Abstract: There is disclosed an organic optical component prepared from a resin essentially comprising one or more repetitive structural units selected from the group consisting of structures represented by general formula (1); ##STR1## wherein A is either of the groups below. ##STR2## This invention provides an organic optical component with excellent transparency, heat resistance and mechanical strength as well as a low birefringence. This invention also provides a novel aromatic polyamide with a low permitivity and excellent transparency, processability and thermal stability, besides excellent heat resistance inherent in an aromatic polyamide.

Abstract: A low-birefringent organic optical component comprising a polymer prepared by polymerizing a racemic mixture of the monomer with an asymmetric spiro ring represented by general formula (1) as an essential ingredient; wherein ring A represents a monocyclic or polycyclic organic group, wherein two ring As are mutually bound each other via a spiro bond to form a spiro ring which has a molecular asymmetric structure; n is an integer of 0 to 10; X.sub.1 and Y.sub.1 are binding groups; and Z.sub.1 is a polymerization-active group. The component has excellent transparency, mechanical strength and heat resistance, as well as a low birefringence.

Abstract: A low birefringent organic optical component prepared from a resin consisting essentially of one or more repetitive structural units selected from the group consisting of structures represented by general formula (1); ##STR1## wherein A is either of the groups below. ##STR2## The organic optical component can exhibit excellent transparency, heat resistance and mechanical strength as well as a low birefringence. Also provided is a novel aromatic polyamide with a low permitivity and excellent transparency, processability and thermal stability, besides excellent heat resistance inherent in an aromatic polyamide.

Abstract: A is a polyimide based resin molding composition comprising 100 parts by weight of crystalline polyimide having recurring structural units of the formula (1): ##STR1## and 1.about.50 parts by weight of crystallization accelerators selected from bisimide compounds of specific structure, a mixture of bisimide compounds, and imide based oligomer. The composition remarkably accelerates the crystallization velocity of polyimide of the formula (1), crystallization can be completed within a greatly reduced cooling time after melt processing, and the crystallized polyimide resin has excellent properties.