Provided for resins by the present invention are flame-retarding, thermal stabilization and compatibilization methods, which make use of specific diguanamine derivatives, led by 2,5/2,6-bis(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]heptane and 1,3/1,4-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane, or derivatives thereof. The novel derivatives, polymeric microspheres and the like are also provided.