nanoresins AG (Charlottenburger, Germany) has developed a range of new toughening additives for cyanate esters, formulated particularly for cyanate esters that exhibit brittleness when used in aerospace applications. Albidur XP 1/669 is a low-viscosity core-shell elastomer concentrate in a cyanate ester resin, designed for use in composites applications. Reportedly, toughness and flexibility are increased without negatively affecting modulus, strength, T_g or processability.