state had a pot life longer than two months at room temperature and cured smoothly when heated above 150°C. The maximum glass-transition temperature (Tg) and cross-linking density (P _(E') ) for cured epoxy resins with DAMN and its N-alkyl derivatives were shown when the molar ratio of epoxy group to the curing agent was 6 : 1, contrary to expection from the chemical structures of these curing agents. The epoxy resins cured with Schiff base of DAMN had very high Tg, e. g. 200°C and P _(E') , though the maximum P _(E') and Tg for the cured resin was at the molar ratio of 5 : 1, and 4 : 1, respectively. In the results, DAMN and its derivatives were shown to be good latent curing agents, but the structure of the cured resins with these curing agents were not clarified.

View full abstract

Application of plastics for dry bearings and gears has been expanding rapidly in recent years.
This paper reviews our present understanding of the friction and wear mechaisms of polymeric materials, and tribological data on the wear of commercially available plastic-based bearing materials. In particular the effect of sliding speed, contact pressure and temperature on the friction and wear is discussed and the influence of their mechanical properties on the wear rate is also assessed. This article also reviews the data of the wear of commercially available plastic-based bearing materials to enable desginers to select appropriate ones.

View full abstract

Continuously for proving the theory on the activated state of ammonia catalyst, the present author investigated and discussed the articles on Mannich reactions. First in chapter 1 the fundamental articles by T. Shono and A. Takahashi (1926, 1953) and E. Imoto (1949) are introduced. Then the articles on Mannich reactions are abstracted : in chapter 2 Décombe (1933), Carlin and Landerl (1950), Moran et al (1952), Grillot and Gormley (1945), Tseou and Yang (1935) and in chapter 3 J. W. Burke and co-workers (1949, 1952) and lastly in chapter 4 Noda (1959), E. Imoto and Azuma (1958) etc. One of the important conclusions is that the activated radical NH₂·CH₂OH almost always enters the benzene ring in the position ortho to that of phenolic hydroxyl group.

View full abstract