Chemical AuxiliaryChina Pyromellitic Dianhydride/Pyromellitic Anhydride/ Benzene-1, 2, 4, 5-Tetracarboxylic Dianhydrid 89-32-7, Find details about China 98% Pmda, CAS No. 89-32-7 from Pyromellitic Dianhydride/Pyromellitic Anhydride/ Benzene-1, 2, 4, 5-Tetracarboxylic Dianhydrid 89-32-7