Low‐temperature relaxation behavior was investigated for a bisphenol‐A and three spiroring type epoxide resins cured with aromatic and spiro‐ring‐type diamines. A new well‐defined relaxation denoted here as the β′ relaxation was observed from 50 to 100°C for the spiro‐ring‐type resin systems in both mechanical and dielectric measurements. The peak height and the activation energy of the β′ relaxation were entirely independent of the degree of curing. It is concluded that the β′ relaxation is due to the motion of p‐phenylene group adjacent to the spiro ring. The β′ relaxation was not observed in the bisphenol‐A‐type resin system.

No abstract

Dibasic acids containing a pyromellitimide ring were synthesized by the reaction of pyromelBy the condensation polymerization of the dibasic acids obtained above with diamines, polypyromellitimide-amides were synthesized. The polymers were soluble in m-cresol and sulfuric acid, and the inherent viscosities of the polymers ranged from 0.21 to 0.42 (in m-cresol). The polymers were found to be considerably heat-stable.

Several new types of polybenzimidazoquinazolines with a different recurring unit have been prepared by solution polycondensation in polyphosphoric acid followed by heating at elevated temperature under reduced pressure. The polymers thus obtained were light yellow to brown powdery materials hardly soluble in common organic solvents and soluble in concentrated sulfuric acid. The inherent viscosity of the polymers ranged from 0.1 to 0.58 and showed good thermal stability.

No abstract