Modified carbon black (MCB) was obtained by oxidization and hydroxymethylation reactions with conductive carbon black (CB); in the MCB, some hydroxyl groups were introduced on the surface of the CB particles. CB, MCB, and a kind of organic ultraviolet absorber (UA) were used as UV antidotes, and binary composites and ternary composites were prepared by solvent casting with polystyrene, styrene-butadiene-styrene triblock copolymer, and poly(methyl methacrylate) as the matrix, respectively. In the binary composites, only one kind of UV antidote was used, whereas in the ternary composites, the organic and inorganic UAs were combined. The ultraviolet-visible absorption spectra of the composites were investigated extensively, and it was found that no synergism occurred when CB was combined with the organic absorber; on the other hand, an obvious synergism effect emerged when MCB was combined with the organic absorber in the same matrix, which was attributed to the formation of hydrogen bonds between MCB and UA. The interaction between MCB and UA was studied by Fourier transform infrared spectroscopy, differential scanning calorimetry, and transmission electron microscopy. (c) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 2566-2572, 2010