Thermal and electrical properties of polyimides containing tricyclic fused rings

Polyimides containing a series of tricyclic fused rings were synthesized by polymerization of the tricyclic diamines with aromatic tetracarboxylic acid dianhydrides. The thermal stability of a series of the polymers increased in the order of the thianthrene (SDP) containing polymers < the phenoxatiin (OSP) containing polymers < the dibenzo-p-dioxin (ODP) containing polymers. The polymers derived from 2,8-oriented tricyclic diamines showed somewhat lower glass transition temperature than those from 2,7-oriented diamines. The specific resistivity of the polymers decreased in the order of the SDP containing polymers > ODP containing polymers > OSP containing polymers. The kink temperatures in the temperature dependence curves of specific resistivity were in good agreement with the glass transition temperatures. The photoconductive properties of the polymers were measured using a surface type cell method.